Merge branch 'auth_md_processor' into server_creds_auth_md_processor

116 files changed, 3477 insertions, 1064 deletions

diff --git a/src/core/census/grpc_context.c b/src/core/census/grpc_context.c
index 0ed63469b6..11f1eb3d5d 100644
--- a/src/core/census/grpc_context.c
+++ b/src/core/census/grpc_context.c
@@ -32,14 +32,15 @@
  */
 
 #include <grpc/census.h>
-#include "src/core/census/grpc_context.h"
+#include <grpc/grpc.h>
+#include "src/core/surface/call.h"
 
 static void grpc_census_context_destroy(void *context) {
   census_context_destroy((census_context *)context);
 }
 
 void grpc_census_call_set_context(grpc_call *call, census_context *context) {
-  if (!census_available()) {
+  if (census_enabled() == CENSUS_FEATURE_NONE) {
     return;
   }
   if (context == NULL) {
diff --git a/src/core/census/initialize.c b/src/core/census/initialize.c
index 8016520641..8d60f790eb 100644
--- a/src/core/census/initialize.c
+++ b/src/core/census/initialize.c
@@ -33,20 +33,25 @@
 
 #include <grpc/census.h>
 
-static int census_fns_enabled = CENSUS_NONE;
+static int features_enabled = CENSUS_FEATURE_NONE;
 
-int census_initialize(int functions) {
-  if (census_fns_enabled != CENSUS_NONE) {
+int census_initialize(int features) {
+  if (features_enabled != CENSUS_FEATURE_NONE) {
     return 1;
   }
-  if (functions != CENSUS_NONE) {
+  if (features != CENSUS_FEATURE_NONE) {
     return 1;
   } else {
-    census_fns_enabled = functions;
+    features_enabled = features;
     return 0;
   }
 }
 
-void census_shutdown() { census_fns_enabled = CENSUS_NONE; }
+void census_shutdown(void) { features_enabled = CENSUS_FEATURE_NONE; }
 
-int census_available() { return (census_fns_enabled != CENSUS_NONE); }
+int census_supported(void) {
+  /* TODO(aveitch): improve this as we implement features... */
+  return CENSUS_FEATURE_NONE;
+}
+
+int census_enabled(void) { return features_enabled; }
diff --git a/src/core/census/grpc_context.h b/src/core/census/record_stat.c
index 4637e7218e..3dd918618b 100644
--- a/src/core/census/grpc_context.h
+++ b/src/core/census/record_stat.c
@@ -31,27 +31,8 @@
  *
  */
 
-/* GRPC <--> CENSUS context interface */
-
-#ifndef CENSUS_GRPC_CONTEXT_H
-#define CENSUS_GRPC_CONTEXT_H
-
 #include <grpc/census.h>
-#include "src/core/surface/call.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* Set census context for the call; Must be called before first call to
-   grpc_call_start_batch(). */
-void grpc_census_call_set_context(grpc_call *call, census_context *context);
-
-/* Retrieve the calls current census context. */
-census_context *grpc_census_call_get_context(grpc_call *call);
-
-#ifdef __cplusplus
-}
-#endif
+#include "src/core/census/rpc_stat_id.h"
 
-#endif /* CENSUS_GRPC_CONTEXT_H */
+void census_record_stat(census_context *context, census_stat *stats,
+                        size_t nstats) {}
diff --git a/src/core/census/rpc_stat_id.h b/src/core/census/rpc_stat_id.h
new file mode 100644
index 0000000000..fc0aa6f43f
--- /dev/null
+++ b/src/core/census/rpc_stat_id.h
@@ -0,0 +1,46 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef CENSUS_RPC_STAT_ID_H
+#define CENSUS_RPC_STAT_ID_H
+
+/* Stats ID's used for RPC measurements. */
+#define CENSUS_INVALID_STAT_ID 0     /* ID 0 is always invalid */
+#define CENSUS_RPC_CLIENT_REQUESTS 1 /* Count of client requests sent. */
+#define CENSUS_RPC_SERVER_REQUESTS 2 /* Count of server requests sent. */
+#define CENSUS_RPC_CLIENT_ERRORS 3   /* Client error counts. */
+#define CENSUS_RPC_SERVER_ERRORS 4   /* Server error counts. */
+#define CENSUS_RPC_CLIENT_LATENCY 5  /* Client side request latency. */
+#define CENSUS_RPC_SERVER_LATENCY 6  /* Server side request latency. */
+
+#endif /* CENSUS_RPC_STAT_ID_H */
diff --git a/src/core/channel/channel_args.c b/src/core/channel/channel_args.c
index 140f8bd656..c430b56fa2 100644
--- a/src/core/channel/channel_args.c
+++ b/src/core/channel/channel_args.c
@@ -114,7 +114,7 @@ void grpc_channel_args_destroy(grpc_channel_args *a) {
 }
 
 int grpc_channel_args_is_census_enabled(const grpc_channel_args *a) {
-  unsigned i;
+  size_t i;
   if (a == NULL) return 0;
   for (i = 0; i < a->num_args; i++) {
     if (0 == strcmp(a->args[i].key, GRPC_ARG_ENABLE_CENSUS)) {
@@ -124,26 +124,25 @@ int grpc_channel_args_is_census_enabled(const grpc_channel_args *a) {
   return 0;
 }
 
-grpc_compression_level grpc_channel_args_get_compression_level(
+grpc_compression_algorithm grpc_channel_args_get_compression_algorithm(
     const grpc_channel_args *a) {
   size_t i;
-  if (a) {
-    for (i = 0; a && i < a->num_args; ++i) {
-      if (a->args[i].type == GRPC_ARG_INTEGER &&
-          !strcmp(GRPC_COMPRESSION_LEVEL_ARG, a->args[i].key)) {
-        return a->args[i].value.integer;
-        break;
-      }
+  if (a == NULL) return 0;
+  for (i = 0; i < a->num_args; ++i) {
+    if (a->args[i].type == GRPC_ARG_INTEGER &&
+        !strcmp(GRPC_COMPRESSION_ALGORITHM_ARG, a->args[i].key)) {
+      return a->args[i].value.integer;
+      break;
     }
   }
-  return GRPC_COMPRESS_LEVEL_NONE;
+  return GRPC_COMPRESS_NONE;
 }
 
-void grpc_channel_args_set_compression_level(grpc_channel_args **a,
-                                             grpc_compression_level level) {
+grpc_channel_args *grpc_channel_args_set_compression_algorithm(
+    grpc_channel_args *a, grpc_compression_algorithm algorithm) {
   grpc_arg tmp;
   tmp.type = GRPC_ARG_INTEGER;
-  tmp.key = GRPC_COMPRESSION_LEVEL_ARG;
-  tmp.value.integer = level;
-  *a = grpc_channel_args_copy_and_add(*a, &tmp, 1);
+  tmp.key = GRPC_COMPRESSION_ALGORITHM_ARG;
+  tmp.value.integer = algorithm;
+  return grpc_channel_args_copy_and_add(a, &tmp, 1);
 }
diff --git a/src/core/channel/channel_args.h b/src/core/channel/channel_args.h
index 17849b7e59..7e6ddd3997 100644
--- a/src/core/channel/channel_args.h
+++ b/src/core/channel/channel_args.h
@@ -57,13 +57,14 @@ void grpc_channel_args_destroy(grpc_channel_args *a);
  * is specified in channel args, otherwise returns 0. */
 int grpc_channel_args_is_census_enabled(const grpc_channel_args *a);
 
-/** Returns the compression level set in \a a. */
-grpc_compression_level grpc_channel_args_get_compression_level(
+/** Returns the compression algorithm set in \a a. */
+grpc_compression_algorithm grpc_channel_args_get_compression_algorithm(
     const grpc_channel_args *a);
 
-/** Sets the compression level in \a a to \a level. Setting it to
- * GRPC_COMPRESS_LEVEL_NONE disables compression for the channel. */
-void grpc_channel_args_set_compression_level(grpc_channel_args **a,
-                                             grpc_compression_level level);
+/** Returns a channel arg instance with compression enabled. If \a a is
+ * non-NULL, its args are copied. N.B. GRPC_COMPRESS_NONE disables compression
+ * for the channel. */
+grpc_channel_args *grpc_channel_args_set_compression_algorithm(
+    grpc_channel_args *a, grpc_compression_algorithm algorithm);
 
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_ARGS_H */
diff --git a/src/core/channel/channel_stack.c b/src/core/channel/channel_stack.c
index e38dcb58b7..cd7c182ef2 100644
--- a/src/core/channel/channel_stack.c
+++ b/src/core/channel/channel_stack.c
@@ -191,6 +191,11 @@ void grpc_call_next_op(grpc_call_element *elem, grpc_transport_stream_op *op) {
   next_elem->filter->start_transport_stream_op(next_elem, op);
 }
 
+char *grpc_call_next_get_peer(grpc_call_element *elem) {
+  grpc_call_element *next_elem = elem + 1;
+  return next_elem->filter->get_peer(next_elem);
+}
+
 void grpc_channel_next_op(grpc_channel_element *elem, grpc_transport_op *op) {
   grpc_channel_element *next_elem = elem + 1;
   next_elem->filter->start_transport_op(next_elem, op);
diff --git a/src/core/channel/channel_stack.h b/src/core/channel/channel_stack.h
index 785be8925b..4a608b956e 100644
--- a/src/core/channel/channel_stack.h
+++ b/src/core/channel/channel_stack.h
@@ -104,6 +104,9 @@ typedef struct {
      The filter does not need to do any chaining */
   void (*destroy_channel_elem)(grpc_channel_element *elem);
 
+  /* Implement grpc_call_get_peer() */
+  char *(*get_peer)(grpc_call_element *elem);
+
   /* The name of this filter */
   const char *name;
 } grpc_channel_filter;
@@ -173,6 +176,8 @@ void grpc_call_next_op(grpc_call_element *elem, grpc_transport_stream_op *op);
 /* Call the next operation (depending on call directionality) in a channel
    stack */
 void grpc_channel_next_op(grpc_channel_element *elem, grpc_transport_op *op);
+/* Pass through a request to get_peer to the next child element */
+char *grpc_call_next_get_peer(grpc_call_element *elem);
 
 /* Given the top element of a channel stack, get the channel stack itself */
 grpc_channel_stack *grpc_channel_stack_from_top_element(
diff --git a/src/core/channel/client_channel.c b/src/core/channel/client_channel.c
index f890f99237..2cfca399b6 100644
--- a/src/core/channel/client_channel.c
+++ b/src/core/channel/client_channel.c
@@ -40,7 +40,6 @@
 #include "src/core/channel/connected_channel.h"
 #include "src/core/surface/channel.h"
 #include "src/core/iomgr/iomgr.h"
-#include "src/core/iomgr/pollset_set.h"
 #include "src/core/support/string.h"
 #include "src/core/transport/connectivity_state.h"
 #include <grpc/support/alloc.h>
@@ -77,8 +76,22 @@ typedef struct {
   grpc_iomgr_closure on_config_changed;
   /** connectivity state being tracked */
   grpc_connectivity_state_tracker state_tracker;
+  /** when an lb_policy arrives, should we try to exit idle */
+  int exit_idle_when_lb_policy_arrives;
+  /** pollset_set of interested parties in a new connection */
+  grpc_pollset_set pollset_set;
 } channel_data;
 
+/** We create one watcher for each new lb_policy that is returned from a resolver,
+    to watch for state changes from the lb_policy. When a state change is seen, we
+    update the channel, and create a new watcher */
+typedef struct {
+  channel_data *chand;
+  grpc_iomgr_closure on_changed;
+  grpc_connectivity_state state;
+  grpc_lb_policy *lb_policy;
+} lb_policy_connectivity_watcher;
+
 typedef enum {
   CALL_CREATED,
   CALL_WAITING_FOR_SEND,
@@ -132,7 +145,7 @@ static void handle_op_after_cancellation(grpc_call_element *elem,
     mdb.list.head = &calld->status;
     mdb.list.tail = &calld->details;
     mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future;
+    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
     grpc_sopb_add_metadata(op->recv_ops, mdb);
     *op->recv_state = GRPC_STREAM_CLOSED;
     op->on_done_recv->cb(op->on_done_recv->cb_arg, 1);
@@ -236,21 +249,6 @@ static void picked_target(void *arg, int iomgr_success) {
   }
 }
 
-static void pick_target(grpc_lb_policy *lb_policy, call_data *calld) {
-  grpc_metadata_batch *initial_metadata;
-  grpc_transport_stream_op *op = &calld->waiting_op;
-
-  GPR_ASSERT(op->bind_pollset);
-  GPR_ASSERT(op->send_ops);
-  GPR_ASSERT(op->send_ops->nops >= 1);
-  GPR_ASSERT(op->send_ops->ops[0].type == GRPC_OP_METADATA);
-  initial_metadata = &op->send_ops->ops[0].data.metadata;
-
-  grpc_iomgr_closure_init(&calld->async_setup_task, picked_target, calld);
-  grpc_lb_policy_pick(lb_policy, op->bind_pollset, initial_metadata,
-                      &calld->picked_channel, &calld->async_setup_task);
-}
-
 static grpc_iomgr_closure *merge_into_waiting_op(
     grpc_call_element *elem, grpc_transport_stream_op *new_op) {
   call_data *calld = elem->call_data;
@@ -280,6 +278,26 @@ static grpc_iomgr_closure *merge_into_waiting_op(
   return consumed_op;
 }
 
+static char *cc_get_peer(grpc_call_element *elem) {
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  grpc_subchannel_call *subchannel_call;
+  char *result;
+
+  gpr_mu_lock(&calld->mu_state);
+  if (calld->state == CALL_ACTIVE) {
+    subchannel_call = calld->subchannel_call;
+    GRPC_SUBCHANNEL_CALL_REF(subchannel_call, "get_peer");
+    gpr_mu_unlock(&calld->mu_state);
+    result = grpc_subchannel_call_get_peer(subchannel_call);
+    GRPC_SUBCHANNEL_CALL_UNREF(subchannel_call, "get_peer");
+    return result;
+  } else {
+    gpr_mu_unlock(&calld->mu_state);
+    return grpc_channel_get_target(chand->master);
+  }
+}
+
 static void perform_transport_stream_op(grpc_call_element *elem,
                                         grpc_transport_stream_op *op,
                                         int continuation) {
@@ -358,12 +376,23 @@ static void perform_transport_stream_op(grpc_call_element *elem,
           gpr_mu_lock(&chand->mu_config);
           lb_policy = chand->lb_policy;
           if (lb_policy) {
+            grpc_transport_stream_op *op = &calld->waiting_op;
+            grpc_pollset *bind_pollset = op->bind_pollset;
+            grpc_metadata_batch *initial_metadata = &op->send_ops->ops[0].data.metadata;
             GRPC_LB_POLICY_REF(lb_policy, "pick");
             gpr_mu_unlock(&chand->mu_config);
             calld->state = CALL_WAITING_FOR_PICK;
+
+            GPR_ASSERT(op->bind_pollset);
+            GPR_ASSERT(op->send_ops);
+            GPR_ASSERT(op->send_ops->nops >= 1);
+            GPR_ASSERT(
+                op->send_ops->ops[0].type == GRPC_OP_METADATA);
             gpr_mu_unlock(&calld->mu_state);
 
-            pick_target(lb_policy, calld);
+            grpc_iomgr_closure_init(&calld->async_setup_task, picked_target, calld);
+            grpc_lb_policy_pick(lb_policy, bind_pollset, initial_metadata,
+                                &calld->picked_channel, &calld->async_setup_task);
 
             GRPC_LB_POLICY_UNREF(lb_policy, "pick");
           } else if (chand->resolver != NULL) {
@@ -392,16 +421,53 @@ static void cc_start_transport_stream_op(grpc_call_element *elem,
   perform_transport_stream_op(elem, op, 0);
 }
 
+static void watch_lb_policy(channel_data *chand, grpc_lb_policy *lb_policy, grpc_connectivity_state current_state);
+
+static void on_lb_policy_state_changed(void *arg, int iomgr_success) {
+  lb_policy_connectivity_watcher *w = arg;
+
+  gpr_mu_lock(&w->chand->mu_config);
+  /* check if the notification is for a stale policy */
+  if (w->lb_policy == w->chand->lb_policy) {
+    grpc_connectivity_state_set(&w->chand->state_tracker, w->state,
+                                "lb_changed");
+    if (w->state != GRPC_CHANNEL_FATAL_FAILURE) {
+      watch_lb_policy(w->chand, w->lb_policy, w->state);
+    }
+  }
+  gpr_mu_unlock(&w->chand->mu_config);
+
+  GRPC_CHANNEL_INTERNAL_UNREF(w->chand->master, "watch_lb_policy");
+  gpr_free(w);
+}
+
+static void watch_lb_policy(channel_data *chand, grpc_lb_policy *lb_policy, grpc_connectivity_state current_state) {
+  lb_policy_connectivity_watcher *w = gpr_malloc(sizeof(*w));
+  GRPC_CHANNEL_INTERNAL_REF(chand->master, "watch_lb_policy");
+
+  w->chand = chand;
+  grpc_iomgr_closure_init(&w->on_changed, on_lb_policy_state_changed, w);
+  w->state = current_state;
+  w->lb_policy = lb_policy;
+  grpc_lb_policy_notify_on_state_change(lb_policy, &w->state, &w->on_changed);
+}
+
 static void cc_on_config_changed(void *arg, int iomgr_success) {
   channel_data *chand = arg;
   grpc_lb_policy *lb_policy = NULL;
   grpc_lb_policy *old_lb_policy;
   grpc_resolver *old_resolver;
   grpc_iomgr_closure *wakeup_closures = NULL;
+  grpc_connectivity_state state = GRPC_CHANNEL_TRANSIENT_FAILURE;
+  int exit_idle = 0;
 
   if (chand->incoming_configuration != NULL) {
     lb_policy = grpc_client_config_get_lb_policy(chand->incoming_configuration);
-    GRPC_LB_POLICY_REF(lb_policy, "channel");
+    if (lb_policy != NULL) {
+      GRPC_LB_POLICY_REF(lb_policy, "channel");
+      GRPC_LB_POLICY_REF(lb_policy, "config_change");
+      state = grpc_lb_policy_check_connectivity(lb_policy);
+    }
 
     grpc_client_config_unref(chand->incoming_configuration);
   }
@@ -415,13 +481,12 @@ static void cc_on_config_changed(void *arg, int iomgr_success) {
     wakeup_closures = chand->waiting_for_config_closures;
     chand->waiting_for_config_closures = NULL;
   }
-  gpr_mu_unlock(&chand->mu_config);
-
-  if (old_lb_policy) {
-    GRPC_LB_POLICY_UNREF(old_lb_policy, "channel");
+  if (lb_policy != NULL && chand->exit_idle_when_lb_policy_arrives) {
+    GRPC_LB_POLICY_REF(lb_policy, "exit_idle");
+    exit_idle = 1;
+    chand->exit_idle_when_lb_policy_arrives = 0;
   }
 
-  gpr_mu_lock(&chand->mu_config);
   if (iomgr_success && chand->resolver) {
     grpc_resolver *resolver = chand->resolver;
     GRPC_RESOLVER_REF(resolver, "channel-next");
@@ -430,11 +495,16 @@ static void cc_on_config_changed(void *arg, int iomgr_success) {
     grpc_resolver_next(resolver, &chand->incoming_configuration,
                        &chand->on_config_changed);
     GRPC_RESOLVER_UNREF(resolver, "channel-next");
+    grpc_connectivity_state_set(&chand->state_tracker, state,
+                                "new_lb+resolver");
+    if (lb_policy != NULL) {
+      watch_lb_policy(chand, lb_policy, state);
+    }
   } else {
     old_resolver = chand->resolver;
     chand->resolver = NULL;
     grpc_connectivity_state_set(&chand->state_tracker,
-                                GRPC_CHANNEL_FATAL_FAILURE);
+                                GRPC_CHANNEL_FATAL_FAILURE, "resolver_gone");
     gpr_mu_unlock(&chand->mu_config);
     if (old_resolver != NULL) {
       grpc_resolver_shutdown(old_resolver);
@@ -442,12 +512,24 @@ static void cc_on_config_changed(void *arg, int iomgr_success) {
     }
   }
 
+  if (exit_idle) {
+    grpc_lb_policy_exit_idle(lb_policy);
+    GRPC_LB_POLICY_UNREF(lb_policy, "exit_idle");
+  }
+
+  if (old_lb_policy != NULL) {
+    GRPC_LB_POLICY_UNREF(old_lb_policy, "channel");
+  }
+
   while (wakeup_closures) {
     grpc_iomgr_closure *next = wakeup_closures->next;
-    grpc_iomgr_add_callback(wakeup_closures);
+    wakeup_closures->cb(wakeup_closures->cb_arg, 1);
     wakeup_closures = next;
   }
 
+  if (lb_policy != NULL) {
+    GRPC_LB_POLICY_UNREF(lb_policy, "config_change");
+  }
   GRPC_CHANNEL_INTERNAL_UNREF(chand->master, "resolver");
 }
 
@@ -471,20 +553,22 @@ static void cc_start_transport_op(grpc_channel_element *elem,
     op->connectivity_state = NULL;
   }
 
+  if (!is_empty(op, sizeof(*op))) {
+    lb_policy = chand->lb_policy;
+    if (lb_policy) {
+      GRPC_LB_POLICY_REF(lb_policy, "broadcast");
+    }
+  }
+
   if (op->disconnect && chand->resolver != NULL) {
     grpc_connectivity_state_set(&chand->state_tracker,
-                                GRPC_CHANNEL_FATAL_FAILURE);
+                                GRPC_CHANNEL_FATAL_FAILURE, "disconnect");
     destroy_resolver = chand->resolver;
     chand->resolver = NULL;
     if (chand->lb_policy != NULL) {
       grpc_lb_policy_shutdown(chand->lb_policy);
-    }
-  }
-
-  if (!is_empty(op, sizeof(*op))) {
-    lb_policy = chand->lb_policy;
-    if (lb_policy) {
-      GRPC_LB_POLICY_REF(lb_policy, "broadcast");
+      GRPC_LB_POLICY_UNREF(chand->lb_policy, "channel");
+      chand->lb_policy = NULL;
     }
   }
   gpr_mu_unlock(&chand->mu_config);
@@ -518,7 +602,7 @@ static void init_call_elem(grpc_call_element *elem,
   gpr_mu_init(&calld->mu_state);
   calld->elem = elem;
   calld->state = CALL_CREATED;
-  calld->deadline = gpr_inf_future;
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 /* Destructor for call_data */
@@ -565,10 +649,11 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   gpr_mu_init(&chand->mu_config);
   chand->mdctx = metadata_context;
   chand->master = master;
+  grpc_pollset_set_init(&chand->pollset_set);
   grpc_iomgr_closure_init(&chand->on_config_changed, cc_on_config_changed,
                           chand);
 
-  grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE);
+  grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE, "client_channel");
 }
 
 /* Destructor for channel_data */
@@ -582,6 +667,8 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   if (chand->lb_policy != NULL) {
     GRPC_LB_POLICY_UNREF(chand->lb_policy, "channel");
   }
+  grpc_connectivity_state_destroy(&chand->state_tracker);
+  grpc_pollset_set_destroy(&chand->pollset_set);
   gpr_mu_destroy(&chand->mu_config);
 }
 
@@ -594,6 +681,7 @@ const grpc_channel_filter grpc_client_channel_filter = {
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    cc_get_peer,
     "client-channel",
 };
 
@@ -609,3 +697,47 @@ void grpc_client_channel_set_resolver(grpc_channel_stack *channel_stack,
   grpc_resolver_next(resolver, &chand->incoming_configuration,
                      &chand->on_config_changed);
 }
+
+grpc_connectivity_state grpc_client_channel_check_connectivity_state(
+    grpc_channel_element *elem, int try_to_connect) {
+  channel_data *chand = elem->channel_data;
+  grpc_connectivity_state out;
+  gpr_mu_lock(&chand->mu_config);
+  out = grpc_connectivity_state_check(&chand->state_tracker);
+  if (out == GRPC_CHANNEL_IDLE && try_to_connect) {
+    if (chand->lb_policy != NULL) {
+      grpc_lb_policy_exit_idle(chand->lb_policy);
+    } else {
+      chand->exit_idle_when_lb_policy_arrives = 1;
+    }
+  }
+  gpr_mu_unlock(&chand->mu_config);
+  return out;
+}
+
+void grpc_client_channel_watch_connectivity_state(
+    grpc_channel_element *elem, grpc_connectivity_state *state,
+    grpc_iomgr_closure *on_complete) {
+  channel_data *chand = elem->channel_data;
+  gpr_mu_lock(&chand->mu_config);
+  grpc_connectivity_state_notify_on_state_change(&chand->state_tracker, state,
+                                                 on_complete);
+  gpr_mu_unlock(&chand->mu_config);
+}
+
+grpc_pollset_set *grpc_client_channel_get_connecting_pollset_set(grpc_channel_element *elem) {
+  channel_data *chand = elem->channel_data;
+  return &chand->pollset_set;
+}
+
+void grpc_client_channel_add_interested_party(grpc_channel_element *elem,
+                                          grpc_pollset *pollset) {
+  channel_data *chand = elem->channel_data;
+  grpc_pollset_set_add_pollset(&chand->pollset_set, pollset);
+}
+
+void grpc_client_channel_del_interested_party(grpc_channel_element *elem,
+                                          grpc_pollset *pollset) {
+  channel_data *chand = elem->channel_data;
+  grpc_pollset_set_del_pollset(&chand->pollset_set, pollset);
+}
diff --git a/src/core/channel/client_channel.h b/src/core/channel/client_channel.h
index fd2be46145..cd81294eb3 100644
--- a/src/core/channel/client_channel.h
+++ b/src/core/channel/client_channel.h
@@ -52,4 +52,18 @@ extern const grpc_channel_filter grpc_client_channel_filter;
 void grpc_client_channel_set_resolver(grpc_channel_stack *channel_stack,
                                       grpc_resolver *resolver);
 
+grpc_connectivity_state grpc_client_channel_check_connectivity_state(
+    grpc_channel_element *elem, int try_to_connect);
+
+void grpc_client_channel_watch_connectivity_state(
+    grpc_channel_element *elem, grpc_connectivity_state *state,
+    grpc_iomgr_closure *on_complete);
+
+grpc_pollset_set *grpc_client_channel_get_connecting_pollset_set(grpc_channel_element *elem);
+
+void grpc_client_channel_add_interested_party(grpc_channel_element *channel,
+                                          grpc_pollset *pollset);
+void grpc_client_channel_del_interested_party(grpc_channel_element *channel,
+                                          grpc_pollset *pollset);
+
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CLIENT_CHANNEL_H */
diff --git a/src/core/channel/compress_filter.c b/src/core/channel/compress_filter.c
new file mode 100644
index 0000000000..8963c13b0f
--- /dev/null
+++ b/src/core/channel/compress_filter.c
@@ -0,0 +1,328 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include <grpc/compression.h>
+#include <grpc/support/log.h>
+#include <grpc/support/slice_buffer.h>
+
+#include "src/core/channel/compress_filter.h"
+#include "src/core/channel/channel_args.h"
+#include "src/core/compression/message_compress.h"
+
+typedef struct call_data {
+  gpr_slice_buffer slices; /**< Buffers up input slices to be compressed */
+  grpc_linked_mdelem compression_algorithm_storage;
+  int remaining_slice_bytes; /**< Input data to be read, as per BEGIN_MESSAGE */
+  int written_initial_metadata; /**< Already processed initial md? */
+  /** Compression algorithm we'll try to use. It may be given by incoming
+   * metadata, or by the channel's default compression settings. */
+  grpc_compression_algorithm compression_algorithm;
+   /** If true, contents of \a compression_algorithm are authoritative */
+  int has_compression_algorithm;
+} call_data;
+
+typedef struct channel_data {
+  /** Metadata key for the incoming (requested) compression algorithm */
+  grpc_mdstr *mdstr_request_compression_algorithm_key;
+  /** Metadata key for the outgoing (used) compression algorithm */
+  grpc_mdstr *mdstr_outgoing_compression_algorithm_key;
+  /** Precomputed metadata elements for all available compression algorithms */
+  grpc_mdelem *mdelem_compression_algorithms[GRPC_COMPRESS_ALGORITHMS_COUNT];
+  /** The default, channel-level, compression algorithm */
+  grpc_compression_algorithm default_compression_algorithm;
+} channel_data;
+
+/** Compress \a slices in place using \a algorithm. Returns 1 if compression did
+ * actually happen, 0 otherwise (for example if the compressed output size was
+ * larger than the raw input).
+ *
+ * Returns 1 if the data was actually compress and 0 otherwise. */
+static int compress_send_sb(grpc_compression_algorithm algorithm,
+                             gpr_slice_buffer *slices) {
+  int did_compress;
+  gpr_slice_buffer tmp;
+  gpr_slice_buffer_init(&tmp);
+  did_compress = grpc_msg_compress(algorithm, slices, &tmp);
+  if (did_compress) {
+    gpr_slice_buffer_swap(slices, &tmp);
+  }
+  gpr_slice_buffer_destroy(&tmp);
+  return did_compress;
+}
+
+/** For each \a md element from the incoming metadata, filter out the entry for
+ * "grpc-encoding", using its value to populate the call data's
+ * compression_algorithm field. */
+static grpc_mdelem* compression_md_filter(void *user_data, grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  channel_data *channeld = elem->channel_data;
+
+  if (md->key == channeld->mdstr_request_compression_algorithm_key) {
+    const char *md_c_str = grpc_mdstr_as_c_string(md->value);
+    if (!grpc_compression_algorithm_parse(md_c_str,
+                                          &calld->compression_algorithm)) {
+      gpr_log(GPR_ERROR, "Invalid compression algorithm: '%s'. Ignoring.",
+              md_c_str);
+      calld->compression_algorithm = GRPC_COMPRESS_NONE;
+    }
+    calld->has_compression_algorithm = 1;
+    return NULL;
+  }
+
+  return md;
+}
+
+static int skip_compression(channel_data *channeld, call_data *calld) {
+  if (calld->has_compression_algorithm) {
+     if (calld->compression_algorithm == GRPC_COMPRESS_NONE) {
+       return 1;
+     }
+     return 0;  /* we have an actual call-specific algorithm */
+  }
+  /* no per-call compression override */
+  return channeld->default_compression_algorithm == GRPC_COMPRESS_NONE;
+}
+
+/** Assembles a new grpc_stream_op_buffer with the compressed slices, modifying
+ * the associated GRPC_OP_BEGIN_MESSAGE accordingly (new compressed length,
+ * flags indicating compression is in effect) and replaces \a send_ops with it.
+ * */
+static void finish_compressed_sopb(grpc_stream_op_buffer *send_ops,
+                                   grpc_call_element *elem) {
+  size_t i;
+  call_data *calld = elem->call_data;
+  int new_slices_added = 0; /* GPR_FALSE */
+  grpc_metadata_batch metadata;
+  grpc_stream_op_buffer new_send_ops;
+  grpc_sopb_init(&new_send_ops);
+
+  for (i = 0; i < send_ops->nops; i++) {
+    grpc_stream_op *sop = &send_ops->ops[i];
+    switch (sop->type) {
+      case GRPC_OP_BEGIN_MESSAGE:
+        grpc_sopb_add_begin_message(
+            &new_send_ops, calld->slices.length,
+            sop->data.begin_message.flags | GRPC_WRITE_INTERNAL_COMPRESS);
+        break;
+      case GRPC_OP_SLICE:
+        /* Once we reach the slices section of the original buffer, simply add
+         * all the new (compressed) slices. We obviously want to do this only
+         * once, hence the "new_slices_added" guard. */
+        if (!new_slices_added) {
+          size_t j;
+          for (j = 0; j < calld->slices.count; ++j) {
+            grpc_sopb_add_slice(&new_send_ops,
+                                gpr_slice_ref(calld->slices.slices[j]));
+          }
+          new_slices_added = 1; /* GPR_TRUE */
+        }
+        break;
+      case GRPC_OP_METADATA:
+        /* move the metadata to the new buffer. */
+        grpc_metadata_batch_move(&metadata, &sop->data.metadata);
+        grpc_sopb_add_metadata(&new_send_ops, metadata);
+        break;
+      case GRPC_NO_OP:
+        break;
+    }
+  }
+  grpc_sopb_swap(send_ops, &new_send_ops);
+  grpc_sopb_destroy(&new_send_ops);
+}
+
+/** Filter's "main" function, called for any incoming grpc_transport_stream_op
+ * instance that holds a non-zero number of send operations, accesible to this
+ * function in \a send_ops.  */
+static void process_send_ops(grpc_call_element *elem,
+                             grpc_stream_op_buffer *send_ops) {
+  call_data *calld = elem->call_data;
+  channel_data *channeld = elem->channel_data;
+  size_t i;
+  int did_compress = 0;
+
+  /* In streaming calls, we need to reset the previously accumulated slices */
+  gpr_slice_buffer_reset_and_unref(&calld->slices);
+  for (i = 0; i < send_ops->nops; ++i) {
+    grpc_stream_op *sop = &send_ops->ops[i];
+    switch (sop->type) {
+      case GRPC_OP_BEGIN_MESSAGE:
+        /* buffer up slices until we've processed all the expected ones (as
+         * given by GRPC_OP_BEGIN_MESSAGE) */
+        calld->remaining_slice_bytes = sop->data.begin_message.length;
+        if (sop->data.begin_message.flags & GRPC_WRITE_NO_COMPRESS) {
+          calld->has_compression_algorithm = 1;  /* GPR_TRUE */
+          calld->compression_algorithm = GRPC_COMPRESS_NONE;
+        }
+        break;
+      case GRPC_OP_METADATA:
+        if (!calld->written_initial_metadata) {
+          /* Parse incoming request for compression. If any, it'll be available
+           * at calld->compression_algorithm */
+          grpc_metadata_batch_filter(&(sop->data.metadata),
+                                     compression_md_filter, elem);
+          if (!calld->has_compression_algorithm) {
+            /* If no algorithm was found in the metadata and we aren't
+             * exceptionally skipping compression, fall back to the channel
+             * default */
+            calld->compression_algorithm =
+                channeld->default_compression_algorithm;
+            calld->has_compression_algorithm = 1; /* GPR_TRUE */
+          }
+          grpc_metadata_batch_add_tail(
+              &(sop->data.metadata), &calld->compression_algorithm_storage,
+              GRPC_MDELEM_REF(channeld->mdelem_compression_algorithms
+                                  [calld->compression_algorithm]));
+          calld->written_initial_metadata = 1; /* GPR_TRUE */
+        }
+        break;
+      case GRPC_OP_SLICE:
+        if (skip_compression(channeld, calld)) continue;
+        GPR_ASSERT(calld->remaining_slice_bytes > 0);
+        /* Increase input ref count, gpr_slice_buffer_add takes ownership.  */
+        gpr_slice_buffer_add(&calld->slices, gpr_slice_ref(sop->data.slice));
+        calld->remaining_slice_bytes -= GPR_SLICE_LENGTH(sop->data.slice);
+        if (calld->remaining_slice_bytes == 0) {
+          did_compress =
+              compress_send_sb(calld->compression_algorithm, &calld->slices);
+        }
+        break;
+      case GRPC_NO_OP:
+        break;
+    }
+  }
+
+  /* Modify the send_ops stream_op_buffer depending on whether compression was
+   * carried out */
+  if (did_compress) {
+    finish_compressed_sopb(send_ops, elem);
+  }
+}
+
+/* Called either:
+     - in response to an API call (or similar) from above, to send something
+     - a network event (or similar) from below, to receive something
+   op contains type and call direction information, in addition to the data
+   that is being sent or received. */
+static void compress_start_transport_stream_op(grpc_call_element *elem,
+                                               grpc_transport_stream_op *op) {
+  if (op->send_ops && op->send_ops->nops > 0) {
+    process_send_ops(elem, op->send_ops);
+  }
+
+  /* pass control down the stack */
+  grpc_call_next_op(elem, op);
+}
+
+/* Constructor for call_data */
+static void init_call_elem(grpc_call_element *elem,
+                           const void *server_transport_data,
+                           grpc_transport_stream_op *initial_op) {
+  /* grab pointers to our data from the call element */
+  call_data *calld = elem->call_data;
+
+  /* initialize members */
+  gpr_slice_buffer_init(&calld->slices);
+  calld->has_compression_algorithm = 0;
+  calld->written_initial_metadata = 0; /* GPR_FALSE */
+
+  if (initial_op) {
+    if (initial_op->send_ops && initial_op->send_ops->nops > 0) {
+      process_send_ops(elem, initial_op->send_ops);
+    }
+  }
+}
+
+/* Destructor for call_data */
+static void destroy_call_elem(grpc_call_element *elem) {
+  /* grab pointers to our data from the call element */
+  call_data *calld = elem->call_data;
+  gpr_slice_buffer_destroy(&calld->slices);
+}
+
+/* Constructor for channel_data */
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
+                              const grpc_channel_args *args, grpc_mdctx *mdctx,
+                              int is_first, int is_last) {
+  channel_data *channeld = elem->channel_data;
+  grpc_compression_algorithm algo_idx;
+
+  channeld->default_compression_algorithm =
+      grpc_channel_args_get_compression_algorithm(args);
+
+  channeld->mdstr_request_compression_algorithm_key =
+      grpc_mdstr_from_string(mdctx, GRPC_COMPRESS_REQUEST_ALGORITHM_KEY, 0);
+
+  channeld->mdstr_outgoing_compression_algorithm_key =
+      grpc_mdstr_from_string(mdctx, "grpc-encoding", 0);
+
+  for (algo_idx = 0; algo_idx < GRPC_COMPRESS_ALGORITHMS_COUNT; ++algo_idx) {
+    char *algorithm_name;
+    GPR_ASSERT(grpc_compression_algorithm_name(algo_idx, &algorithm_name) != 0);
+    channeld->mdelem_compression_algorithms[algo_idx] =
+        grpc_mdelem_from_metadata_strings(
+            mdctx,
+            GRPC_MDSTR_REF(channeld->mdstr_outgoing_compression_algorithm_key),
+            grpc_mdstr_from_string(mdctx, algorithm_name, 0));
+  }
+
+  GPR_ASSERT(!is_last);
+}
+
+/* Destructor for channel data */
+static void destroy_channel_elem(grpc_channel_element *elem) {
+  channel_data *channeld = elem->channel_data;
+  grpc_compression_algorithm algo_idx;
+
+  GRPC_MDSTR_UNREF(channeld->mdstr_request_compression_algorithm_key);
+  GRPC_MDSTR_UNREF(channeld->mdstr_outgoing_compression_algorithm_key);
+  for (algo_idx = 0; algo_idx < GRPC_COMPRESS_ALGORITHMS_COUNT;
+       ++algo_idx) {
+    GRPC_MDELEM_UNREF(channeld->mdelem_compression_algorithms[algo_idx]);
+  }
+}
+
+const grpc_channel_filter grpc_compress_filter = {
+    compress_start_transport_stream_op,
+    grpc_channel_next_op,
+    sizeof(call_data),
+    init_call_elem,
+    destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    grpc_call_next_get_peer,
+    "compress"};
diff --git a/src/core/channel/compress_filter.h b/src/core/channel/compress_filter.h
new file mode 100644
index 0000000000..0694e2c1dd
--- /dev/null
+++ b/src/core/channel/compress_filter.h
@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CHANNEL_COMPRESS_FILTER_H
+#define GRPC_INTERNAL_CORE_CHANNEL_COMPRESS_FILTER_H
+
+#include "src/core/channel/channel_stack.h"
+
+#define GRPC_COMPRESS_REQUEST_ALGORITHM_KEY "internal:grpc-encoding-request"
+
+/** Compression filter for outgoing data.
+ *
+ * See <grpc/compression.h> for the available compression settings.
+ *
+ * Compression settings may come from:
+ *  - Channel configuration, as established at channel creation time.
+ *  - The metadata accompanying the outgoing data to be compressed. This is
+ *    taken as a request only. We may choose not to honor it. The metadata key
+ *    is given by \a GRPC_COMPRESS_REQUEST_ALGORITHM_KEY.
+ *
+ * Compression can be disabled for concrete messages (for instance in order to
+ * prevent CRIME/BEAST type attacks) by having the GRPC_WRITE_NO_COMPRESS set in
+ * the BEGIN_MESSAGE flags.
+ *
+ * The attempted compression mechanism is added to the resulting initial
+ * metadata under the'grpc-encoding' key.
+ *
+ * If compression is actually performed, BEGIN_MESSAGE's flag is modified to
+ * incorporate GRPC_WRITE_INTERNAL_COMPRESS. Otherwise, and regardless of the
+ * aforementioned 'grpc-encoding' metadata value, data will pass through
+ * uncompressed. */
+
+extern const grpc_channel_filter grpc_compress_filter;
+
+#endif  /* GRPC_INTERNAL_CORE_CHANNEL_COMPRESS_FILTER_H */
diff --git a/src/core/channel/connected_channel.c b/src/core/channel/connected_channel.c
index 34d07de519..b95ed06f2b 100644
--- a/src/core/channel/connected_channel.c
+++ b/src/core/channel/connected_channel.c
@@ -119,6 +119,11 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   grpc_transport_destroy(cd->transport);
 }
 
+static char *con_get_peer(grpc_call_element *elem) {
+  channel_data *chand = elem->channel_data;
+  return grpc_transport_get_peer(chand->transport);
+}
+
 const grpc_channel_filter grpc_connected_channel_filter = {
     con_start_transport_stream_op,
     con_start_transport_op,
@@ -128,6 +133,7 @@ const grpc_channel_filter grpc_connected_channel_filter = {
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    con_get_peer,
     "connected",
 };
 
diff --git a/src/core/channel/http_client_filter.c b/src/core/channel/http_client_filter.c
index 63e4912397..48c623d359 100644
--- a/src/core/channel/http_client_filter.c
+++ b/src/core/channel/http_client_filter.c
@@ -32,14 +32,20 @@
 
 #include "src/core/channel/http_client_filter.h"
 #include <string.h>
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include "src/core/support/string.h"
 
 typedef struct call_data {
   grpc_linked_mdelem method;
   grpc_linked_mdelem scheme;
+  grpc_linked_mdelem authority;
   grpc_linked_mdelem te_trailers;
   grpc_linked_mdelem content_type;
+  grpc_linked_mdelem user_agent;
   int sent_initial_metadata;
+  int sent_authority;
 
   int got_initial_metadata;
   grpc_stream_op_buffer *recv_ops;
@@ -58,6 +64,9 @@ typedef struct channel_data {
   grpc_mdelem *scheme;
   grpc_mdelem *content_type;
   grpc_mdelem *status;
+  grpc_mdelem *default_authority;
+  /** complete user agent mdelem */
+  grpc_mdelem *user_agent;
 } channel_data;
 
 /* used to silence 'variable not used' warnings */
@@ -92,6 +101,23 @@ static void hc_on_recv(void *user_data, int success) {
   calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
 }
 
+static grpc_mdelem *client_strip_filter(void *user_data, grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  channel_data *channeld = elem->channel_data;
+  /* eat the things we'd like to set ourselves */
+  if (md->key == channeld->method->key) return NULL;
+  if (md->key == channeld->scheme->key) return NULL;
+  if (md->key == channeld->te_trailers->key) return NULL;
+  if (md->key == channeld->content_type->key) return NULL;
+  if (md->key == channeld->user_agent->key) return NULL;
+  if (channeld->default_authority &&
+      channeld->default_authority->key == md->key) {
+    calld->sent_authority = 1;
+  }
+  return md;
+}
+
 static void hc_mutate_op(grpc_call_element *elem,
                          grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
@@ -105,16 +131,24 @@ static void hc_mutate_op(grpc_call_element *elem,
       grpc_stream_op *op = &ops[i];
       if (op->type != GRPC_OP_METADATA) continue;
       calld->sent_initial_metadata = 1;
+      grpc_metadata_batch_filter(&op->data.metadata, client_strip_filter, elem);
       /* Send : prefixed headers, which have to be before any application
          layer headers. */
       grpc_metadata_batch_add_head(&op->data.metadata, &calld->method,
                                    GRPC_MDELEM_REF(channeld->method));
       grpc_metadata_batch_add_head(&op->data.metadata, &calld->scheme,
                                    GRPC_MDELEM_REF(channeld->scheme));
+      if (channeld->default_authority && !calld->sent_authority) {
+        grpc_metadata_batch_add_head(
+            &op->data.metadata, &calld->authority,
+            GRPC_MDELEM_REF(channeld->default_authority));
+      }
       grpc_metadata_batch_add_tail(&op->data.metadata, &calld->te_trailers,
                                    GRPC_MDELEM_REF(channeld->te_trailers));
       grpc_metadata_batch_add_tail(&op->data.metadata, &calld->content_type,
                                    GRPC_MDELEM_REF(channeld->content_type));
+      grpc_metadata_batch_add_tail(&op->data.metadata, &calld->user_agent,
+                                   GRPC_MDELEM_REF(channeld->user_agent));
       break;
     }
   }
@@ -141,6 +175,7 @@ static void init_call_elem(grpc_call_element *elem,
   call_data *calld = elem->call_data;
   calld->sent_initial_metadata = 0;
   calld->got_initial_metadata = 0;
+  calld->sent_authority = 0;
   calld->on_done_recv = NULL;
   grpc_iomgr_closure_init(&calld->hc_on_recv, hc_on_recv, elem);
   if (initial_op) hc_mutate_op(elem, initial_op);
@@ -169,10 +204,61 @@ static const char *scheme_from_args(const grpc_channel_args *args) {
   return "http";
 }
 
+static grpc_mdstr *user_agent_from_args(grpc_mdctx *mdctx,
+                                        const grpc_channel_args *args) {
+  gpr_strvec v;
+  size_t i;
+  int is_first = 1;
+  char *tmp;
+  grpc_mdstr *result;
+
+  gpr_strvec_init(&v);
+
+  for (i = 0; args && i < args->num_args; i++) {
+    if (0 == strcmp(args->args[i].key, GRPC_ARG_PRIMARY_USER_AGENT_STRING)) {
+      if (args->args[i].type != GRPC_ARG_STRING) {
+        gpr_log(GPR_ERROR, "Channel argument '%s' should be a string",
+                GRPC_ARG_PRIMARY_USER_AGENT_STRING);
+      } else {
+        if (!is_first) gpr_strvec_add(&v, gpr_strdup(" "));
+        is_first = 0;
+        gpr_strvec_add(&v, gpr_strdup(args->args[i].value.string));
+      }
+    }
+  }
+
+  gpr_asprintf(&tmp, "%sgrpc-c/%s (%s)", is_first ? "" : " ",
+               grpc_version_string(), GPR_PLATFORM_STRING);
+  is_first = 0;
+  gpr_strvec_add(&v, tmp);
+
+  for (i = 0; args && i < args->num_args; i++) {
+    if (0 == strcmp(args->args[i].key, GRPC_ARG_SECONDARY_USER_AGENT_STRING)) {
+      if (args->args[i].type != GRPC_ARG_STRING) {
+        gpr_log(GPR_ERROR, "Channel argument '%s' should be a string",
+                GRPC_ARG_SECONDARY_USER_AGENT_STRING);
+      } else {
+        if (!is_first) gpr_strvec_add(&v, gpr_strdup(" "));
+        is_first = 0;
+        gpr_strvec_add(&v, gpr_strdup(args->args[i].value.string));
+      }
+    }
+  }
+
+  tmp = gpr_strvec_flatten(&v, NULL);
+  gpr_strvec_destroy(&v);
+  result = grpc_mdstr_from_string(mdctx, tmp, 0);
+  gpr_free(tmp);
+
+  return result;
+}
+
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
+                              const grpc_channel_args *channel_args,
+                              grpc_mdctx *mdctx, int is_first, int is_last) {
+  size_t i;
+
   /* grab pointers to our data from the channel element */
   channel_data *channeld = elem->channel_data;
 
@@ -181,14 +267,32 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
      path */
   GPR_ASSERT(!is_last);
 
+  channeld->default_authority = NULL;
+  if (channel_args) {
+    for (i = 0; i < channel_args->num_args; i++) {
+      if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
+        if (channel_args->args[i].type != GRPC_ARG_STRING) {
+          gpr_log(GPR_ERROR, "%s: must be an string",
+                  GRPC_ARG_DEFAULT_AUTHORITY);
+        } else {
+          channeld->default_authority = grpc_mdelem_from_strings(
+              mdctx, ":authority", channel_args->args[i].value.string);
+        }
+      }
+    }
+  }
+
   /* initialize members */
   channeld->te_trailers = grpc_mdelem_from_strings(mdctx, "te", "trailers");
   channeld->method = grpc_mdelem_from_strings(mdctx, ":method", "POST");
-  channeld->scheme =
-      grpc_mdelem_from_strings(mdctx, ":scheme", scheme_from_args(args));
+  channeld->scheme = grpc_mdelem_from_strings(mdctx, ":scheme",
+                                              scheme_from_args(channel_args));
   channeld->content_type =
       grpc_mdelem_from_strings(mdctx, "content-type", "application/grpc");
   channeld->status = grpc_mdelem_from_strings(mdctx, ":status", "200");
+  channeld->user_agent = grpc_mdelem_from_metadata_strings(
+      mdctx, grpc_mdstr_from_string(mdctx, "user-agent", 0),
+      user_agent_from_args(mdctx, channel_args));
 }
 
 /* Destructor for channel data */
@@ -201,9 +305,14 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   GRPC_MDELEM_UNREF(channeld->scheme);
   GRPC_MDELEM_UNREF(channeld->content_type);
   GRPC_MDELEM_UNREF(channeld->status);
+  GRPC_MDELEM_UNREF(channeld->user_agent);
+  if (channeld->default_authority) {
+    GRPC_MDELEM_UNREF(channeld->default_authority);
+  }
 }
 
 const grpc_channel_filter grpc_http_client_filter = {
     hc_start_transport_op, grpc_channel_next_op, sizeof(call_data),
     init_call_elem,        destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,     destroy_channel_elem, "http-client"};
+    init_channel_elem,     destroy_channel_elem, grpc_call_next_get_peer,
+    "http-client"};
diff --git a/src/core/channel/http_server_filter.c b/src/core/channel/http_server_filter.c
index a6cbb5a7f4..0955ae319a 100644
--- a/src/core/channel/http_server_filter.c
+++ b/src/core/channel/http_server_filter.c
@@ -44,6 +44,7 @@ typedef struct call_data {
   gpr_uint8 sent_status;
   gpr_uint8 seen_scheme;
   gpr_uint8 seen_te_trailers;
+  gpr_uint8 seen_authority;
   grpc_linked_mdelem status;
 
   grpc_stream_op_buffer *recv_ops;
@@ -125,6 +126,9 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
     }
     calld->seen_path = 1;
     return md;
+  } else if (md->key == channeld->authority_key) {
+    calld->seen_authority = 1;
+    return md;
   } else if (md->key == channeld->host_key) {
     /* translate host to :authority since :authority may be
        omitted */
@@ -132,6 +136,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
         channeld->mdctx, GRPC_MDSTR_REF(channeld->authority_key),
         GRPC_MDSTR_REF(md->value));
     GRPC_MDELEM_UNREF(md);
+    calld->seen_authority = 1;
     return authority;
   } else {
     return md;
@@ -154,12 +159,15 @@ static void hs_on_recv(void *user_data, int success) {
          (:method, :scheme, content-type, with :path and :authority covered
          at the channel level right now) */
       if (calld->seen_post && calld->seen_scheme && calld->seen_te_trailers &&
-          calld->seen_path) {
+          calld->seen_path && calld->seen_authority) {
         /* do nothing */
       } else {
         if (!calld->seen_path) {
           gpr_log(GPR_ERROR, "Missing :path header");
         }
+        if (!calld->seen_authority) {
+          gpr_log(GPR_ERROR, "Missing :authority header");
+        }
         if (!calld->seen_post) {
           gpr_log(GPR_ERROR, "Missing :method header");
         }
@@ -250,9 +258,9 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   channeld->http_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "http");
   channeld->https_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "https");
   channeld->grpc_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "grpc");
-  channeld->path_key = grpc_mdstr_from_string(mdctx, ":path");
-  channeld->authority_key = grpc_mdstr_from_string(mdctx, ":authority");
-  channeld->host_key = grpc_mdstr_from_string(mdctx, "host");
+  channeld->path_key = grpc_mdstr_from_string(mdctx, ":path", 0);
+  channeld->authority_key = grpc_mdstr_from_string(mdctx, ":authority", 0);
+  channeld->host_key = grpc_mdstr_from_string(mdctx, "host", 0);
   channeld->content_type =
       grpc_mdelem_from_strings(mdctx, "content-type", "application/grpc");
 
@@ -280,4 +288,5 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 const grpc_channel_filter grpc_http_server_filter = {
     hs_start_transport_op, grpc_channel_next_op, sizeof(call_data),
     init_call_elem,        destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,     destroy_channel_elem, "http-server"};
+    init_channel_elem,     destroy_channel_elem, grpc_call_next_get_peer,
+    "http-server"};
diff --git a/src/core/channel/noop_filter.c b/src/core/channel/noop_filter.c
index 5117723617..d631885aaf 100644
--- a/src/core/channel/noop_filter.c
+++ b/src/core/channel/noop_filter.c
@@ -127,4 +127,5 @@ const grpc_channel_filter grpc_no_op_filter = {noop_start_transport_stream_op,
                                                sizeof(channel_data),
                                                init_channel_elem,
                                                destroy_channel_elem,
+                                               grpc_call_next_get_peer,
                                                "no-op"};
diff --git a/src/core/client_config/README.md b/src/core/client_config/README.md
index d7aed27223..fff7a5af5b 100644
--- a/src/core/client_config/README.md
+++ b/src/core/client_config/README.md
@@ -1,7 +1,7 @@
 Client Configuration Support for GRPC
 =====================================
 
-This library provides high level configuration machinery to construct client 
+This library provides high level configuration machinery to construct client
 channels and load balance between them.
 
 Each grpc_channel is created with a grpc_resolver. It is the resolver's duty
@@ -22,32 +22,33 @@ Load Balancing
 --------------
 
 Load balancing configuration is provided by a grpc_lb_policy object, stored as
-part of grpc_client_config. 
+part of grpc_client_config.
 
-A load balancing policies primary job is to pick a target server given only the
-initial metadata for a request. It does this by providing a grpc_subchannel 
+The primary job of the load balancing policies is to pick a target server given only the
+initial metadata for a request. It does this by providing a grpc_subchannel
 object to the owning channel.
 
 
 Sub-Channels
 ------------
 
-A sub-channel provides a connection to a server for a client channel. It has a 
-connectivity state like a regular channel, and so can be connected or 
-disconnected. This connectivity state can be used to inform load balancing 
+A sub-channel provides a connection to a server for a client channel. It has a
+connectivity state like a regular channel, and so can be connected or
+disconnected. This connectivity state can be used to inform load balancing
 decisions (for example, by avoiding disconnected backends).
 
 Configured sub-channels are fully setup to participate in the grpc data plane.
 Their behavior is specified by a set of grpc channel filters defined at their
-construction. To customize this behavior, resolvers build grpc_subchannel_factory 
-objects, which use the decorator pattern to customize construction arguments for 
-concrete grpc_subchannel instances.
+construction. To customize this behavior, resolvers build
+grpc_subchannel_factory objects, which use the decorator pattern to customize
+construction arguments for concrete grpc_subchannel instances.
 
 
 Naming for GRPC
 ===============
 
-Names in GRPC are represented by a URI.
+Names in GRPC are represented by a URI (as defined in
+[RFC 3986](https://tools.ietf.org/html/rfc3986)).
 
 The following schemes are currently supported:
 
@@ -55,6 +56,11 @@ dns:///host:port - dns schemes are currently supported so long as authority is
                    empty (authority based dns resolution is expected in a future
                    release)
 
-unix:path        - the unix scheme is used to create and connect to unix domain 
-                   sockets - the authority must be empty, and the path represents
-                   the absolute or relative path to the desired socket
+unix:path        - the unix scheme is used to create and connect to unix domain
+                   sockets - the authority must be empty, and the path
+                   represents the absolute or relative path to the desired
+                   socket
+
+ipv4:host:port   - a pre-resolved ipv4 dotted decimal address/port combination
+
+ipv6:[host]:port - a pre-resolved ipv6 address/port combination
diff --git a/src/core/client_config/lb_policies/pick_first.c b/src/core/client_config/lb_policies/pick_first.c
index 73da624aff..5ae2e0ea52 100644
--- a/src/core/client_config/lb_policies/pick_first.c
+++ b/src/core/client_config/lb_policies/pick_first.c
@@ -62,6 +62,8 @@ typedef struct {
   grpc_subchannel *selected;
   /** have we started picking? */
   int started_picking;
+  /** are we shut down? */
+  int shutdown;
   /** which subchannel are we watching? */
   size_t checking_subchannel;
   /** what is the connectivity of that channel? */
@@ -73,12 +75,30 @@ typedef struct {
   grpc_connectivity_state_tracker state_tracker;
 } pick_first_lb_policy;
 
+static void del_interested_parties_locked(pick_first_lb_policy *p) {
+  pending_pick *pp;
+  for (pp = p->pending_picks; pp; pp = pp->next) {
+    grpc_subchannel_del_interested_party(p->subchannels[p->checking_subchannel],
+                                         pp->pollset);
+  }
+}
+
+static void add_interested_parties_locked(pick_first_lb_policy *p) {
+  pending_pick *pp;
+  for (pp = p->pending_picks; pp; pp = pp->next) {
+    grpc_subchannel_add_interested_party(p->subchannels[p->checking_subchannel],
+                                         pp->pollset);
+  }
+}
+
 void pf_destroy(grpc_lb_policy *pol) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   size_t i;
+  del_interested_parties_locked(p);
   for (i = 0; i < p->num_subchannels; i++) {
     GRPC_SUBCHANNEL_UNREF(p->subchannels[i], "pick_first");
   }
+  grpc_connectivity_state_destroy(&p->state_tracker);
   gpr_free(p->subchannels);
   gpr_mu_destroy(&p->mu);
   gpr_free(p);
@@ -88,12 +108,35 @@ void pf_shutdown(grpc_lb_policy *pol) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
   gpr_mu_lock(&p->mu);
+  del_interested_parties_locked(p);
+  p->shutdown = 1;
   while ((pp = p->pending_picks)) {
     p->pending_picks = pp->next;
     *pp->target = NULL;
     grpc_iomgr_add_delayed_callback(pp->on_complete, 0);
     gpr_free(pp);
   }
+  grpc_connectivity_state_set(&p->state_tracker, GRPC_CHANNEL_FATAL_FAILURE,
+                              "shutdown");
+  gpr_mu_unlock(&p->mu);
+}
+
+static void start_picking(pick_first_lb_policy *p) {
+  p->started_picking = 1;
+  p->checking_subchannel = 0;
+  p->checking_connectivity = GRPC_CHANNEL_IDLE;
+  GRPC_LB_POLICY_REF(&p->base, "pick_first_connectivity");
+  grpc_subchannel_notify_on_state_change(p->subchannels[p->checking_subchannel],
+                                         &p->checking_connectivity,
+                                         &p->connectivity_changed);
+}
+
+void pf_exit_idle(grpc_lb_policy *pol) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  gpr_mu_lock(&p->mu);
+  if (!p->started_picking) {
+    start_picking(p);
+  }
   gpr_mu_unlock(&p->mu);
 }
 
@@ -109,13 +152,7 @@ void pf_pick(grpc_lb_policy *pol, grpc_pollset *pollset,
     on_complete->cb(on_complete->cb_arg, 1);
   } else {
     if (!p->started_picking) {
-      p->started_picking = 1;
-      p->checking_subchannel = 0;
-      p->checking_connectivity = GRPC_CHANNEL_IDLE;
-      GRPC_LB_POLICY_REF(pol, "pick_first_connectivity");
-      grpc_subchannel_notify_on_state_change(
-          p->subchannels[p->checking_subchannel], &p->checking_connectivity,
-          &p->connectivity_changed);
+      start_picking(p);
     }
     grpc_subchannel_add_interested_party(p->subchannels[p->checking_subchannel],
                                          pollset);
@@ -129,77 +166,97 @@ void pf_pick(grpc_lb_policy *pol, grpc_pollset *pollset,
   }
 }
 
-static void del_interested_parties_locked(pick_first_lb_policy *p) {
-  pending_pick *pp;
-  for (pp = p->pending_picks; pp; pp = pp->next) {
-    grpc_subchannel_del_interested_party(p->subchannels[p->checking_subchannel],
-                                         pp->pollset);
-  }
-}
-
-static void add_interested_parties_locked(pick_first_lb_policy *p) {
-  pending_pick *pp;
-  for (pp = p->pending_picks; pp; pp = pp->next) {
-    grpc_subchannel_add_interested_party(p->subchannels[p->checking_subchannel],
-                                         pp->pollset);
-  }
-}
-
 static void pf_connectivity_changed(void *arg, int iomgr_success) {
   pick_first_lb_policy *p = arg;
   pending_pick *pp;
   int unref = 0;
 
   gpr_mu_lock(&p->mu);
-loop:
-  switch (p->checking_connectivity) {
-    case GRPC_CHANNEL_READY:
-      p->selected = p->subchannels[p->checking_subchannel];
-      while ((pp = p->pending_picks)) {
-        p->pending_picks = pp->next;
-        *pp->target = p->selected;
-        grpc_subchannel_del_interested_party(p->selected, pp->pollset);
-        grpc_iomgr_add_delayed_callback(pp->on_complete, 1);
-        gpr_free(pp);
-      }
-      unref = 1;
-      break;
-    case GRPC_CHANNEL_TRANSIENT_FAILURE:
-      del_interested_parties_locked(p);
-      p->checking_subchannel =
-          (p->checking_subchannel + 1) % p->num_subchannels;
-      p->checking_connectivity = grpc_subchannel_check_connectivity(
-          p->subchannels[p->checking_subchannel]);
-      add_interested_parties_locked(p);
-      goto loop;
-    case GRPC_CHANNEL_CONNECTING:
-    case GRPC_CHANNEL_IDLE:
+
+  if (p->shutdown) {
+    unref = 1;
+  } else if (p->selected != NULL) {
+    grpc_connectivity_state_set(&p->state_tracker, p->checking_connectivity,
+                                "selected_changed");
+    if (p->checking_connectivity != GRPC_CHANNEL_FATAL_FAILURE) {
       grpc_subchannel_notify_on_state_change(
-          p->subchannels[p->checking_subchannel], &p->checking_connectivity,
-          &p->connectivity_changed);
-      break;
-    case GRPC_CHANNEL_FATAL_FAILURE:
-      del_interested_parties_locked(p);
-      GPR_SWAP(grpc_subchannel *, p->subchannels[p->checking_subchannel],
-               p->subchannels[p->num_subchannels - 1]);
-      p->num_subchannels--;
-      GRPC_SUBCHANNEL_UNREF(p->subchannels[p->num_subchannels], "pick_first");
-      if (p->num_subchannels == 0) {
+          p->selected, &p->checking_connectivity, &p->connectivity_changed);
+    } else {
+      unref = 1;
+    }
+  } else {
+  loop:
+    switch (p->checking_connectivity) {
+      case GRPC_CHANNEL_READY:
+        grpc_connectivity_state_set(&p->state_tracker, GRPC_CHANNEL_READY,
+                                    "connecting_ready");
+        p->selected = p->subchannels[p->checking_subchannel];
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
-          *pp->target = NULL;
+          *pp->target = p->selected;
+          grpc_subchannel_del_interested_party(p->selected, pp->pollset);
           grpc_iomgr_add_delayed_callback(pp->on_complete, 1);
           gpr_free(pp);
         }
-        unref = 1;
-      } else {
-        p->checking_subchannel %= p->num_subchannels;
+        grpc_subchannel_notify_on_state_change(
+            p->selected, &p->checking_connectivity, &p->connectivity_changed);
+        break;
+      case GRPC_CHANNEL_TRANSIENT_FAILURE:
+        grpc_connectivity_state_set(&p->state_tracker,
+                                    GRPC_CHANNEL_TRANSIENT_FAILURE,
+                                    "connecting_transient_failure");
+        del_interested_parties_locked(p);
+        p->checking_subchannel =
+            (p->checking_subchannel + 1) % p->num_subchannels;
         p->checking_connectivity = grpc_subchannel_check_connectivity(
             p->subchannels[p->checking_subchannel]);
         add_interested_parties_locked(p);
-        goto loop;
-      }
+        if (p->checking_connectivity == GRPC_CHANNEL_TRANSIENT_FAILURE) {
+          grpc_subchannel_notify_on_state_change(
+              p->subchannels[p->checking_subchannel], &p->checking_connectivity,
+              &p->connectivity_changed);
+        } else {
+          goto loop;
+        }
+        break;
+      case GRPC_CHANNEL_CONNECTING:
+      case GRPC_CHANNEL_IDLE:
+        grpc_connectivity_state_set(&p->state_tracker, p->checking_connectivity,
+                                    "connecting_changed");
+        grpc_subchannel_notify_on_state_change(
+            p->subchannels[p->checking_subchannel], &p->checking_connectivity,
+            &p->connectivity_changed);
+        break;
+      case GRPC_CHANNEL_FATAL_FAILURE:
+        del_interested_parties_locked(p);
+        GPR_SWAP(grpc_subchannel *, p->subchannels[p->checking_subchannel],
+                 p->subchannels[p->num_subchannels - 1]);
+        p->num_subchannels--;
+        GRPC_SUBCHANNEL_UNREF(p->subchannels[p->num_subchannels], "pick_first");
+        if (p->num_subchannels == 0) {
+          grpc_connectivity_state_set(&p->state_tracker,
+                                      GRPC_CHANNEL_FATAL_FAILURE,
+                                      "no_more_channels");
+          while ((pp = p->pending_picks)) {
+            p->pending_picks = pp->next;
+            *pp->target = NULL;
+            grpc_iomgr_add_delayed_callback(pp->on_complete, 1);
+            gpr_free(pp);
+          }
+          unref = 1;
+        } else {
+          grpc_connectivity_state_set(&p->state_tracker,
+                                      GRPC_CHANNEL_TRANSIENT_FAILURE,
+                                      "subchannel_failed");
+          p->checking_subchannel %= p->num_subchannels;
+          p->checking_connectivity = grpc_subchannel_check_connectivity(
+              p->subchannels[p->checking_subchannel]);
+          add_interested_parties_locked(p);
+          goto loop;
+        }
+    }
   }
+
   gpr_mu_unlock(&p->mu);
 
   if (unref) {
@@ -249,8 +306,13 @@ static void pf_notify_on_state_change(grpc_lb_policy *pol,
 }
 
 static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = {
-    pf_destroy,   pf_shutdown,           pf_pick,
-    pf_broadcast, pf_check_connectivity, pf_notify_on_state_change};
+    pf_destroy,
+    pf_shutdown,
+    pf_pick,
+    pf_exit_idle,
+    pf_broadcast,
+    pf_check_connectivity,
+    pf_notify_on_state_change};
 
 grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
                                                  size_t num_subchannels) {
@@ -260,6 +322,8 @@ grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
   grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable);
   p->subchannels = gpr_malloc(sizeof(grpc_subchannel *) * num_subchannels);
   p->num_subchannels = num_subchannels;
+  grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE,
+                               "pick_first");
   memcpy(p->subchannels, subchannels,
          sizeof(grpc_subchannel *) * num_subchannels);
   grpc_iomgr_closure_init(&p->connectivity_changed, pf_connectivity_changed, p);
diff --git a/src/core/client_config/lb_policies/pick_first.h b/src/core/client_config/lb_policies/pick_first.h
index 94c2a9f0c7..31394985e5 100644
--- a/src/core/client_config/lb_policies/pick_first.h
+++ b/src/core/client_config/lb_policies/pick_first.h
@@ -36,6 +36,8 @@
 
 #include "src/core/client_config/lb_policy.h"
 
+/** Returns a load balancing policy instance that picks up the first subchannel
+ *  from \a subchannels to succesfully connect */
 grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
                                                  size_t num_subchannels);
 
diff --git a/src/core/client_config/lb_policy.c b/src/core/client_config/lb_policy.c
index 6d1c788742..90ec44432f 100644
--- a/src/core/client_config/lb_policy.c
+++ b/src/core/client_config/lb_policy.c
@@ -77,3 +77,18 @@ void grpc_lb_policy_pick(grpc_lb_policy *policy, grpc_pollset *pollset,
 void grpc_lb_policy_broadcast(grpc_lb_policy *policy, grpc_transport_op *op) {
   policy->vtable->broadcast(policy, op);
 }
+
+void grpc_lb_policy_exit_idle(grpc_lb_policy *policy) {
+  policy->vtable->exit_idle(policy);
+}
+
+void grpc_lb_policy_notify_on_state_change(grpc_lb_policy *policy,
+                                           grpc_connectivity_state *state,
+                                           grpc_iomgr_closure *closure) {
+  policy->vtable->notify_on_state_change(policy, state, closure);
+}
+
+grpc_connectivity_state grpc_lb_policy_check_connectivity(
+    grpc_lb_policy *policy) {
+  return policy->vtable->check_connectivity(policy);
+}
diff --git a/src/core/client_config/lb_policy.h b/src/core/client_config/lb_policy.h
index a468f761cc..3f7ca8f28d 100644
--- a/src/core/client_config/lb_policy.h
+++ b/src/core/client_config/lb_policy.h
@@ -59,6 +59,9 @@ struct grpc_lb_policy_vtable {
                grpc_metadata_batch *initial_metadata, grpc_subchannel **target,
                grpc_iomgr_closure *on_complete);
 
+  /** try to enter a READY connectivity state */
+  void (*exit_idle)(grpc_lb_policy *policy);
+
   /** broadcast a transport op to all subchannels */
   void (*broadcast)(grpc_lb_policy *policy, grpc_transport_op *op);
 
@@ -106,4 +109,13 @@ void grpc_lb_policy_pick(grpc_lb_policy *policy, grpc_pollset *pollset,
 
 void grpc_lb_policy_broadcast(grpc_lb_policy *policy, grpc_transport_op *op);
 
+void grpc_lb_policy_exit_idle(grpc_lb_policy *policy);
+
+void grpc_lb_policy_notify_on_state_change(grpc_lb_policy *policy,
+                                           grpc_connectivity_state *state,
+                                           grpc_iomgr_closure *closure);
+
+grpc_connectivity_state grpc_lb_policy_check_connectivity(
+    grpc_lb_policy *policy);
+
 #endif /* GRPC_INTERNAL_CORE_CONFIG_LB_POLICY_H */
diff --git a/src/core/client_config/resolvers/dns_resolver.c b/src/core/client_config/resolvers/dns_resolver.c
index ac401bc4d3..827b1a2be5 100644
--- a/src/core/client_config/resolvers/dns_resolver.c
+++ b/src/core/client_config/resolvers/dns_resolver.c
@@ -36,9 +36,11 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/host_port.h>
 #include <grpc/support/string_util.h>
 
 #include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h"
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/support/string.h"
 
@@ -201,6 +203,9 @@ static grpc_resolver *dns_create(
     grpc_subchannel_factory *subchannel_factory) {
   dns_resolver *r;
   const char *path = uri->path;
+  grpc_arg default_host_arg;
+  char *host;
+  char *port;
 
   if (0 != strcmp(uri->authority, "")) {
     gpr_log(GPR_ERROR, "authority based uri's not supported");
@@ -209,6 +214,16 @@ static grpc_resolver *dns_create(
 
   if (path[0] == '/') ++path;
 
+  gpr_split_host_port(path, &host, &port);
+
+  default_host_arg.type = GRPC_ARG_STRING;
+  default_host_arg.key = GRPC_ARG_DEFAULT_AUTHORITY;
+  default_host_arg.value.string = host;
+  subchannel_factory = grpc_subchannel_factory_add_channel_arg(subchannel_factory, &default_host_arg);
+
+  gpr_free(host);
+  gpr_free(port);
+
   r = gpr_malloc(sizeof(dns_resolver));
   memset(r, 0, sizeof(*r));
   gpr_ref_init(&r->refs, 1);
@@ -218,7 +233,6 @@ static grpc_resolver *dns_create(
   r->default_port = gpr_strdup(default_port);
   r->subchannel_factory = subchannel_factory;
   r->lb_policy_factory = lb_policy_factory;
-  grpc_subchannel_factory_ref(subchannel_factory);
   return &r->base;
 }
 
diff --git a/src/core/client_config/resolvers/sockaddr_resolver.c b/src/core/client_config/resolvers/sockaddr_resolver.c
new file mode 100644
index 0000000000..74584e7e2c
--- /dev/null
+++ b/src/core/client_config/resolvers/sockaddr_resolver.c
@@ -0,0 +1,299 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/client_config/resolvers/sockaddr_resolver.h"
+
+#include <stdio.h>
+#include <string.h>
+#ifdef GPR_POSIX_SOCKET
+#include <sys/un.h>
+#endif
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/host_port.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/iomgr/resolve_address.h"
+#include "src/core/support/string.h"
+
+typedef struct {
+  /** base class: must be first */
+  grpc_resolver base;
+  /** refcount */
+  gpr_refcount refs;
+  /** subchannel factory */
+  grpc_subchannel_factory *subchannel_factory;
+  /** load balancing policy factory */
+  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                       size_t num_subchannels);
+
+  /** the address that we've 'resolved' */
+  struct sockaddr_storage addr;
+  int addr_len;
+
+  /** mutex guarding the rest of the state */
+  gpr_mu mu;
+  /** have we published? */
+  int published;
+  /** pending next completion, or NULL */
+  grpc_iomgr_closure *next_completion;
+  /** target config address for next completion */
+  grpc_client_config **target_config;
+} sockaddr_resolver;
+
+static void sockaddr_destroy(grpc_resolver *r);
+
+static void sockaddr_maybe_finish_next_locked(sockaddr_resolver *r);
+
+static void sockaddr_shutdown(grpc_resolver *r);
+static void sockaddr_channel_saw_error(grpc_resolver *r,
+                                       struct sockaddr *failing_address,
+                                       int failing_address_len);
+static void sockaddr_next(grpc_resolver *r, grpc_client_config **target_config,
+                          grpc_iomgr_closure *on_complete);
+
+static const grpc_resolver_vtable sockaddr_resolver_vtable = {
+    sockaddr_destroy, sockaddr_shutdown, sockaddr_channel_saw_error,
+    sockaddr_next};
+
+static void sockaddr_shutdown(grpc_resolver *resolver) {
+  sockaddr_resolver *r = (sockaddr_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  if (r->next_completion != NULL) {
+    *r->target_config = NULL;
+    /* TODO(ctiller): add delayed callback */
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+  }
+  gpr_mu_unlock(&r->mu);
+}
+
+static void sockaddr_channel_saw_error(grpc_resolver *resolver,
+                                       struct sockaddr *sa, int len) {}
+
+static void sockaddr_next(grpc_resolver *resolver,
+                          grpc_client_config **target_config,
+                          grpc_iomgr_closure *on_complete) {
+  sockaddr_resolver *r = (sockaddr_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  GPR_ASSERT(!r->next_completion);
+  r->next_completion = on_complete;
+  r->target_config = target_config;
+  sockaddr_maybe_finish_next_locked(r);
+  gpr_mu_unlock(&r->mu);
+}
+
+static void sockaddr_maybe_finish_next_locked(sockaddr_resolver *r) {
+  grpc_client_config *cfg;
+  grpc_lb_policy *lb_policy;
+  grpc_subchannel *subchannel;
+  grpc_subchannel_args args;
+
+  if (r->next_completion != NULL && !r->published) {
+    cfg = grpc_client_config_create();
+    memset(&args, 0, sizeof(args));
+    args.addr = (struct sockaddr *)&r->addr;
+    args.addr_len = r->addr_len;
+    subchannel =
+        grpc_subchannel_factory_create_subchannel(r->subchannel_factory, &args);
+    lb_policy = r->lb_policy_factory(&subchannel, 1);
+    grpc_client_config_set_lb_policy(cfg, lb_policy);
+    GRPC_LB_POLICY_UNREF(lb_policy, "unix");
+    r->published = 1;
+    *r->target_config = cfg;
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+  }
+}
+
+static void sockaddr_destroy(grpc_resolver *gr) {
+  sockaddr_resolver *r = (sockaddr_resolver *)gr;
+  gpr_mu_destroy(&r->mu);
+  grpc_subchannel_factory_unref(r->subchannel_factory);
+  gpr_free(r);
+}
+
+#ifdef GPR_POSIX_SOCKET
+static int parse_unix(grpc_uri *uri, struct sockaddr_storage *addr, int *len) {
+  struct sockaddr_un *un = (struct sockaddr_un *)addr;
+
+  un->sun_family = AF_UNIX;
+  strcpy(un->sun_path, uri->path);
+  *len = strlen(un->sun_path) + sizeof(un->sun_family) + 1;
+
+  return 1;
+}
+#endif
+
+static int parse_ipv4(grpc_uri *uri, struct sockaddr_storage *addr, int *len) {
+  const char *host_port = uri->path;
+  char *host;
+  char *port;
+  int port_num;
+  int result = 0;
+  struct sockaddr_in *in = (struct sockaddr_in *)addr;
+
+  if (*host_port == '/') ++host_port;
+  if (!gpr_split_host_port(host_port, &host, &port)) {
+    return 0;
+  }
+
+  memset(in, 0, sizeof(*in));
+  *len = sizeof(*in);
+  in->sin_family = AF_INET;
+  if (inet_pton(AF_INET, host, &in->sin_addr) == 0) {
+    gpr_log(GPR_ERROR, "invalid ipv4 address: '%s'", host);
+    goto done;
+  }
+
+  if (port != NULL) {
+    if (sscanf(port, "%d", &port_num) != 1 || port_num < 0 ||
+        port_num > 65535) {
+      gpr_log(GPR_ERROR, "invalid ipv4 port: '%s'", port);
+      goto done;
+    }
+    in->sin_port = htons(port_num);
+  } else {
+    gpr_log(GPR_ERROR, "no port given for ipv4 scheme");
+    goto done;
+  }
+
+  result = 1;
+done:
+  gpr_free(host);
+  gpr_free(port);
+  return result;
+}
+
+static int parse_ipv6(grpc_uri *uri, struct sockaddr_storage *addr, int *len) {
+  const char *host_port = uri->path;
+  char *host;
+  char *port;
+  int port_num;
+  int result = 0;
+  struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)addr;
+
+  if (*host_port == '/') ++host_port;
+  if (!gpr_split_host_port(host_port, &host, &port)) {
+    return 0;
+  }
+
+  memset(in6, 0, sizeof(*in6));
+  *len = sizeof(*in6);
+  in6->sin6_family = AF_INET6;
+  if (inet_pton(AF_INET6, host, &in6->sin6_addr) == 0) {
+    gpr_log(GPR_ERROR, "invalid ipv6 address: '%s'", host);
+    goto done;
+  }
+
+  if (port != NULL) {
+    if (sscanf(port, "%d", &port_num) != 1 || port_num < 0 ||
+        port_num > 65535) {
+      gpr_log(GPR_ERROR, "invalid ipv6 port: '%s'", port);
+      goto done;
+    }
+    in6->sin6_port = htons(port_num);
+  } else {
+    gpr_log(GPR_ERROR, "no port given for ipv6 scheme");
+    goto done;
+  }
+
+  result = 1;
+done:
+  gpr_free(host);
+  gpr_free(port);
+  return result;
+}
+
+static grpc_resolver *sockaddr_create(
+    grpc_uri *uri,
+    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                         size_t num_subchannels),
+    grpc_subchannel_factory *subchannel_factory,
+    int parse(grpc_uri *uri, struct sockaddr_storage *dst, int *len)) {
+  sockaddr_resolver *r;
+
+  if (0 != strcmp(uri->authority, "")) {
+    gpr_log(GPR_ERROR, "authority based uri's not supported");
+    return NULL;
+  }
+
+  r = gpr_malloc(sizeof(sockaddr_resolver));
+  memset(r, 0, sizeof(*r));
+  if (!parse(uri, &r->addr, &r->addr_len)) {
+    gpr_free(r);
+    return NULL;
+  }
+
+  gpr_ref_init(&r->refs, 1);
+  gpr_mu_init(&r->mu);
+  grpc_resolver_init(&r->base, &sockaddr_resolver_vtable);
+  r->subchannel_factory = subchannel_factory;
+  r->lb_policy_factory = lb_policy_factory;
+
+  grpc_subchannel_factory_ref(subchannel_factory);
+  return &r->base;
+}
+
+/*
+ * FACTORY
+ */
+
+static void sockaddr_factory_ref(grpc_resolver_factory *factory) {}
+
+static void sockaddr_factory_unref(grpc_resolver_factory *factory) {}
+
+#define DECL_FACTORY(name)                                            \
+  static grpc_resolver *name##_factory_create_resolver(               \
+      grpc_resolver_factory *factory, grpc_uri *uri,                  \
+      grpc_subchannel_factory *subchannel_factory) {                  \
+    return sockaddr_create(uri, grpc_create_pick_first_lb_policy,     \
+                           subchannel_factory, parse_##name);         \
+  }                                                                   \
+  static const grpc_resolver_factory_vtable name##_factory_vtable = { \
+      sockaddr_factory_ref, sockaddr_factory_unref,                   \
+      name##_factory_create_resolver};                                \
+  static grpc_resolver_factory name##_resolver_factory = {            \
+      &name##_factory_vtable};                                        \
+  grpc_resolver_factory *grpc_##name##_resolver_factory_create() {    \
+    return &name##_resolver_factory;                                  \
+  }
+
+#ifdef GPR_POSIX_SOCKET
+DECL_FACTORY(unix)
+#endif
+DECL_FACTORY(ipv4)
+DECL_FACTORY(ipv6)
diff --git a/src/core/client_config/resolvers/unix_resolver_posix.h b/src/core/client_config/resolvers/sockaddr_resolver.h
index 57ace59e21..1b7a18f9c2 100644
--- a/src/core/client_config/resolvers/unix_resolver_posix.h
+++ b/src/core/client_config/resolvers/sockaddr_resolver.h
@@ -38,7 +38,13 @@
 
 #include "src/core/client_config/resolver_factory.h"
 
+grpc_resolver_factory *grpc_ipv4_resolver_factory_create(void);
+
+grpc_resolver_factory *grpc_ipv6_resolver_factory_create(void);
+
+#ifdef GPR_POSIX_SOCKET
 /** Create a unix resolver factory */
 grpc_resolver_factory *grpc_unix_resolver_factory_create(void);
+#endif
 
 #endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_UNIX_RESOLVER_H */
diff --git a/src/core/client_config/resolvers/unix_resolver_posix.c b/src/core/client_config/resolvers/unix_resolver_posix.c
deleted file mode 100644
index be515d2689..0000000000
--- a/src/core/client_config/resolvers/unix_resolver_posix.c
+++ /dev/null
@@ -1,195 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-#ifdef GPR_POSIX_SOCKET
-
-#include "src/core/client_config/resolvers/unix_resolver_posix.h"
-
-#include <string.h>
-#include <sys/un.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
-
-#include "src/core/client_config/lb_policies/pick_first.h"
-#include "src/core/iomgr/resolve_address.h"
-#include "src/core/support/string.h"
-
-typedef struct {
-  /** base class: must be first */
-  grpc_resolver base;
-  /** refcount */
-  gpr_refcount refs;
-  /** subchannel factory */
-  grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy factory */
-  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                       size_t num_subchannels);
-
-  /** the address that we've 'resolved' */
-  struct sockaddr_un addr;
-  int addr_len;
-
-  /** mutex guarding the rest of the state */
-  gpr_mu mu;
-  /** have we published? */
-  int published;
-  /** pending next completion, or NULL */
-  grpc_iomgr_closure *next_completion;
-  /** target config address for next completion */
-  grpc_client_config **target_config;
-} unix_resolver;
-
-static void unix_destroy(grpc_resolver *r);
-
-static void unix_maybe_finish_next_locked(unix_resolver *r);
-
-static void unix_shutdown(grpc_resolver *r);
-static void unix_channel_saw_error(grpc_resolver *r,
-                                   struct sockaddr *failing_address,
-                                   int failing_address_len);
-static void unix_next(grpc_resolver *r, grpc_client_config **target_config,
-                      grpc_iomgr_closure *on_complete);
-
-static const grpc_resolver_vtable unix_resolver_vtable = {
-    unix_destroy, unix_shutdown, unix_channel_saw_error, unix_next};
-
-static void unix_shutdown(grpc_resolver *resolver) {
-  unix_resolver *r = (unix_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  if (r->next_completion != NULL) {
-    *r->target_config = NULL;
-    /* TODO(ctiller): add delayed callback */
-    grpc_iomgr_add_callback(r->next_completion);
-    r->next_completion = NULL;
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void unix_channel_saw_error(grpc_resolver *resolver, struct sockaddr *sa,
-                                   int len) {}
-
-static void unix_next(grpc_resolver *resolver,
-                      grpc_client_config **target_config,
-                      grpc_iomgr_closure *on_complete) {
-  unix_resolver *r = (unix_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(!r->next_completion);
-  r->next_completion = on_complete;
-  r->target_config = target_config;
-  unix_maybe_finish_next_locked(r);
-  gpr_mu_unlock(&r->mu);
-}
-
-static void unix_maybe_finish_next_locked(unix_resolver *r) {
-  grpc_client_config *cfg;
-  grpc_lb_policy *lb_policy;
-  grpc_subchannel *subchannel;
-  grpc_subchannel_args args;
-
-  if (r->next_completion != NULL && !r->published) {
-    cfg = grpc_client_config_create();
-    memset(&args, 0, sizeof(args));
-    args.addr = (struct sockaddr *)&r->addr;
-    args.addr_len = r->addr_len;
-    subchannel =
-        grpc_subchannel_factory_create_subchannel(r->subchannel_factory, &args);
-    lb_policy = r->lb_policy_factory(&subchannel, 1);
-    grpc_client_config_set_lb_policy(cfg, lb_policy);
-    GRPC_LB_POLICY_UNREF(lb_policy, "unix");
-    r->published = 1;
-    *r->target_config = cfg;
-    grpc_iomgr_add_callback(r->next_completion);
-    r->next_completion = NULL;
-  }
-}
-
-static void unix_destroy(grpc_resolver *gr) {
-  unix_resolver *r = (unix_resolver *)gr;
-  gpr_mu_destroy(&r->mu);
-  grpc_subchannel_factory_unref(r->subchannel_factory);
-  gpr_free(r);
-}
-
-static grpc_resolver *unix_create(
-    grpc_uri *uri,
-    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                         size_t num_subchannels),
-    grpc_subchannel_factory *subchannel_factory) {
-  unix_resolver *r;
-
-  if (0 != strcmp(uri->authority, "")) {
-    gpr_log(GPR_ERROR, "authority based uri's not supported");
-    return NULL;
-  }
-
-  r = gpr_malloc(sizeof(unix_resolver));
-  memset(r, 0, sizeof(*r));
-  gpr_ref_init(&r->refs, 1);
-  gpr_mu_init(&r->mu);
-  grpc_resolver_init(&r->base, &unix_resolver_vtable);
-  r->subchannel_factory = subchannel_factory;
-  r->lb_policy_factory = lb_policy_factory;
-
-  r->addr.sun_family = AF_UNIX;
-  strcpy(r->addr.sun_path, uri->path);
-  r->addr_len = strlen(r->addr.sun_path) + sizeof(r->addr.sun_family) + 1;
-
-  grpc_subchannel_factory_ref(subchannel_factory);
-  return &r->base;
-}
-
-/*
- * FACTORY
- */
-
-static void unix_factory_ref(grpc_resolver_factory *factory) {}
-
-static void unix_factory_unref(grpc_resolver_factory *factory) {}
-
-static grpc_resolver *unix_factory_create_resolver(
-    grpc_resolver_factory *factory, grpc_uri *uri,
-    grpc_subchannel_factory *subchannel_factory) {
-  return unix_create(uri, grpc_create_pick_first_lb_policy, subchannel_factory);
-}
-
-static const grpc_resolver_factory_vtable unix_factory_vtable = {
-    unix_factory_ref, unix_factory_unref, unix_factory_create_resolver};
-static grpc_resolver_factory unix_resolver_factory = {&unix_factory_vtable};
-
-grpc_resolver_factory *grpc_unix_resolver_factory_create() {
-  return &unix_resolver_factory;
-}
-
-#endif
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 8cdad1015f..17773bd2f4 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -38,9 +38,17 @@
 #include <grpc/support/alloc.h>
 
 #include "src/core/channel/channel_args.h"
+#include "src/core/channel/client_channel.h"
 #include "src/core/channel/connected_channel.h"
 #include "src/core/iomgr/alarm.h"
 #include "src/core/transport/connectivity_state.h"
+#include "src/core/surface/channel.h"
+
+#define GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS 20
+#define GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS 1
+#define GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS 120
+#define GRPC_SUBCHANNEL_RECONNECT_JITTER 0.2
 
 typedef struct {
   /* all fields protected by subchannel->mu */
@@ -94,8 +102,10 @@ struct grpc_subchannel {
   grpc_iomgr_closure connected;
 
   /** pollset_set tracking who's interested in a connection
-      being setup */
-  grpc_pollset_set pollset_set;
+      being setup - owned by the master channel (in particular the
+     client_channel
+      filter there-in) */
+  grpc_pollset_set *pollset_set;
 
   /** mutex protecting remaining elements */
   gpr_mu mu;
@@ -121,6 +131,8 @@ struct grpc_subchannel {
   int have_alarm;
   /** our alarm */
   grpc_alarm alarm;
+  /** current random value */
+  gpr_uint32 random;
 };
 
 struct grpc_subchannel_call {
@@ -132,7 +144,8 @@ struct grpc_subchannel_call {
 #define CHANNEL_STACK_FROM_CONNECTION(con) ((grpc_channel_stack *)((con) + 1))
 
 static grpc_subchannel_call *create_call(connection *con);
-static void connectivity_state_changed_locked(grpc_subchannel *c);
+static void connectivity_state_changed_locked(grpc_subchannel *c,
+                                              const char *reason);
 static grpc_connectivity_state compute_connectivity_locked(grpc_subchannel *c);
 static gpr_timespec compute_connect_deadline(grpc_subchannel *c);
 static void subchannel_connected(void *subchannel, int iomgr_success);
@@ -244,7 +257,6 @@ static void subchannel_destroy(grpc_subchannel *c) {
   grpc_channel_args_destroy(c->args);
   gpr_free(c->addr);
   grpc_mdctx_unref(c->mdctx);
-  grpc_pollset_set_destroy(&c->pollset_set);
   grpc_connectivity_state_destroy(&c->state_tracker);
   grpc_connector_unref(c->connector);
   gpr_free(c);
@@ -252,17 +264,23 @@ static void subchannel_destroy(grpc_subchannel *c) {
 
 void grpc_subchannel_add_interested_party(grpc_subchannel *c,
                                           grpc_pollset *pollset) {
-  grpc_pollset_set_add_pollset(&c->pollset_set, pollset);
+  grpc_pollset_set_add_pollset(c->pollset_set, pollset);
 }
 
 void grpc_subchannel_del_interested_party(grpc_subchannel *c,
                                           grpc_pollset *pollset) {
-  grpc_pollset_set_del_pollset(&c->pollset_set, pollset);
+  grpc_pollset_set_del_pollset(c->pollset_set, pollset);
+}
+
+static gpr_uint32 random_seed() {
+  return (gpr_uint32)(gpr_time_to_millis(gpr_now(GPR_CLOCK_MONOTONIC)));
 }
 
 grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
                                         grpc_subchannel_args *args) {
   grpc_subchannel *c = gpr_malloc(sizeof(*c));
+  grpc_channel_element *parent_elem = grpc_channel_stack_last_element(
+      grpc_channel_get_channel_stack(args->master));
   memset(c, 0, sizeof(*c));
   c->refs = 1;
   c->connector = connector;
@@ -277,10 +295,12 @@ grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
   c->args = grpc_channel_args_copy(args->args);
   c->mdctx = args->mdctx;
   c->master = args->master;
+  c->pollset_set = grpc_client_channel_get_connecting_pollset_set(parent_elem);
+  c->random = random_seed();
   grpc_mdctx_ref(c->mdctx);
-  grpc_pollset_set_init(&c->pollset_set);
   grpc_iomgr_closure_init(&c->connected, subchannel_connected, c);
-  grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE);
+  grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE,
+                               "subchannel");
   gpr_mu_init(&c->mu);
   return c;
 }
@@ -288,7 +308,7 @@ grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
 static void continue_connect(grpc_subchannel *c) {
   grpc_connect_in_args args;
 
-  args.interested_parties = &c->pollset_set;
+  args.interested_parties = c->pollset_set;
   args.addr = c->addr;
   args.addr_len = c->addr_len;
   args.deadline = compute_connect_deadline(c);
@@ -300,15 +320,16 @@ static void continue_connect(grpc_subchannel *c) {
 }
 
 static void start_connect(grpc_subchannel *c) {
-  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
-  c->next_attempt = now;
-  c->backoff_delta = gpr_time_from_seconds(1);
-
+  c->backoff_delta = gpr_time_from_seconds(
+      GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS, GPR_TIMESPAN);
+  c->next_attempt = gpr_time_add(
+      gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
   continue_connect(c);
 }
 
 static void continue_creating_call(void *arg, int iomgr_success) {
   waiting_for_connect *w4c = arg;
+  grpc_subchannel_del_interested_party(w4c->subchannel, w4c->pollset);
   grpc_subchannel_create_call(w4c->subchannel, w4c->pollset, w4c->target,
                               w4c->notify);
   GRPC_SUBCHANNEL_UNREF(w4c->subchannel, "waiting_for_connect");
@@ -341,9 +362,10 @@ void grpc_subchannel_create_call(grpc_subchannel *c, grpc_pollset *pollset,
     grpc_subchannel_add_interested_party(c, pollset);
     if (!c->connecting) {
       c->connecting = 1;
-      connectivity_state_changed_locked(c);
+      connectivity_state_changed_locked(c, "create_call");
       /* released by connection */
       SUBCHANNEL_REF_LOCKED(c, "connecting");
+      GRPC_CHANNEL_INTERNAL_REF(c->master, "connecting");
       gpr_mu_unlock(&c->mu);
 
       start_connect(c);
@@ -372,7 +394,8 @@ void grpc_subchannel_notify_on_state_change(grpc_subchannel *c,
     c->connecting = 1;
     /* released by connection */
     SUBCHANNEL_REF_LOCKED(c, "connecting");
-    connectivity_state_changed_locked(c);
+    GRPC_CHANNEL_INTERNAL_REF(c->master, "connecting");
+    connectivity_state_changed_locked(c, "state_change");
   }
   gpr_mu_unlock(&c->mu);
   if (do_connect) {
@@ -388,7 +411,7 @@ void grpc_subchannel_process_transport_op(grpc_subchannel *c,
   gpr_mu_lock(&c->mu);
   if (op->disconnect) {
     c->disconnected = 1;
-    connectivity_state_changed_locked(c);
+    connectivity_state_changed_locked(c, "disconnect");
     if (c->have_alarm) {
       cancel_alarm = 1;
     }
@@ -456,13 +479,15 @@ static void on_state_changed(void *p, int iomgr_success) {
         destroy_connection = sw->subchannel->active;
       }
       sw->subchannel->active = NULL;
-      grpc_connectivity_state_set(&c->state_tracker,
-                                  GRPC_CHANNEL_TRANSIENT_FAILURE);
+      grpc_connectivity_state_set(
+          &c->state_tracker, c->disconnected ? GRPC_CHANNEL_FATAL_FAILURE
+                                             : GRPC_CHANNEL_TRANSIENT_FAILURE,
+          "connection_failed");
       break;
   }
 
 done:
-  connectivity_state_changed_locked(c);
+  connectivity_state_changed_locked(c, "transport_state_changed");
   destroy = SUBCHANNEL_UNREF_LOCKED(c, "state_watcher");
   gpr_free(sw);
   gpr_mu_unlock(mu);
@@ -486,6 +511,8 @@ static void publish_transport(grpc_subchannel *c) {
   connection *destroy_connection = NULL;
   grpc_channel_element *elem;
 
+  gpr_log(GPR_DEBUG, "publish_transport: %p", c->master);
+
   /* build final filter list */
   num_filters = c->num_filters + c->connecting_result.num_filters + 1;
   filters = gpr_malloc(sizeof(*filters) * num_filters);
@@ -519,6 +546,8 @@ static void publish_transport(grpc_subchannel *c) {
     gpr_free(sw);
     gpr_free(filters);
     grpc_channel_stack_destroy(stk);
+    GRPC_CHANNEL_INTERNAL_UNREF(c->master, "connecting");
+    GRPC_SUBCHANNEL_UNREF(c, "connecting");
     return;
   }
 
@@ -536,14 +565,16 @@ static void publish_transport(grpc_subchannel *c) {
   memset(&op, 0, sizeof(op));
   op.connectivity_state = &sw->connectivity_state;
   op.on_connectivity_state_change = &sw->closure;
+  op.bind_pollset_set = c->pollset_set;
   SUBCHANNEL_REF_LOCKED(c, "state_watcher");
+  GRPC_CHANNEL_INTERNAL_UNREF(c->master, "connecting");
   GPR_ASSERT(!SUBCHANNEL_UNREF_LOCKED(c, "connecting"));
   elem =
       grpc_channel_stack_element(CHANNEL_STACK_FROM_CONNECTION(c->active), 0);
   elem->filter->start_transport_op(elem, &op);
 
   /* signal completion */
-  connectivity_state_changed_locked(c);
+  connectivity_state_changed_locked(c, "connected");
   while ((w4c = c->waiting)) {
     c->waiting = w4c->next;
     grpc_iomgr_add_callback(&w4c->continuation);
@@ -558,6 +589,35 @@ static void publish_transport(grpc_subchannel *c) {
   }
 }
 
+/* Generate a random number between 0 and 1. */
+static double generate_uniform_random_number(grpc_subchannel *c) {
+  c->random = (1103515245 * c->random + 12345) % ((gpr_uint32)1 << 31);
+  return c->random / (double)((gpr_uint32)1 << 31);
+}
+
+/* Update backoff_delta and next_attempt in subchannel */
+static void update_reconnect_parameters(grpc_subchannel *c) {
+  gpr_int32 backoff_delta_millis, jitter;
+  gpr_int32 max_backoff_millis =
+      GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000;
+  double jitter_range;
+  backoff_delta_millis =
+      (gpr_int32)(gpr_time_to_millis(c->backoff_delta) *
+                  GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER);
+  if (backoff_delta_millis > max_backoff_millis) {
+    backoff_delta_millis = max_backoff_millis;
+  }
+  c->backoff_delta = gpr_time_from_millis(backoff_delta_millis, GPR_TIMESPAN);
+  c->next_attempt =
+      gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
+
+  jitter_range = GRPC_SUBCHANNEL_RECONNECT_JITTER * backoff_delta_millis;
+  jitter =
+      (gpr_int32)((2 * generate_uniform_random_number(c) - 1) * jitter_range);
+  c->next_attempt =
+      gpr_time_add(c->next_attempt, gpr_time_from_millis(jitter, GPR_TIMESPAN));
+}
+
 static void on_alarm(void *arg, int iomgr_success) {
   grpc_subchannel *c = arg;
   gpr_mu_lock(&c->mu);
@@ -565,11 +625,13 @@ static void on_alarm(void *arg, int iomgr_success) {
   if (c->disconnected) {
     iomgr_success = 0;
   }
-  connectivity_state_changed_locked(c);
+  connectivity_state_changed_locked(c, "alarm");
   gpr_mu_unlock(&c->mu);
   if (iomgr_success) {
+    update_reconnect_parameters(c);
     continue_connect(c);
   } else {
+    GRPC_CHANNEL_INTERNAL_UNREF(c->master, "connecting");
     GRPC_SUBCHANNEL_UNREF(c, "connecting");
   }
 }
@@ -579,19 +641,25 @@ static void subchannel_connected(void *arg, int iomgr_success) {
   if (c->connecting_result.transport != NULL) {
     publish_transport(c);
   } else {
+    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
     gpr_mu_lock(&c->mu);
-    connectivity_state_changed_locked(c);
     GPR_ASSERT(!c->have_alarm);
     c->have_alarm = 1;
-    c->next_attempt = gpr_time_add(c->next_attempt, c->backoff_delta);
-    c->backoff_delta = gpr_time_add(c->backoff_delta, c->backoff_delta);
-    grpc_alarm_init(&c->alarm, c->next_attempt, on_alarm, c, gpr_now(GPR_CLOCK_REALTIME));
+    connectivity_state_changed_locked(c, "connect_failed");
+    grpc_alarm_init(&c->alarm, c->next_attempt, on_alarm, c, now);
     gpr_mu_unlock(&c->mu);
   }
 }
 
 static gpr_timespec compute_connect_deadline(grpc_subchannel *c) {
-  return gpr_time_add(c->next_attempt, c->backoff_delta);
+  gpr_timespec current_deadline =
+      gpr_time_add(c->next_attempt, c->backoff_delta);
+  gpr_timespec min_deadline = gpr_time_add(
+      gpr_now(GPR_CLOCK_MONOTONIC),
+      gpr_time_from_seconds(GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS,
+                            GPR_TIMESPAN));
+  return gpr_time_cmp(current_deadline, min_deadline) > 0 ? current_deadline
+                                                          : min_deadline;
 }
 
 static grpc_connectivity_state compute_connectivity_locked(grpc_subchannel *c) {
@@ -610,9 +678,10 @@ static grpc_connectivity_state compute_connectivity_locked(grpc_subchannel *c) {
   return GRPC_CHANNEL_IDLE;
 }
 
-static void connectivity_state_changed_locked(grpc_subchannel *c) {
+static void connectivity_state_changed_locked(grpc_subchannel *c,
+                                              const char *reason) {
   grpc_connectivity_state current = compute_connectivity_locked(c);
-  grpc_connectivity_state_set(&c->state_tracker, current);
+  grpc_connectivity_state_set(&c->state_tracker, current, reason);
 }
 
 /*
@@ -640,6 +709,12 @@ void grpc_subchannel_call_unref(
   }
 }
 
+char *grpc_subchannel_call_get_peer(grpc_subchannel_call *call) {
+  grpc_call_stack *call_stack = SUBCHANNEL_CALL_TO_CALL_STACK(call);
+  grpc_call_element *top_elem = grpc_call_stack_element(call_stack, 0);
+  return top_elem->filter->get_peer(top_elem);
+}
+
 void grpc_subchannel_call_process_op(grpc_subchannel_call *call,
                                      grpc_transport_stream_op *op) {
   grpc_call_stack *call_stack = SUBCHANNEL_CALL_TO_CALL_STACK(call);
diff --git a/src/core/client_config/subchannel.h b/src/core/client_config/subchannel.h
index a23a623277..d1cd33b2af 100644
--- a/src/core/client_config/subchannel.h
+++ b/src/core/client_config/subchannel.h
@@ -100,6 +100,9 @@ void grpc_subchannel_del_interested_party(grpc_subchannel *channel,
 void grpc_subchannel_call_process_op(grpc_subchannel_call *subchannel_call,
                                      grpc_transport_stream_op *op);
 
+/** continue querying for peer */
+char *grpc_subchannel_call_get_peer(grpc_subchannel_call *subchannel_call);
+
 struct grpc_subchannel_args {
   /** Channel filters for this channel - wrapped factories will likely
       want to mutate this */
diff --git a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c
new file mode 100644
index 0000000000..7dc6d99ebe
--- /dev/null
+++ b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c
@@ -0,0 +1,43 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h"
+#include "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h"
+
+grpc_subchannel_factory *grpc_subchannel_factory_add_channel_arg(
+		grpc_subchannel_factory *input, const grpc_arg *arg) {
+	grpc_channel_args args;
+	args.num_args = 1;
+	args.args = (grpc_arg *)arg;
+	return grpc_subchannel_factory_merge_channel_args(input, &args);
+}
diff --git a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h
new file mode 100644
index 0000000000..1937623374
--- /dev/null
+++ b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h
@@ -0,0 +1,45 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H
+
+#include "src/core/client_config/subchannel_factory.h"
+
+/** Takes a subchannel factory, returns a new one that mutates incoming
+    channel_args by adding a new argument; ownership of input, arg is retained
+    by the caller. */
+grpc_subchannel_factory *grpc_subchannel_factory_add_channel_arg(
+		grpc_subchannel_factory *input, const grpc_arg *arg);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H */
diff --git a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c
new file mode 100644
index 0000000000..7e028857ac
--- /dev/null
+++ b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c
@@ -0,0 +1,84 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h"
+#include <grpc/support/alloc.h>
+#include "src/core/channel/channel_args.h"
+
+typedef struct {
+  grpc_subchannel_factory base;
+  gpr_refcount refs;
+  grpc_subchannel_factory *wrapped;
+  grpc_channel_args *merge_args;
+} merge_args_factory;
+
+static void merge_args_factory_ref(grpc_subchannel_factory *scf) {
+  merge_args_factory *f = (merge_args_factory *)scf;
+  gpr_ref(&f->refs);
+}
+
+static void merge_args_factory_unref(grpc_subchannel_factory *scf) {
+  merge_args_factory *f = (merge_args_factory *)scf;
+  if (gpr_unref(&f->refs)) {
+  	grpc_subchannel_factory_unref(f->wrapped);
+    grpc_channel_args_destroy(f->merge_args);
+    gpr_free(f);
+  }
+}
+
+static grpc_subchannel *merge_args_factory_create_subchannel(
+    grpc_subchannel_factory *scf, grpc_subchannel_args *args) {
+  merge_args_factory *f = (merge_args_factory *)scf;
+  grpc_channel_args *final_args =
+      grpc_channel_args_merge(args->args, f->merge_args);
+  grpc_subchannel *s;
+  args->args = final_args;
+  s = grpc_subchannel_factory_create_subchannel(f->wrapped, args);
+  grpc_channel_args_destroy(final_args);
+  return s;
+}
+
+static const grpc_subchannel_factory_vtable merge_args_factory_vtable = {
+    merge_args_factory_ref, merge_args_factory_unref,
+    merge_args_factory_create_subchannel};
+
+grpc_subchannel_factory *grpc_subchannel_factory_merge_channel_args(
+		grpc_subchannel_factory *input, const grpc_channel_args *args) {
+  merge_args_factory *f = gpr_malloc(sizeof(*f));
+  f->base.vtable = &merge_args_factory_vtable;
+  gpr_ref_init(&f->refs, 1);
+  grpc_subchannel_factory_ref(input);
+  f->wrapped = input;
+  f->merge_args = grpc_channel_args_copy(args);
+  return &f->base;
+}
diff --git a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h
new file mode 100644
index 0000000000..73a03b752f
--- /dev/null
+++ b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h
@@ -0,0 +1,45 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H
+
+#include "src/core/client_config/subchannel_factory.h"
+
+/** Takes a subchannel factory, returns a new one that mutates incoming
+    channel_args by adding a new argument; ownership of input, args is retained
+    by the caller. */
+grpc_subchannel_factory *grpc_subchannel_factory_merge_channel_args(
+		grpc_subchannel_factory *input, const grpc_channel_args *args);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H */
diff --git a/src/core/compression/algorithm.c b/src/core/compression/algorithm.c
index 4db48df6cb..e426241d0a 100644
--- a/src/core/compression/algorithm.c
+++ b/src/core/compression/algorithm.c
@@ -32,21 +32,39 @@
  */
 
 #include <stdlib.h>
+#include <string.h>
 #include <grpc/compression.h>
 
-const char *grpc_compression_algorithm_name(
-    grpc_compression_algorithm algorithm) {
+int grpc_compression_algorithm_parse(const char* name,
+                                     grpc_compression_algorithm *algorithm) {
+  if (strcmp(name, "none") == 0) {
+    *algorithm = GRPC_COMPRESS_NONE;
+  } else if (strcmp(name, "gzip") == 0) {
+    *algorithm = GRPC_COMPRESS_GZIP;
+  } else if (strcmp(name, "deflate") == 0) {
+    *algorithm = GRPC_COMPRESS_DEFLATE;
+  } else {
+    return 0;
+  }
+  return 1;
+}
+
+int grpc_compression_algorithm_name(grpc_compression_algorithm algorithm,
+                                    char **name) {
   switch (algorithm) {
     case GRPC_COMPRESS_NONE:
-      return "none";
+      *name = "none";
+      break;
     case GRPC_COMPRESS_DEFLATE:
-      return "deflate";
+      *name = "deflate";
+      break;
     case GRPC_COMPRESS_GZIP:
-      return "gzip";
-    case GRPC_COMPRESS_ALGORITHMS_COUNT:
-      return "error";
+      *name = "gzip";
+      break;
+    default:
+      return 0;
   }
-  return "error";
+  return 1;
 }
 
 /* TODO(dgq): Add the ability to specify parameters to the individual
@@ -65,3 +83,15 @@ grpc_compression_algorithm grpc_compression_algorithm_for_level(
       abort();
   }
 }
+
+grpc_compression_level grpc_compression_level_for_algorithm(
+    grpc_compression_algorithm algorithm) {
+  grpc_compression_level clevel;
+  for (clevel = GRPC_COMPRESS_LEVEL_NONE; clevel < GRPC_COMPRESS_LEVEL_COUNT;
+       ++clevel) {
+    if (grpc_compression_algorithm_for_level(clevel) == algorithm) {
+      return clevel;
+    }
+  }
+  abort();
+}
diff --git a/src/core/iomgr/alarm.c b/src/core/iomgr/alarm.c
index 5860834de3..68d33b9cf6 100644
--- a/src/core/iomgr/alarm.c
+++ b/src/core/iomgr/alarm.c
@@ -36,6 +36,7 @@
 #include "src/core/iomgr/alarm_heap.h"
 #include "src/core/iomgr/alarm_internal.h"
 #include "src/core/iomgr/time_averaged_stats.h"
+#include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/useful.h>
 
@@ -67,6 +68,7 @@ typedef struct {
 static gpr_mu g_mu;
 /* Allow only one run_some_expired_alarms at once */
 static gpr_mu g_checker_mu;
+static gpr_clock_type g_clock_type;
 static shard_type g_shards[NUM_SHARDS];
 /* Protected by g_mu */
 static shard_type *g_shard_queue[NUM_SHARDS];
@@ -85,6 +87,7 @@ void grpc_alarm_list_init(gpr_timespec now) {
 
   gpr_mu_init(&g_mu);
   gpr_mu_init(&g_checker_mu);
+  g_clock_type = now.clock_type;
 
   for (i = 0; i < NUM_SHARDS; i++) {
     shard_type *shard = &g_shards[i];
@@ -102,7 +105,8 @@ void grpc_alarm_list_init(gpr_timespec now) {
 
 void grpc_alarm_list_shutdown(void) {
   int i;
-  while (run_some_expired_alarms(NULL, gpr_inf_future, NULL, 0))
+  while (run_some_expired_alarms(NULL, gpr_inf_future(g_clock_type), NULL,
+                                 0))
     ;
   for (i = 0; i < NUM_SHARDS; i++) {
     shard_type *shard = &g_shards[i];
@@ -127,6 +131,7 @@ static gpr_timespec dbl_to_ts(double d) {
   gpr_timespec ts;
   ts.tv_sec = d;
   ts.tv_nsec = 1e9 * (d - ts.tv_sec);
+  ts.clock_type = GPR_TIMESPAN;
   return ts;
 }
 
@@ -173,6 +178,8 @@ void grpc_alarm_init(grpc_alarm *alarm, gpr_timespec deadline,
                      gpr_timespec now) {
   int is_first_alarm = 0;
   shard_type *shard = &g_shards[shard_idx(alarm)];
+  GPR_ASSERT(deadline.clock_type == g_clock_type);
+  GPR_ASSERT(now.clock_type == g_clock_type);
   alarm->cb = alarm_cb;
   alarm->cb_arg = alarm_cb_arg;
   alarm->deadline = deadline;
@@ -353,7 +360,10 @@ static int run_some_expired_alarms(gpr_mu *drop_mu, gpr_timespec now,
 }
 
 int grpc_alarm_check(gpr_mu *drop_mu, gpr_timespec now, gpr_timespec *next) {
-  return run_some_expired_alarms(drop_mu, now, next, 1);
+  GPR_ASSERT(now.clock_type == g_clock_type);
+  return run_some_expired_alarms(
+      drop_mu, now, next, 
+      gpr_time_cmp(now, gpr_inf_future(now.clock_type)) != 0);
 }
 
 gpr_timespec grpc_alarm_list_next_timeout(void) {
diff --git a/src/core/iomgr/endpoint.c b/src/core/iomgr/endpoint.c
index 96487958a7..744fe7656c 100644
--- a/src/core/iomgr/endpoint.c
+++ b/src/core/iomgr/endpoint.c
@@ -50,6 +50,14 @@ void grpc_endpoint_add_to_pollset(grpc_endpoint *ep, grpc_pollset *pollset) {
   ep->vtable->add_to_pollset(ep, pollset);
 }
 
+void grpc_endpoint_add_to_pollset_set(grpc_endpoint *ep, grpc_pollset_set *pollset_set) {
+  ep->vtable->add_to_pollset_set(ep, pollset_set);
+}
+
 void grpc_endpoint_shutdown(grpc_endpoint *ep) { ep->vtable->shutdown(ep); }
 
 void grpc_endpoint_destroy(grpc_endpoint *ep) { ep->vtable->destroy(ep); }
+
+char *grpc_endpoint_get_peer(grpc_endpoint *ep) {
+  return ep->vtable->get_peer(ep);
+}
diff --git a/src/core/iomgr/endpoint.h b/src/core/iomgr/endpoint.h
index 881e851800..a2216925f9 100644
--- a/src/core/iomgr/endpoint.h
+++ b/src/core/iomgr/endpoint.h
@@ -35,6 +35,7 @@
 #define GRPC_INTERNAL_CORE_IOMGR_ENDPOINT_H
 
 #include "src/core/iomgr/pollset.h"
+#include "src/core/iomgr/pollset_set.h"
 #include <grpc/support/slice.h>
 #include <grpc/support/time.h>
 
@@ -70,14 +71,18 @@ struct grpc_endpoint_vtable {
                                       size_t nslices, grpc_endpoint_write_cb cb,
                                       void *user_data);
   void (*add_to_pollset)(grpc_endpoint *ep, grpc_pollset *pollset);
+  void (*add_to_pollset_set)(grpc_endpoint *ep, grpc_pollset_set *pollset);
   void (*shutdown)(grpc_endpoint *ep);
   void (*destroy)(grpc_endpoint *ep);
+  char *(*get_peer)(grpc_endpoint *ep);
 };
 
 /* When data is available on the connection, calls the callback with slices. */
 void grpc_endpoint_notify_on_read(grpc_endpoint *ep, grpc_endpoint_read_cb cb,
                                   void *user_data);
 
+char *grpc_endpoint_get_peer(grpc_endpoint *ep);
+
 /* Write slices out to the socket.
 
    If the connection is ready for more data after the end of the call, it
@@ -98,6 +103,7 @@ void grpc_endpoint_destroy(grpc_endpoint *ep);
 /* Add an endpoint to a pollset, so that when the pollset is polled, events from
    this endpoint are considered */
 void grpc_endpoint_add_to_pollset(grpc_endpoint *ep, grpc_pollset *pollset);
+void grpc_endpoint_add_to_pollset_set(grpc_endpoint *ep, grpc_pollset_set *pollset_set);
 
 struct grpc_endpoint {
   const grpc_endpoint_vtable *vtable;
diff --git a/src/core/iomgr/endpoint_pair_posix.c b/src/core/iomgr/endpoint_pair_posix.c
index fa2d2555d6..deae9c6875 100644
--- a/src/core/iomgr/endpoint_pair_posix.c
+++ b/src/core/iomgr/endpoint_pair_posix.c
@@ -66,12 +66,12 @@ grpc_endpoint_pair grpc_iomgr_create_endpoint_pair(const char *name,
   create_sockets(sv);
 
   gpr_asprintf(&final_name, "%s:client", name);
-  p.client =
-      grpc_tcp_create(grpc_fd_create(sv[1], final_name), read_slice_size);
+  p.client = grpc_tcp_create(grpc_fd_create(sv[1], final_name), read_slice_size,
+                             "socketpair-server");
   gpr_free(final_name);
   gpr_asprintf(&final_name, "%s:server", name);
-  p.server =
-      grpc_tcp_create(grpc_fd_create(sv[0], final_name), read_slice_size);
+  p.server = grpc_tcp_create(grpc_fd_create(sv[0], final_name), read_slice_size,
+                             "socketpair-client");
   gpr_free(final_name);
   return p;
 }
diff --git a/src/core/iomgr/endpoint_pair_windows.c b/src/core/iomgr/endpoint_pair_windows.c
index c6790b2937..e8295df8b3 100644
--- a/src/core/iomgr/endpoint_pair_windows.c
+++ b/src/core/iomgr/endpoint_pair_windows.c
@@ -81,8 +81,10 @@ grpc_endpoint_pair grpc_iomgr_create_endpoint_pair(const char *name, size_t read
   SOCKET sv[2];
   grpc_endpoint_pair p;
   create_sockets(sv);
-  p.client = grpc_tcp_create(grpc_winsocket_create(sv[1], "endpoint:client"));
-  p.server = grpc_tcp_create(grpc_winsocket_create(sv[0], "endpoint:server"));
+  p.client = grpc_tcp_create(grpc_winsocket_create(sv[1], "endpoint:client"),
+                             "endpoint:server");
+  p.server = grpc_tcp_create(grpc_winsocket_create(sv[0], "endpoint:server"),
+                             "endpoint:client");
   return p;
 }
 
diff --git a/src/core/iomgr/fd_posix.c b/src/core/iomgr/fd_posix.c
index 6ad377ce1c..a2df838d4a 100644
--- a/src/core/iomgr/fd_posix.c
+++ b/src/core/iomgr/fd_posix.c
@@ -102,6 +102,7 @@ static grpc_fd *alloc_fd(int fd) {
   r->freelist_next = NULL;
   r->read_watcher = r->write_watcher = NULL;
   r->on_done_closure = NULL;
+  r->closed = 0;
   return r;
 }
 
@@ -209,6 +210,8 @@ void grpc_fd_orphan(grpc_fd *fd, grpc_iomgr_closure *on_done,
   REF_BY(fd, 1, reason); /* remove active status, but keep referenced */
   gpr_mu_lock(&fd->watcher_mu);
   if (!has_watchers(fd)) {
+    GPR_ASSERT(!fd->closed);
+    fd->closed = 1;
     close(fd->fd);
     if (fd->on_done_closure) {
       grpc_iomgr_add_callback(fd->on_done_closure);
@@ -426,7 +429,8 @@ void grpc_fd_end_poll(grpc_fd_watcher *watcher, int got_read, int got_write) {
   if (kick) {
     maybe_wake_one_watcher_locked(fd);
   }
-  if (grpc_fd_is_orphaned(fd) && !has_watchers(fd)) {
+  if (grpc_fd_is_orphaned(fd) && !has_watchers(fd) && !fd->closed) {
+    fd->closed = 1;
     close(fd->fd);
     if (fd->on_done_closure != NULL) {
       grpc_iomgr_add_callback(fd->on_done_closure);
diff --git a/src/core/iomgr/fd_posix.h b/src/core/iomgr/fd_posix.h
index 94d0019fa4..4e8e267ffd 100644
--- a/src/core/iomgr/fd_posix.h
+++ b/src/core/iomgr/fd_posix.h
@@ -60,6 +60,7 @@ struct grpc_fd {
 
   gpr_mu set_state_mu;
   gpr_atm shutdown;
+  int closed;
 
   /* The watcher list.
 
diff --git a/src/core/iomgr/iocp_windows.c b/src/core/iomgr/iocp_windows.c
index 3d3a193d00..8741241fb8 100644
--- a/src/core/iomgr/iocp_windows.c
+++ b/src/core/iomgr/iocp_windows.c
@@ -157,7 +157,7 @@ void grpc_iocp_shutdown(void) {
   BOOL success;
   gpr_event_set(&g_shutdown_iocp, (void *)1);
   grpc_iocp_kick();
-  gpr_event_wait(&g_iocp_done, gpr_inf_future);
+  gpr_event_wait(&g_iocp_done, gpr_inf_future(GPR_CLOCK_REALTIME));
   success = CloseHandle(g_iocp);
   GPR_ASSERT(success);
 }
diff --git a/src/core/iomgr/iomgr.c b/src/core/iomgr/iomgr.c
index cca92d3b32..fdc9adf4af 100644
--- a/src/core/iomgr/iomgr.c
+++ b/src/core/iomgr/iomgr.c
@@ -57,9 +57,9 @@ static grpc_iomgr_object g_root_object;
 static void background_callback_executor(void *ignored) {
   gpr_mu_lock(&g_mu);
   while (!g_shutdown) {
-    gpr_timespec deadline = gpr_inf_future;
-    gpr_timespec short_deadline =
-        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
+    gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
+    gpr_timespec short_deadline = gpr_time_add(
+        gpr_now(GPR_CLOCK_MONOTONIC), gpr_time_from_millis(100, GPR_TIMESPAN));
     if (g_cbs_head) {
       grpc_iomgr_closure *closure = g_cbs_head;
       g_cbs_head = closure->next;
@@ -67,7 +67,7 @@ static void background_callback_executor(void *ignored) {
       gpr_mu_unlock(&g_mu);
       closure->cb(closure->cb_arg, closure->success);
       gpr_mu_lock(&g_mu);
-    } else if (grpc_alarm_check(&g_mu, gpr_now(GPR_CLOCK_REALTIME),
+    } else if (grpc_alarm_check(&g_mu, gpr_now(GPR_CLOCK_MONOTONIC),
                                 &deadline)) {
     } else {
       gpr_mu_unlock(&g_mu);
@@ -88,9 +88,10 @@ void grpc_kick_poller(void) {
 
 void grpc_iomgr_init(void) {
   gpr_thd_id id;
+  g_shutdown = 0;
   gpr_mu_init(&g_mu);
   gpr_cv_init(&g_rcv);
-  grpc_alarm_list_init(gpr_now(GPR_CLOCK_REALTIME));
+  grpc_alarm_list_init(gpr_now(GPR_CLOCK_MONOTONIC));
   g_root_object.next = g_root_object.prev = &g_root_object;
   g_root_object.name = "root";
   grpc_iomgr_platform_init();
@@ -110,8 +111,8 @@ static size_t count_objects(void) {
 void grpc_iomgr_shutdown(void) {
   grpc_iomgr_object *obj;
   grpc_iomgr_closure *closure;
-  gpr_timespec shutdown_deadline =
-      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10));
+  gpr_timespec shutdown_deadline = gpr_time_add(
+      gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10, GPR_TIMESPAN));
   gpr_timespec last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
 
   gpr_mu_lock(&g_mu);
@@ -119,7 +120,7 @@ void grpc_iomgr_shutdown(void) {
   while (g_cbs_head != NULL || g_root_object.next != &g_root_object) {
     if (gpr_time_cmp(
             gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), last_warning_time),
-            gpr_time_from_seconds(1)) >= 0) {
+            gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
       if (g_cbs_head != NULL && g_root_object.next != &g_root_object) {
         gpr_log(GPR_DEBUG,
                 "Waiting for %d iomgr objects to be destroyed and executing "
@@ -145,14 +146,13 @@ void grpc_iomgr_shutdown(void) {
       } while (g_cbs_head);
       continue;
     }
-    if (grpc_alarm_check(&g_mu, gpr_inf_future, NULL)) {
-      gpr_log(GPR_DEBUG, "got late alarm");
+    if (grpc_alarm_check(&g_mu, gpr_inf_future(GPR_CLOCK_MONOTONIC), NULL)) {
       continue;
     }
     if (g_root_object.next != &g_root_object) {
       int timeout = 0;
-      gpr_timespec short_deadline =
-          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
+      gpr_timespec short_deadline = gpr_time_add(
+          gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100, GPR_TIMESPAN));
       while (gpr_cv_wait(&g_rcv, &g_mu, short_deadline) && g_cbs_head == NULL) {
         if (gpr_time_cmp(gpr_now(GPR_CLOCK_REALTIME), shutdown_deadline) > 0) {
           timeout = 1;
@@ -174,7 +174,8 @@ void grpc_iomgr_shutdown(void) {
   gpr_mu_unlock(&g_mu);
 
   grpc_kick_poller();
-  gpr_event_wait(&g_background_callback_executor_done, gpr_inf_future);
+  gpr_event_wait(&g_background_callback_executor_done,
+                 gpr_inf_future(GPR_CLOCK_REALTIME));
 
   grpc_alarm_list_shutdown();
 
diff --git a/src/core/iomgr/pollset_multipoller_with_epoll.c b/src/core/iomgr/pollset_multipoller_with_epoll.c
index 3746c8edaf..d697b59e4c 100644
--- a/src/core/iomgr/pollset_multipoller_with_epoll.c
+++ b/src/core/iomgr/pollset_multipoller_with_epoll.c
@@ -50,12 +50,17 @@ typedef struct {
 } pollset_hdr;
 
 static void multipoll_with_epoll_pollset_add_fd(grpc_pollset *pollset,
-                                                grpc_fd *fd) {
+                                                grpc_fd *fd,
+                                                int and_unlock_pollset) {
   pollset_hdr *h = pollset->data.ptr;
   struct epoll_event ev;
   int err;
   grpc_fd_watcher watcher;
 
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
+
   /* We pretend to be polling whilst adding an fd to keep the fd from being
      closed during the add. This may result in a spurious wakeup being assigned
      to this pollset whilst adding, but that should be benign. */
@@ -76,9 +81,15 @@ static void multipoll_with_epoll_pollset_add_fd(grpc_pollset *pollset,
 }
 
 static void multipoll_with_epoll_pollset_del_fd(grpc_pollset *pollset,
-                                                grpc_fd *fd) {
+                                                grpc_fd *fd,
+                                                int and_unlock_pollset) {
   pollset_hdr *h = pollset->data.ptr;
   int err;
+
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
+
   /* Note that this can race with concurrent poll, but that should be fine since
    * at worst it creates a spurious read event on a reused grpc_fd object. */
   err = epoll_ctl(h->epoll_fd, EPOLL_CTL_DEL, fd->fd, NULL);
@@ -183,7 +194,7 @@ static void epoll_become_multipoller(grpc_pollset *pollset, grpc_fd **fds,
     abort();
   }
   for (i = 0; i < nfds; i++) {
-    multipoll_with_epoll_pollset_add_fd(pollset, fds[i]);
+    multipoll_with_epoll_pollset_add_fd(pollset, fds[i], 0);
   }
 
   grpc_wakeup_fd_create(&h->wakeup_fd);
diff --git a/src/core/iomgr/pollset_multipoller_with_poll_posix.c b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
index 7b717bd159..0084e83953 100644
--- a/src/core/iomgr/pollset_multipoller_with_poll_posix.c
+++ b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
@@ -66,12 +66,13 @@ typedef struct {
 } pollset_hdr;
 
 static void multipoll_with_poll_pollset_add_fd(grpc_pollset *pollset,
-                                               grpc_fd *fd) {
+                                               grpc_fd *fd,
+                                               int and_unlock_pollset) {
   size_t i;
   pollset_hdr *h = pollset->data.ptr;
   /* TODO(ctiller): this is O(num_fds^2); maybe switch to a hash set here */
   for (i = 0; i < h->fd_count; i++) {
-    if (h->fds[i] == fd) return;
+    if (h->fds[i] == fd) goto exit;
   }
   if (h->fd_count == h->fd_capacity) {
     h->fd_capacity = GPR_MAX(h->fd_capacity + 8, h->fd_count * 3 / 2);
@@ -79,10 +80,15 @@ static void multipoll_with_poll_pollset_add_fd(grpc_pollset *pollset,
   }
   h->fds[h->fd_count++] = fd;
   GRPC_FD_REF(fd, "multipoller");
+exit:  
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
 }
 
 static void multipoll_with_poll_pollset_del_fd(grpc_pollset *pollset,
-                                               grpc_fd *fd) {
+                                               grpc_fd *fd,
+                                               int and_unlock_pollset) {
   /* will get removed next poll cycle */
   pollset_hdr *h = pollset->data.ptr;
   if (h->del_count == h->del_capacity) {
@@ -91,6 +97,9 @@ static void multipoll_with_poll_pollset_del_fd(grpc_pollset *pollset,
   }
   h->dels[h->del_count++] = fd;
   GRPC_FD_REF(fd, "multipoller_del");
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
 }
 
 static void end_polling(grpc_pollset *pollset) {
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index 85101764d2..c8646af615 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -105,14 +105,28 @@ void grpc_pollset_init(grpc_pollset *pollset) {
 
 void grpc_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
   gpr_mu_lock(&pollset->mu);
-  pollset->vtable->add_fd(pollset, fd);
+  pollset->vtable->add_fd(pollset, fd, 1);
+  /* the following (enabled only in debug) will reacquire and then release
+     our lock - meaning that if the unlocking flag passed to del_fd above is
+     not respected, the code will deadlock (in a way that we have a chance of
+     debugging) */
+#ifndef NDEBUG
+  gpr_mu_lock(&pollset->mu);
   gpr_mu_unlock(&pollset->mu);
+#endif
 }
 
 void grpc_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {
   gpr_mu_lock(&pollset->mu);
-  pollset->vtable->del_fd(pollset, fd);
+  pollset->vtable->del_fd(pollset, fd, 1);
+  /* the following (enabled only in debug) will reacquire and then release
+     our lock - meaning that if the unlocking flag passed to del_fd above is
+     not respected, the code will deadlock (in a way that we have a chance of
+     debugging) */
+#ifndef NDEBUG
+  gpr_mu_lock(&pollset->mu);
   gpr_mu_unlock(&pollset->mu);
+#endif
 }
 
 static void finish_shutdown(grpc_pollset *pollset) {
@@ -122,7 +136,7 @@ static void finish_shutdown(grpc_pollset *pollset) {
 
 int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   /* pollset->mu already held */
-  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
+  gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0;
   }
@@ -191,17 +205,17 @@ int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
                                          gpr_timespec now) {
   gpr_timespec timeout;
   static const int max_spin_polling_us = 10;
-  if (gpr_time_cmp(deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) == 0) {
     return -1;
   }
-  if (gpr_time_cmp(
-          deadline,
-          gpr_time_add(now, gpr_time_from_micros(max_spin_polling_us))) <= 0) {
+  if (gpr_time_cmp(deadline, gpr_time_add(now, gpr_time_from_micros(
+                                                   max_spin_polling_us,
+                                                   GPR_TIMESPAN))) <= 0) {
     return 0;
   }
   timeout = gpr_time_sub(deadline, now);
-  return gpr_time_to_millis(
-      gpr_time_add(timeout, gpr_time_from_nanos(GPR_NS_PER_SEC - 1)));
+  return gpr_time_to_millis(gpr_time_add(
+      timeout, gpr_time_from_nanos(GPR_NS_PER_SEC - 1, GPR_TIMESPAN)));
 }
 
 /*
@@ -257,7 +271,7 @@ static void basic_do_promote(void *args, int success) {
   } else if (grpc_fd_is_orphaned(fd)) {
     /* Don't try to add it to anything, we'll drop our ref on it below */
   } else if (pollset->vtable != original_vtable) {
-    pollset->vtable->add_fd(pollset, fd);
+    pollset->vtable->add_fd(pollset, fd, 0);
   } else if (fd != pollset->data.ptr) {
     grpc_fd *fds[2];
     fds[0] = pollset->data.ptr;
@@ -287,10 +301,11 @@ static void basic_do_promote(void *args, int success) {
   GRPC_FD_UNREF(fd, "basicpoll_add");
 }
 
-static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
+static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd,
+                                 int and_unlock_pollset) {
   grpc_unary_promote_args *up_args;
   GPR_ASSERT(fd);
-  if (fd == pollset->data.ptr) return;
+  if (fd == pollset->data.ptr) goto exit;
 
   if (!pollset->counter) {
     /* Fast path -- no in flight cbs */
@@ -313,7 +328,7 @@ static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
       pollset->data.ptr = fd;
       GRPC_FD_REF(fd, "basicpoll");
     }
-    return;
+    goto exit;
   }
 
   /* Now we need to promote. This needs to happen when we're not polling. Since
@@ -329,14 +344,24 @@ static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
   grpc_iomgr_add_callback(&up_args->promotion_closure);
 
   grpc_pollset_kick(pollset);
+
+exit:
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
 }
 
-static void basic_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {
+static void basic_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd,
+                                 int and_unlock_pollset) {
   GPR_ASSERT(fd);
   if (fd == pollset->data.ptr) {
     GRPC_FD_UNREF(pollset->data.ptr, "basicpoll");
     pollset->data.ptr = NULL;
   }
+
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
 }
 
 static void basic_pollset_maybe_work(grpc_pollset *pollset,
diff --git a/src/core/iomgr/pollset_posix.h b/src/core/iomgr/pollset_posix.h
index 53585a2886..37de1276d1 100644
--- a/src/core/iomgr/pollset_posix.h
+++ b/src/core/iomgr/pollset_posix.h
@@ -66,8 +66,10 @@ typedef struct grpc_pollset {
 } grpc_pollset;
 
 struct grpc_pollset_vtable {
-  void (*add_fd)(grpc_pollset *pollset, struct grpc_fd *fd);
-  void (*del_fd)(grpc_pollset *pollset, struct grpc_fd *fd);
+  void (*add_fd)(grpc_pollset *pollset, struct grpc_fd *fd,
+                 int and_unlock_pollset);
+  void (*del_fd)(grpc_pollset *pollset, struct grpc_fd *fd,
+                 int and_unlock_pollset);
   void (*maybe_work)(grpc_pollset *pollset, gpr_timespec deadline,
                      gpr_timespec now, int allow_synchronous_callback);
   void (*kick)(grpc_pollset *pollset);
diff --git a/src/core/iomgr/pollset_set.h b/src/core/iomgr/pollset_set.h
index 98e3b552a7..6d73951c70 100644
--- a/src/core/iomgr/pollset_set.h
+++ b/src/core/iomgr/pollset_set.h
@@ -38,7 +38,7 @@
 
 /* A grpc_pollset_set is a set of pollsets that are interested in an
    action. Adding a pollset to a pollset_set automatically adds any
-   fd's (etc) that have been registered with the set_set with that pollset.
+   fd's (etc) that have been registered with the set_set to that pollset.
    Registering fd's automatically adds them to all current pollsets. */
 
 #ifdef GPR_POSIX_SOCKET
diff --git a/src/core/iomgr/pollset_set_posix.c b/src/core/iomgr/pollset_set_posix.c
index 5ff7df1dcd..2076ac70ef 100644
--- a/src/core/iomgr/pollset_set_posix.c
+++ b/src/core/iomgr/pollset_set_posix.c
@@ -60,7 +60,7 @@ void grpc_pollset_set_destroy(grpc_pollset_set *pollset_set) {
 
 void grpc_pollset_set_add_pollset(grpc_pollset_set *pollset_set,
                                   grpc_pollset *pollset) {
-  size_t i;
+  size_t i, j;
   gpr_mu_lock(&pollset_set->mu);
   if (pollset_set->pollset_count == pollset_set->pollset_capacity) {
     pollset_set->pollset_capacity =
@@ -70,9 +70,15 @@ void grpc_pollset_set_add_pollset(grpc_pollset_set *pollset_set,
                                                sizeof(*pollset_set->pollsets));
   }
   pollset_set->pollsets[pollset_set->pollset_count++] = pollset;
-  for (i = 0; i < pollset_set->fd_count; i++) {
-    grpc_pollset_add_fd(pollset, pollset_set->fds[i]);
+  for (i = 0, j = 0; i < pollset_set->fd_count; i++) {
+    if (grpc_fd_is_orphaned(pollset_set->fds[i])) {
+      GRPC_FD_UNREF(pollset_set->fds[i], "pollset");
+    } else {
+      grpc_pollset_add_fd(pollset, pollset_set->fds[i]);
+      pollset_set->fds[j++] = pollset_set->fds[i];
+    }
   }
+  pollset_set->fd_count = j;
   gpr_mu_unlock(&pollset_set->mu);
 }
 
diff --git a/src/core/iomgr/pollset_windows.c b/src/core/iomgr/pollset_windows.c
index 24226cc980..a9c4739c7c 100644
--- a/src/core/iomgr/pollset_windows.c
+++ b/src/core/iomgr/pollset_windows.c
@@ -70,7 +70,7 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {
 
 int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   gpr_timespec now;
-  now = gpr_now(GPR_CLOCK_REALTIME);
+  now = gpr_now(GPR_CLOCK_MONOTONIC);
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0 /* GPR_FALSE */;
   }
diff --git a/src/core/iomgr/sockaddr_utils.c b/src/core/iomgr/sockaddr_utils.c
index e91b94f8c8..71ac12e87b 100644
--- a/src/core/iomgr/sockaddr_utils.c
+++ b/src/core/iomgr/sockaddr_utils.c
@@ -36,12 +36,18 @@
 #include <errno.h>
 #include <string.h>
 
-#include "src/core/support/string.h"
+#ifdef GPR_POSIX_SOCKET
+#include <sys/un.h>
+#endif
+
+#include <grpc/support/alloc.h>
 #include <grpc/support/host_port.h>
 #include <grpc/support/log.h>
 #include <grpc/support/port_platform.h>
 #include <grpc/support/string_util.h>
 
+#include "src/core/support/string.h"
+
 static const gpr_uint8 kV4MappedPrefix[] = {0, 0, 0, 0, 0,    0,
                                             0, 0, 0, 0, 0xff, 0xff};
 
@@ -161,6 +167,31 @@ int grpc_sockaddr_to_string(char **out, const struct sockaddr *addr,
   return ret;
 }
 
+char *grpc_sockaddr_to_uri(const struct sockaddr *addr) {
+  char *temp;
+  char *result;
+
+  switch (addr->sa_family) {
+    case AF_INET:
+      grpc_sockaddr_to_string(&temp, addr, 0);
+      gpr_asprintf(&result, "ipv4:%s", temp);
+      gpr_free(temp);
+      return result;
+    case AF_INET6:
+      grpc_sockaddr_to_string(&temp, addr, 0);
+      gpr_asprintf(&result, "ipv6:%s", temp);
+      gpr_free(temp);
+      return result;
+#ifdef GPR_POSIX_SOCKET
+    case AF_UNIX:
+      gpr_asprintf(&result, "unix:%s", ((struct sockaddr_un *)addr)->sun_path);
+      return result;
+#endif
+  }
+
+  return NULL;
+}
+
 int grpc_sockaddr_get_port(const struct sockaddr *addr) {
   switch (addr->sa_family) {
     case AF_INET:
diff --git a/src/core/iomgr/sockaddr_utils.h b/src/core/iomgr/sockaddr_utils.h
index bdfb83479b..99f1ed54da 100644
--- a/src/core/iomgr/sockaddr_utils.h
+++ b/src/core/iomgr/sockaddr_utils.h
@@ -84,4 +84,6 @@ int grpc_sockaddr_set_port(const struct sockaddr *addr, int port);
 int grpc_sockaddr_to_string(char **out, const struct sockaddr *addr,
                             int normalize);
 
+char *grpc_sockaddr_to_uri(const struct sockaddr *addr);
+
 #endif  /* GRPC_INTERNAL_CORE_IOMGR_SOCKADDR_UTILS_H */
diff --git a/src/core/iomgr/tcp_client_posix.c b/src/core/iomgr/tcp_client_posix.c
index dc0489e64f..9572ce5980 100644
--- a/src/core/iomgr/tcp_client_posix.c
+++ b/src/core/iomgr/tcp_client_posix.c
@@ -64,6 +64,7 @@ typedef struct {
   int refs;
   grpc_iomgr_closure write_closure;
   grpc_pollset_set *interested_parties;
+  char *addr_str;
 } async_connect;
 
 static int prepare_socket(const struct sockaddr *addr, int fd) {
@@ -88,17 +89,18 @@ error:
   return 0;
 }
 
-static void on_alarm(void *acp, int success) {
+static void tc_on_alarm(void *acp, int success) {
   int done;
   async_connect *ac = acp;
   gpr_mu_lock(&ac->mu);
-  if (ac->fd != NULL && success) {
+  if (ac->fd != NULL) {
     grpc_fd_shutdown(ac->fd);
   }
   done = (--ac->refs == 0);
   gpr_mu_unlock(&ac->mu);
   if (done) {
     gpr_mu_destroy(&ac->mu);
+    gpr_free(ac->addr_str);
     gpr_free(ac);
   }
 }
@@ -108,17 +110,25 @@ static void on_writable(void *acp, int success) {
   int so_error = 0;
   socklen_t so_error_size;
   int err;
-  int fd = ac->fd->fd;
   int done;
   grpc_endpoint *ep = NULL;
   void (*cb)(void *arg, grpc_endpoint *tcp) = ac->cb;
   void *cb_arg = ac->cb_arg;
+  grpc_fd *fd;
+
+  gpr_mu_lock(&ac->mu);
+  GPR_ASSERT(ac->fd);
+  fd = ac->fd;
+  ac->fd = NULL;
+  gpr_mu_unlock(&ac->mu);
+
+  grpc_alarm_cancel(&ac->alarm);
 
   gpr_mu_lock(&ac->mu);
   if (success) {
     do {
       so_error_size = sizeof(so_error);
-      err = getsockopt(fd, SOL_SOCKET, SO_ERROR, &so_error, &so_error_size);
+      err = getsockopt(fd->fd, SOL_SOCKET, SO_ERROR, &so_error, &so_error_size);
     } while (err < 0 && errno == EINTR);
     if (err < 0) {
       gpr_log(GPR_ERROR, "getsockopt(ERROR): %s", strerror(errno));
@@ -141,7 +151,7 @@ static void on_writable(void *acp, int success) {
            don't do that! */
         gpr_log(GPR_ERROR, "kernel out of buffers");
         gpr_mu_unlock(&ac->mu);
-        grpc_fd_notify_on_write(ac->fd, &ac->write_closure);
+        grpc_fd_notify_on_write(fd, &ac->write_closure);
         return;
       } else {
         switch (so_error) {
@@ -155,8 +165,9 @@ static void on_writable(void *acp, int success) {
         goto finish;
       }
     } else {
-      grpc_pollset_set_del_fd(ac->interested_parties, ac->fd);
-      ep = grpc_tcp_create(ac->fd, GRPC_TCP_DEFAULT_READ_SLICE_SIZE);
+      grpc_pollset_set_del_fd(ac->interested_parties, fd);
+      ep = grpc_tcp_create(fd, GRPC_TCP_DEFAULT_READ_SLICE_SIZE, ac->addr_str);
+      fd = NULL;
       goto finish;
     }
   } else {
@@ -167,19 +178,17 @@ static void on_writable(void *acp, int success) {
   abort();
 
 finish:
-  if (ep == NULL) {
-    grpc_pollset_set_del_fd(ac->interested_parties, ac->fd);
-    grpc_fd_orphan(ac->fd, NULL, "tcp_client_orphan");
-  } else {
-    ac->fd = NULL;
+  if (fd != NULL) {
+    grpc_pollset_set_del_fd(ac->interested_parties, fd);
+    grpc_fd_orphan(fd, NULL, "tcp_client_orphan");
+    fd = NULL;
   }
   done = (--ac->refs == 0);
   gpr_mu_unlock(&ac->mu);
   if (done) {
     gpr_mu_destroy(&ac->mu);
+    gpr_free(ac->addr_str);
     gpr_free(ac);
-  } else {
-    grpc_alarm_cancel(&ac->alarm);
   }
   cb(cb_arg, ep);
 }
@@ -223,13 +232,13 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *ep),
     err = connect(fd, addr, addr_len);
   } while (err < 0 && errno == EINTR);
 
-  grpc_sockaddr_to_string(&addr_str, addr, 1);
+  addr_str = grpc_sockaddr_to_uri(addr);
   gpr_asprintf(&name, "tcp-client:%s", addr_str);
 
   fdobj = grpc_fd_create(fd, name);
 
   if (err >= 0) {
-    cb(arg, grpc_tcp_create(fdobj, GRPC_TCP_DEFAULT_READ_SLICE_SIZE));
+    cb(arg, grpc_tcp_create(fdobj, GRPC_TCP_DEFAULT_READ_SLICE_SIZE, addr_str));
     goto done;
   }
 
@@ -247,14 +256,16 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *ep),
   ac->cb_arg = arg;
   ac->fd = fdobj;
   ac->interested_parties = interested_parties;
+  ac->addr_str = addr_str;
+  addr_str = NULL;
   gpr_mu_init(&ac->mu);
   ac->refs = 2;
   ac->write_closure.cb = on_writable;
   ac->write_closure.cb_arg = ac;
 
   gpr_mu_lock(&ac->mu);
-  grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac,
-                  gpr_now(GPR_CLOCK_REALTIME));
+  grpc_alarm_init(&ac->alarm, gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC), 
+                  tc_on_alarm, ac, gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_fd_notify_on_write(ac->fd, &ac->write_closure);
   gpr_mu_unlock(&ac->mu);
 
diff --git a/src/core/iomgr/tcp_client_windows.c b/src/core/iomgr/tcp_client_windows.c
index 16741452b9..79a58fe2af 100644
--- a/src/core/iomgr/tcp_client_windows.c
+++ b/src/core/iomgr/tcp_client_windows.c
@@ -58,6 +58,7 @@ typedef struct {
   grpc_winsocket *socket;
   gpr_timespec deadline;
   grpc_alarm alarm;
+  char *addr_name;
   int refs;
   int aborted;
 } async_connect;
@@ -67,6 +68,7 @@ static void async_connect_cleanup(async_connect *ac) {
   gpr_mu_unlock(&ac->mu);
   if (done) {
     gpr_mu_destroy(&ac->mu);
+    gpr_free(ac->addr_name);
     gpr_free(ac);
   }
 }
@@ -107,7 +109,7 @@ static void on_connect(void *acp, int from_iocp) {
       gpr_log(GPR_ERROR, "on_connect error: %s", utf8_message);
       gpr_free(utf8_message);
     } else if (!aborted) {
-      ep = grpc_tcp_create(ac->socket);
+      ep = grpc_tcp_create(ac->socket, ac->addr_name);
     }
   } else {
     gpr_log(GPR_ERROR, "on_connect is shutting down");
@@ -213,10 +215,11 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *tcp),
   ac->socket = socket;
   gpr_mu_init(&ac->mu);
   ac->refs = 2;
+  ac->addr_name = grpc_sockaddr_to_uri(addr);
   ac->aborted = 0;
 
   grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac,
-                  gpr_now(GPR_CLOCK_REALTIME));
+                  gpr_now(GPR_CLOCK_MONOTONIC));
   socket->write_info.outstanding = 1;
   grpc_socket_notify_on_write(socket, on_connect, ac);
   return;
diff --git a/src/core/iomgr/tcp_posix.c b/src/core/iomgr/tcp_posix.c
index b6d6efc9fb..24fee0596f 100644
--- a/src/core/iomgr/tcp_posix.c
+++ b/src/core/iomgr/tcp_posix.c
@@ -44,15 +44,17 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
-#include "src/core/support/string.h"
-#include "src/core/debug/trace.h"
-#include "src/core/profiling/timers.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/slice.h>
+#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
 
+#include "src/core/support/string.h"
+#include "src/core/debug/trace.h"
+#include "src/core/profiling/timers.h"
+
 #ifdef GPR_HAVE_MSG_NOSIGNAL
 #define SENDMSG_FLAGS MSG_NOSIGNAL
 #else
@@ -282,6 +284,8 @@ typedef struct {
   grpc_iomgr_closure write_closure;
 
   grpc_iomgr_closure handle_read_closure;
+
+  char *peer_string;
 } grpc_tcp;
 
 static void grpc_tcp_handle_read(void *arg /* grpc_tcp */, int success);
@@ -296,6 +300,7 @@ static void grpc_tcp_unref(grpc_tcp *tcp) {
   int refcount_zero = gpr_unref(&tcp->refcount);
   if (refcount_zero) {
     grpc_fd_orphan(tcp->em_fd, NULL, "tcp_unref_orphan");
+    gpr_free(tcp->peer_string);
     gpr_free(tcp);
   }
 }
@@ -314,7 +319,7 @@ static void call_read_cb(grpc_tcp *tcp, gpr_slice *slices, size_t nslices,
     gpr_log(GPR_DEBUG, "read: status=%d", status);
     for (i = 0; i < nslices; i++) {
       char *dump = gpr_dump_slice(slices[i], GPR_DUMP_HEX | GPR_DUMP_ASCII);
-      gpr_log(GPR_DEBUG, "READ: %s", dump);
+      gpr_log(GPR_DEBUG, "READ %p: %s", tcp, dump);
       gpr_free(dump);
     }
   }
@@ -443,7 +448,7 @@ static void grpc_tcp_notify_on_read(grpc_endpoint *ep, grpc_endpoint_read_cb cb,
     grpc_fd_notify_on_read(tcp->em_fd, &tcp->read_closure);
   } else {
     tcp->handle_read_closure.cb_arg = tcp;
-    grpc_iomgr_add_callback(&tcp->handle_read_closure);
+    grpc_iomgr_add_delayed_callback(&tcp->handle_read_closure, 1);
   }
 }
 
@@ -567,13 +572,27 @@ static void grpc_tcp_add_to_pollset(grpc_endpoint *ep, grpc_pollset *pollset) {
   grpc_pollset_add_fd(pollset, tcp->em_fd);
 }
 
+static void grpc_tcp_add_to_pollset_set(grpc_endpoint *ep, grpc_pollset_set *pollset_set) {
+  grpc_tcp *tcp = (grpc_tcp *)ep;
+  grpc_pollset_set_add_fd(pollset_set, tcp->em_fd);
+}
+
+static char *grpc_tcp_get_peer(grpc_endpoint *ep) {
+  grpc_tcp *tcp = (grpc_tcp *)ep;
+  return gpr_strdup(tcp->peer_string);
+}
+
 static const grpc_endpoint_vtable vtable = {
-    grpc_tcp_notify_on_read, grpc_tcp_write, grpc_tcp_add_to_pollset,
-    grpc_tcp_shutdown, grpc_tcp_destroy};
+    grpc_tcp_notify_on_read, grpc_tcp_write,
+    grpc_tcp_add_to_pollset, grpc_tcp_add_to_pollset_set,
+    grpc_tcp_shutdown,       grpc_tcp_destroy,
+    grpc_tcp_get_peer};
 
-grpc_endpoint *grpc_tcp_create(grpc_fd *em_fd, size_t slice_size) {
+grpc_endpoint *grpc_tcp_create(grpc_fd *em_fd, size_t slice_size,
+                               const char *peer_string) {
   grpc_tcp *tcp = (grpc_tcp *)gpr_malloc(sizeof(grpc_tcp));
   tcp->base.vtable = &vtable;
+  tcp->peer_string = gpr_strdup(peer_string);
   tcp->fd = em_fd->fd;
   tcp->read_cb = NULL;
   tcp->write_cb = NULL;
diff --git a/src/core/iomgr/tcp_posix.h b/src/core/iomgr/tcp_posix.h
index 44279d5a26..d752feaeea 100644
--- a/src/core/iomgr/tcp_posix.h
+++ b/src/core/iomgr/tcp_posix.h
@@ -53,6 +53,7 @@ extern int grpc_tcp_trace;
 
 /* Create a tcp endpoint given a file desciptor and a read slice size.
    Takes ownership of fd. */
-grpc_endpoint *grpc_tcp_create(grpc_fd *fd, size_t read_slice_size);
+grpc_endpoint *grpc_tcp_create(grpc_fd *fd, size_t read_slice_size,
+                               const char *peer_string);
 
 #endif  /* GRPC_INTERNAL_CORE_IOMGR_TCP_POSIX_H */
diff --git a/src/core/iomgr/tcp_server_posix.c b/src/core/iomgr/tcp_server_posix.c
index 5854031c9b..6399aaadb9 100644
--- a/src/core/iomgr/tcp_server_posix.c
+++ b/src/core/iomgr/tcp_server_posix.c
@@ -142,6 +142,7 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
 
 static void finish_shutdown(grpc_tcp_server *s) {
   s->shutdown_complete(s->shutdown_complete_arg);
+  s->shutdown_complete = NULL;
 
   gpr_mu_destroy(&s->mu);
 
@@ -157,6 +158,7 @@ static void destroyed_port(void *server, int success) {
     gpr_mu_unlock(&s->mu);
     finish_shutdown(s);
   } else {
+    GPR_ASSERT(s->destroyed_ports < s->nports);
     gpr_mu_unlock(&s->mu);
   }
 }
@@ -332,7 +334,7 @@ static void on_read(void *arg, int success) {
 
     grpc_set_socket_no_sigpipe_if_possible(fd);
 
-    grpc_sockaddr_to_string(&addr_str, (struct sockaddr *)&addr, 1);
+    addr_str = grpc_sockaddr_to_uri((struct sockaddr *)&addr);
     gpr_asprintf(&name, "tcp-server-connection:%s", addr_str);
 
     fdobj = grpc_fd_create(fd, name);
@@ -342,8 +344,9 @@ static void on_read(void *arg, int success) {
     for (i = 0; i < sp->server->pollset_count; i++) {
       grpc_pollset_add_fd(sp->server->pollsets[i], fdobj);
     }
-    sp->server->cb(sp->server->cb_arg,
-                   grpc_tcp_create(fdobj, GRPC_TCP_DEFAULT_READ_SLICE_SIZE));
+    sp->server->cb(
+        sp->server->cb_arg,
+        grpc_tcp_create(fdobj, GRPC_TCP_DEFAULT_READ_SLICE_SIZE, addr_str));
 
     gpr_free(name);
     gpr_free(addr_str);
diff --git a/src/core/iomgr/tcp_server_windows.c b/src/core/iomgr/tcp_server_windows.c
index e6e1d1499e..bcd2aa8536 100644
--- a/src/core/iomgr/tcp_server_windows.c
+++ b/src/core/iomgr/tcp_server_windows.c
@@ -79,6 +79,8 @@ struct grpc_tcp_server {
 
   /* active port count: how many ports are actually still listening */
   int active_ports;
+  /* number of iomgr callbacks that have been explicitly scheduled during shutdown */
+  int iomgr_callbacks_pending;
 
   /* all listening ports */
   server_port *ports;
@@ -93,6 +95,7 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
   gpr_mu_init(&s->mu);
   gpr_cv_init(&s->cv);
   s->active_ports = 0;
+  s->iomgr_callbacks_pending = 0;
   s->cb = NULL;
   s->cb_arg = NULL;
   s->ports = gpr_malloc(sizeof(server_port) * INIT_PORT_CAP);
@@ -112,11 +115,11 @@ void grpc_tcp_server_destroy(grpc_tcp_server *s,
   for (i = 0; i < s->nports; i++) {
     server_port *sp = &s->ports[i];
     sp->shutting_down = 1;
-    grpc_winsocket_shutdown(sp->socket);
+    s->iomgr_callbacks_pending += grpc_winsocket_shutdown(sp->socket);
   }
   /* This happens asynchronously. Wait while that happens. */
-  while (s->active_ports) {
-    gpr_cv_wait(&s->cv, &s->mu, gpr_inf_future);
+  while (s->active_ports || s->iomgr_callbacks_pending) {
+    gpr_cv_wait(&s->cv, &s->mu, gpr_inf_future(GPR_CLOCK_REALTIME));
   }
   gpr_mu_unlock(&s->mu);
 
@@ -243,14 +246,27 @@ static void on_accept(void *arg, int from_iocp) {
   SOCKET sock = sp->new_socket;
   grpc_winsocket_callback_info *info = &sp->socket->read_info;
   grpc_endpoint *ep = NULL;
+  struct sockaddr_storage peer_name;
+  char *peer_name_string;
+  char *fd_name;
+  int peer_name_len = sizeof(peer_name);
   DWORD transfered_bytes;
   DWORD flags;
   BOOL wsa_success;
+  int err;
 
   /* The general mechanism for shutting down is to queue abortion calls. While
      this is necessary in the read/write case, it's useless for the accept
-     case. Let's do nothing. */
-  if (!from_iocp) return;
+     case. We only need to adjust the pending callback count */
+  if (!from_iocp) {
+    gpr_mu_lock(&sp->server->mu);
+    GPR_ASSERT(sp->server->iomgr_callbacks_pending > 0);
+    if (0 == --sp->server->iomgr_callbacks_pending) {
+      gpr_cv_broadcast(&sp->server->cv);
+    }
+    gpr_mu_unlock(&sp->server->mu);
+    return;
+  }
 
   /* The IOCP notified us of a completed operation. Let's grab the results,
       and act accordingly. */
@@ -259,11 +275,12 @@ static void on_accept(void *arg, int from_iocp) {
                                             &transfered_bytes, FALSE, &flags);
   if (!wsa_success) {
     if (sp->shutting_down) {
-      /* During the shutdown case, we ARE expecting an error. So that's swell,
+      /* During the shutdown case, we ARE expecting an error. So that's well,
          and we can wake up the shutdown thread. */
       sp->shutting_down = 0;
       sp->socket->read_info.outstanding = 0;
       gpr_mu_lock(&sp->server->mu);
+      GPR_ASSERT(sp->server->active_ports > 0);
       if (0 == --sp->server->active_ports) {
         gpr_cv_broadcast(&sp->server->cv);
       }
@@ -277,8 +294,28 @@ static void on_accept(void *arg, int from_iocp) {
     }
   } else {
     if (!sp->shutting_down) {
-      /* TODO(ctiller): add sockaddr address to label */
-      ep = grpc_tcp_create(grpc_winsocket_create(sock, "server"));
+      peer_name_string = NULL;
+      err = setsockopt(sock, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
+                       (char *)&sp->socket->socket,
+                       sizeof(sp->socket->socket));
+      if (err) {
+        char *utf8_message = gpr_format_message(WSAGetLastError());
+        gpr_log(GPR_ERROR, "setsockopt error: %s", utf8_message);
+        gpr_free(utf8_message);
+      }
+      err = getpeername(sock, (struct sockaddr*)&peer_name, &peer_name_len);
+      if (!err) {
+        peer_name_string = grpc_sockaddr_to_uri((struct sockaddr*)&peer_name);
+      } else {
+        char *utf8_message = gpr_format_message(WSAGetLastError());
+        gpr_log(GPR_ERROR, "getpeername error: %s", utf8_message);
+        gpr_free(utf8_message);
+      }
+      gpr_asprintf(&fd_name, "tcp_server:%s", peer_name_string);
+      ep = grpc_tcp_create(grpc_winsocket_create(sock, fd_name),
+                           peer_name_string);
+      gpr_free(fd_name);
+      gpr_free(peer_name_string);
     }
   }
 
diff --git a/src/core/iomgr/tcp_windows.c b/src/core/iomgr/tcp_windows.c
index 1bf81a73e0..89aa741470 100644
--- a/src/core/iomgr/tcp_windows.c
+++ b/src/core/iomgr/tcp_windows.c
@@ -96,6 +96,8 @@ typedef struct grpc_tcp {
      to protect ourselves when requesting a shutdown. */
   gpr_mu mu;
   int shutting_down;
+
+  char *peer_string;
 } grpc_tcp;
 
 static void tcp_ref(grpc_tcp *tcp) {
@@ -107,6 +109,7 @@ static void tcp_unref(grpc_tcp *tcp) {
     gpr_slice_buffer_destroy(&tcp->write_slices);
     grpc_winsocket_orphan(tcp->socket);
     gpr_mu_destroy(&tcp->mu);
+    gpr_free(tcp->peer_string);
     gpr_free(tcp);
   }
 }
@@ -365,8 +368,17 @@ static grpc_endpoint_write_status win_write(grpc_endpoint *ep,
   return GRPC_ENDPOINT_WRITE_PENDING;
 }
 
-static void win_add_to_pollset(grpc_endpoint *ep, grpc_pollset *pollset) {
-  grpc_tcp *tcp = (grpc_tcp *) ep;
+static void win_add_to_pollset(grpc_endpoint *ep, grpc_pollset *ps) {
+  grpc_tcp *tcp;
+  (void) ps;
+  tcp = (grpc_tcp *) ep;
+  grpc_iocp_add_socket(tcp->socket);
+}
+
+static void win_add_to_pollset_set(grpc_endpoint *ep, grpc_pollset_set *pss) {
+  grpc_tcp *tcp;
+  (void) pss;
+  tcp = (grpc_tcp *) ep;
   grpc_iocp_add_socket(tcp->socket);
 }
 
@@ -393,11 +405,17 @@ static void win_destroy(grpc_endpoint *ep) {
   tcp_unref(tcp);
 }
 
-static grpc_endpoint_vtable vtable = {
-  win_notify_on_read, win_write, win_add_to_pollset, win_shutdown, win_destroy
-};
+static char *win_get_peer(grpc_endpoint *ep) {
+  grpc_tcp *tcp = (grpc_tcp *)ep;
+  return gpr_strdup(tcp->peer_string);
+}
+
+static grpc_endpoint_vtable vtable = {win_notify_on_read, win_write,
+                                      win_add_to_pollset, win_add_to_pollset_set,
+                                      win_shutdown,       win_destroy,
+                                      win_get_peer};
 
-grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket) {
+grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket, char *peer_string) {
   grpc_tcp *tcp = (grpc_tcp *) gpr_malloc(sizeof(grpc_tcp));
   memset(tcp, 0, sizeof(grpc_tcp));
   tcp->base.vtable = &vtable;
@@ -405,6 +423,7 @@ grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket) {
   gpr_mu_init(&tcp->mu);
   gpr_slice_buffer_init(&tcp->write_slices);
   gpr_ref_init(&tcp->refcount, 1);
+  tcp->peer_string = gpr_strdup(peer_string);
   return &tcp->base;
 }
 
diff --git a/src/core/iomgr/tcp_windows.h b/src/core/iomgr/tcp_windows.h
index 4cbc12c53a..7e301db250 100644
--- a/src/core/iomgr/tcp_windows.h
+++ b/src/core/iomgr/tcp_windows.h
@@ -50,7 +50,7 @@
 /* Create a tcp endpoint given a winsock handle.
  * Takes ownership of the handle.
  */
-grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket);
+grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket, char *peer_string);
 
 int grpc_tcp_prepare_socket(SOCKET sock);
 
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index 9e49a807f1..e2d1b6fce9 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -77,10 +77,8 @@ typedef struct {
 
 static void bubble_up_error(grpc_call_element *elem, const char *error_msg) {
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  grpc_transport_stream_op_add_cancellation(
-      &calld->op, GRPC_STATUS_UNAUTHENTICATED,
-      grpc_mdstr_from_string(chand->md_ctx, error_msg));
+  grpc_transport_stream_op_add_cancellation(&calld->op,
+                                            GRPC_STATUS_UNAUTHENTICATED);
   grpc_call_next_op(elem, &calld->op);
 }
 
@@ -316,10 +314,10 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
       (grpc_channel_security_connector *)GRPC_SECURITY_CONNECTOR_REF(
           sc, "client_auth_filter");
   chand->md_ctx = metadata_context;
-  chand->authority_string = grpc_mdstr_from_string(chand->md_ctx, ":authority");
-  chand->path_string = grpc_mdstr_from_string(chand->md_ctx, ":path");
-  chand->error_msg_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-message");
-  chand->status_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-status");
+  chand->authority_string = grpc_mdstr_from_string(chand->md_ctx, ":authority", 0);
+  chand->path_string = grpc_mdstr_from_string(chand->md_ctx, ":path", 0);
+  chand->error_msg_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-message", 0);
+  chand->status_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-status", 0);
 }
 
 /* Destructor for channel data */
@@ -344,6 +342,8 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_client_auth_filter = {
-    auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,       destroy_channel_elem, "client-auth"};
+    auth_start_transport_op, grpc_channel_next_op,
+    sizeof(call_data),       init_call_elem,
+    destroy_call_elem,       sizeof(channel_data),
+    init_channel_elem,       destroy_channel_elem,
+    grpc_call_next_get_peer, "client-auth"};
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index eb178ececb..2239f57378 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -265,8 +265,10 @@ static void ssl_build_config(const char *pem_root_certs,
 
 static void ssl_build_server_config(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs, grpc_ssl_server_config *config) {
+    size_t num_key_cert_pairs, int force_client_auth,
+    grpc_ssl_server_config *config) {
   size_t i;
+  config->force_client_auth = force_client_auth;
   if (pem_root_certs != NULL) {
     ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
                           &config->pem_root_certs_size);
@@ -308,20 +310,20 @@ grpc_credentials *grpc_ssl_credentials_create(
 
 grpc_server_credentials *grpc_ssl_server_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs) {
+    size_t num_key_cert_pairs, int force_client_auth) {
   grpc_ssl_server_credentials *c =
       gpr_malloc(sizeof(grpc_ssl_server_credentials));
   memset(c, 0, sizeof(grpc_ssl_server_credentials));
   c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
   c->base.vtable = &ssl_server_vtable;
   ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
-                          num_key_cert_pairs, &c->config);
+                          num_key_cert_pairs, force_client_auth, &c->config);
   return &c->base;
 }
 
 /* -- Jwt credentials -- */
 
-static void jwt_reset_cache(grpc_jwt_credentials *c) {
+static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
   if (c->cached.jwt_md != NULL) {
     grpc_credentials_md_store_unref(c->cached.jwt_md);
     c->cached.jwt_md = NULL;
@@ -330,11 +332,12 @@ static void jwt_reset_cache(grpc_jwt_credentials *c) {
     gpr_free(c->cached.service_url);
     c->cached.service_url = NULL;
   }
-  c->cached.jwt_expiration = gpr_inf_past;
+  c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
 }
 
 static void jwt_destroy(grpc_credentials *creds) {
-  grpc_jwt_credentials *c = (grpc_jwt_credentials *)creds;
+  grpc_service_account_jwt_access_credentials *c =
+      (grpc_service_account_jwt_access_credentials *)creds;
   grpc_auth_json_key_destruct(&c->key);
   jwt_reset_cache(c);
   gpr_mu_destroy(&c->cache_mu);
@@ -352,9 +355,10 @@ static void jwt_get_request_metadata(grpc_credentials *creds,
                                      const char *service_url,
                                      grpc_credentials_metadata_cb cb,
                                      void *user_data) {
-  grpc_jwt_credentials *c = (grpc_jwt_credentials *)creds;
-  gpr_timespec refresh_threshold = {GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS,
-                                    0};
+  grpc_service_account_jwt_access_credentials *c =
+      (grpc_service_account_jwt_access_credentials *)creds;
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
 
   /* See if we can return a cached jwt. */
   grpc_credentials_md_store *jwt_md = NULL;
@@ -405,15 +409,16 @@ static grpc_credentials_vtable jwt_vtable = {
     jwt_destroy, jwt_has_request_metadata, jwt_has_request_metadata_only,
     jwt_get_request_metadata, NULL};
 
-grpc_credentials *grpc_jwt_credentials_create_from_auth_json_key(
+grpc_credentials *
+grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime) {
-  grpc_jwt_credentials *c;
+  grpc_service_account_jwt_access_credentials *c;
   if (!grpc_auth_json_key_is_valid(&key)) {
     gpr_log(GPR_ERROR, "Invalid input for jwt credentials creation");
     return NULL;
   }
-  c = gpr_malloc(sizeof(grpc_jwt_credentials));
-  memset(c, 0, sizeof(grpc_jwt_credentials));
+  c = gpr_malloc(sizeof(grpc_service_account_jwt_access_credentials));
+  memset(c, 0, sizeof(grpc_service_account_jwt_access_credentials));
   c->base.type = GRPC_CREDENTIALS_TYPE_JWT;
   gpr_ref_init(&c->base.refcount, 1);
   c->base.vtable = &jwt_vtable;
@@ -424,9 +429,9 @@ grpc_credentials *grpc_jwt_credentials_create_from_auth_json_key(
   return &c->base;
 }
 
-grpc_credentials *grpc_jwt_credentials_create(const char *json_key,
-                                              gpr_timespec token_lifetime) {
-  return grpc_jwt_credentials_create_from_auth_json_key(
+grpc_credentials *grpc_service_account_jwt_access_credentials_create(
+    const char *json_key, gpr_timespec token_lifetime) {
+  return grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
       grpc_auth_json_key_create_from_string(json_key), token_lifetime);
 }
 
@@ -522,6 +527,7 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
                  access_token->value);
     token_lifetime->tv_sec = strtol(expires_in->value, NULL, 10);
     token_lifetime->tv_nsec = 0;
+    token_lifetime->clock_type = GPR_TIMESPAN;
     if (*token_md != NULL) grpc_credentials_md_store_unref(*token_md);
     *token_md = grpc_credentials_md_store_create(1);
     grpc_credentials_md_store_add_cstrings(
@@ -558,7 +564,7 @@ static void on_oauth2_token_fetcher_http_response(
     r->cb(r->user_data, c->access_token_md->entries,
           c->access_token_md->num_entries, status);
   } else {
-    c->token_expiration = gpr_inf_past;
+    c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
     r->cb(r->user_data, NULL, 0, status);
   }
   gpr_mu_unlock(&c->mu);
@@ -570,8 +576,8 @@ static void oauth2_token_fetcher_get_request_metadata(
     grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
-  gpr_timespec refresh_threshold = {GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS,
-                                    0};
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
   grpc_credentials_md_store *cached_access_token_md = NULL;
   {
     gpr_mu_lock(&c->mu);
@@ -602,7 +608,7 @@ static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
   c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
   gpr_ref_init(&c->base.refcount, 1);
   gpr_mu_init(&c->mu);
-  c->token_expiration = gpr_inf_past;
+  c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
   c->fetch_func = fetch_func;
   grpc_httpcli_context_init(&c->httpcli_context);
 }
diff --git a/src/core/security/credentials.h b/src/core/security/credentials.h
index cee04b2120..04736525dc 100644
--- a/src/core/security/credentials.h
+++ b/src/core/security/credentials.h
@@ -52,6 +52,8 @@ typedef enum {
   GRPC_CREDENTIALS_ERROR
 } grpc_credentials_status;
 
+#define GRPC_FAKE_TRANSPORT_SECURITY_TYPE "fake"
+
 #define GRPC_CREDENTIALS_TYPE_SSL "Ssl"
 #define GRPC_CREDENTIALS_TYPE_OAUTH2 "Oauth2"
 #define GRPC_CREDENTIALS_TYPE_JWT "Jwt"
@@ -112,6 +114,12 @@ void grpc_credentials_md_store_unref(grpc_credentials_md_store *store);
 
 /* --- grpc_credentials. --- */
 
+/* Creates a fake transport security credentials object for testing. */
+grpc_credentials *grpc_fake_transport_security_credentials_create(void);
+/* Creates a fake server transport security credentials object for testing. */
+grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
+    void);
+
 /* It is the caller's responsibility to gpr_free the result if not NULL. */
 char *grpc_get_well_known_google_credentials_file_path(void);
 
@@ -189,7 +197,8 @@ grpc_credentials *grpc_md_only_test_credentials_create(
 
 /* Private constructor for jwt credentials from an already parsed json key.
    Takes ownership of the key. */
-grpc_credentials *grpc_jwt_credentials_create_from_auth_json_key(
+grpc_credentials *
+grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime);
 
 /* Private constructor for refresh token credentials from an already parsed
@@ -242,7 +251,7 @@ typedef struct {
 
   grpc_auth_json_key key;
   gpr_timespec jwt_lifetime;
-} grpc_jwt_credentials;
+} grpc_service_account_jwt_access_credentials;
 
 /* -- Oauth2TokenFetcher credentials --
 
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index f622deff42..de1929fe76 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -91,7 +91,7 @@ static int is_stack_running_on_compute_engine(void) {
 
   /* The http call is local. If it takes more than one sec, it is for sure not
      on compute engine. */
-  gpr_timespec max_detection_delay = {1, 0};
+  gpr_timespec max_detection_delay = gpr_time_from_seconds(1, GPR_TIMESPAN);
 
   grpc_pollset_init(&detector.pollset);
   detector.is_done = 0;
@@ -112,7 +112,7 @@ static int is_stack_running_on_compute_engine(void) {
      called once for the lifetime of the process by the default credentials. */
   gpr_mu_lock(GRPC_POLLSET_MU(&detector.pollset));
   while (!detector.is_done) {
-    grpc_pollset_work(&detector.pollset, gpr_inf_future);
+    grpc_pollset_work(&detector.pollset, gpr_inf_future(GPR_CLOCK_REALTIME));
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&detector.pollset));
 
@@ -140,8 +140,9 @@ static grpc_credentials *create_default_creds_from_path(char *creds_path) {
   /* First, try an auth json key. */
   key = grpc_auth_json_key_create_from_json(json);
   if (grpc_auth_json_key_is_valid(&key)) {
-    result = grpc_jwt_credentials_create_from_auth_json_key(
-        key, grpc_max_auth_token_lifetime);
+    result =
+        grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
+            key, grpc_max_auth_token_lifetime);
     goto end;
   }
 
diff --git a/src/core/security/json_token.c b/src/core/security/json_token.c
index 9b1ea255ae..021912f333 100644
--- a/src/core/security/json_token.c
+++ b/src/core/security/json_token.c
@@ -49,7 +49,7 @@
 /* --- Constants. --- */
 
 /* 1 hour max. */
-const gpr_timespec grpc_max_auth_token_lifetime = {3600, 0};
+const gpr_timespec grpc_max_auth_token_lifetime = {3600, 0, GPR_TIMESPAN};
 
 #define GRPC_JWT_RSA_SHA256_ALGORITHM "RS256"
 #define GRPC_JWT_TYPE "JWT"
diff --git a/src/core/security/jwt_verifier.c b/src/core/security/jwt_verifier.c
index 9140eb2ef7..1276693da7 100644
--- a/src/core/security/jwt_verifier.c
+++ b/src/core/security/jwt_verifier.c
@@ -109,7 +109,7 @@ static const char *validate_string_field(const grpc_json *json,
 
 static gpr_timespec validate_time_field(const grpc_json *json,
                                         const char *key) {
-  gpr_timespec result = gpr_time_0;
+  gpr_timespec result = gpr_time_0(GPR_CLOCK_REALTIME);
   if (json->type != GRPC_JSON_NUMBER) {
     gpr_log(GPR_ERROR, "Invalid %s field [%s]", key, json->value);
     return result;
@@ -221,17 +221,17 @@ const char *grpc_jwt_claims_audience(const grpc_jwt_claims *claims) {
 }
 
 gpr_timespec grpc_jwt_claims_issued_at(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_past;
+  if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
   return claims->iat;
 }
 
 gpr_timespec grpc_jwt_claims_expires_at(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_future;
+  if (claims == NULL) return gpr_inf_future(GPR_CLOCK_REALTIME);
   return claims->exp;
 }
 
 gpr_timespec grpc_jwt_claims_not_before(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_past;
+  if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
   return claims->nbf;
 }
 
@@ -242,9 +242,9 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer) {
   memset(claims, 0, sizeof(grpc_jwt_claims));
   claims->json = json;
   claims->buffer = buffer;
-  claims->iat = gpr_inf_past;
-  claims->nbf = gpr_inf_past;
-  claims->exp = gpr_inf_future;
+  claims->iat = gpr_inf_past(GPR_CLOCK_REALTIME);
+  claims->nbf = gpr_inf_past(GPR_CLOCK_REALTIME);
+  claims->exp = gpr_inf_future(GPR_CLOCK_REALTIME);
 
   /* Per the spec, all fields are optional. */
   for (cur = json->child; cur != NULL; cur = cur->next) {
@@ -262,13 +262,16 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer) {
       if (claims->jti == NULL) goto error;
     } else if (strcmp(cur->key, "iat") == 0) {
       claims->iat = validate_time_field(cur, "iat");
-      if (gpr_time_cmp(claims->iat, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->iat, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     } else if (strcmp(cur->key, "exp") == 0) {
       claims->exp = validate_time_field(cur, "exp");
-      if (gpr_time_cmp(claims->exp, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->exp, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     } else if (strcmp(cur->key, "nbf") == 0) {
       claims->nbf = validate_time_field(cur, "nbf");
-      if (gpr_time_cmp(claims->nbf, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->nbf, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     }
   }
   return claims;
@@ -359,10 +362,10 @@ void verifier_cb_ctx_destroy(verifier_cb_ctx *ctx) {
 /* --- grpc_jwt_verifier object. --- */
 
 /* Clock skew defaults to one minute. */
-gpr_timespec grpc_jwt_verifier_clock_skew = {60, 0};
+gpr_timespec grpc_jwt_verifier_clock_skew = {60, 0, GPR_TIMESPAN};
 
 /* Max delay defaults to one minute. */
-gpr_timespec grpc_jwt_verifier_max_delay = {60, 0};
+gpr_timespec grpc_jwt_verifier_max_delay = {60, 0, GPR_TIMESPAN};
 
 typedef struct {
   char *email_domain;
diff --git a/src/core/security/secure_endpoint.c b/src/core/security/secure_endpoint.c
index 3548198046..95fbf71f3d 100644
--- a/src/core/security/secure_endpoint.c
+++ b/src/core/security/secure_endpoint.c
@@ -331,9 +331,22 @@ static void endpoint_add_to_pollset(grpc_endpoint *secure_ep,
   grpc_endpoint_add_to_pollset(ep->wrapped_ep, pollset);
 }
 
+static void endpoint_add_to_pollset_set(grpc_endpoint *secure_ep,
+                                    grpc_pollset_set *pollset_set) {
+  secure_endpoint *ep = (secure_endpoint *)secure_ep;
+  grpc_endpoint_add_to_pollset_set(ep->wrapped_ep, pollset_set);
+}
+
+static char *endpoint_get_peer(grpc_endpoint *secure_ep) {
+  secure_endpoint *ep = (secure_endpoint *)secure_ep;
+  return grpc_endpoint_get_peer(ep->wrapped_ep);
+}
+
 static const grpc_endpoint_vtable vtable = {
-    endpoint_notify_on_read, endpoint_write, endpoint_add_to_pollset,
-    endpoint_shutdown, endpoint_unref};
+    endpoint_notify_on_read, endpoint_write,
+    endpoint_add_to_pollset, endpoint_add_to_pollset_set,
+    endpoint_shutdown,       endpoint_unref,
+    endpoint_get_peer};
 
 grpc_endpoint *grpc_secure_endpoint_create(
     struct tsi_frame_protector *protector, grpc_endpoint *transport,
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index 8aee8f3ef4..a354536dcd 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -657,9 +657,10 @@ grpc_security_status grpc_ssl_server_security_connector_create(
       config->pem_private_keys_sizes,
       (const unsigned char **)config->pem_cert_chains,
       config->pem_cert_chains_sizes, config->num_key_cert_pairs,
-      config->pem_root_certs, config->pem_root_certs_size, ssl_cipher_suites(),
-      alpn_protocol_strings, alpn_protocol_string_lengths,
-      (uint16_t)num_alpn_protocols, &c->handshaker_factory);
+      config->pem_root_certs, config->pem_root_certs_size,
+      config->force_client_auth, ssl_cipher_suites(), alpn_protocol_strings,
+      alpn_protocol_string_lengths, (uint16_t)num_alpn_protocols,
+      &c->handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
diff --git a/src/core/security/security_connector.h b/src/core/security/security_connector.h
index a4c723f026..2c9aa1c5a4 100644
--- a/src/core/security/security_connector.h
+++ b/src/core/security/security_connector.h
@@ -201,6 +201,7 @@ typedef struct {
   size_t num_key_cert_pairs;
   unsigned char *pem_root_certs;
   size_t pem_root_certs_size;
+  int force_client_auth;
 } grpc_ssl_server_config;
 
 /* Creates an SSL server_security_connector.
diff --git a/src/core/security/server_auth_filter.c b/src/core/security/server_auth_filter.c
index cc26055440..41d3110001 100644
--- a/src/core/security/server_auth_filter.c
+++ b/src/core/security/server_auth_filter.c
@@ -111,7 +111,6 @@ static void on_md_processing_done(void *user_data,
                                   grpc_auth_context *result) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
 
   if (success) {
     calld->consumed_md = consumed_md;
@@ -125,10 +124,11 @@ static void on_md_processing_done(void *user_data,
         GRPC_AUTH_CONTEXT_REF(result, "refing new context.");
     calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
   } else {
-    grpc_transport_stream_op_add_cancellation(
-        &calld->transport_op, GRPC_STATUS_UNAUTHENTICATED,
-        grpc_mdstr_from_string(chand->mdctx,
-                               "Authentication metadata processing failed."));
+    gpr_slice message = gpr_slice_from_copied_string(
+        "Authentication metadata processing failed.");
+    grpc_sopb_reset(calld->recv_ops);
+    grpc_transport_stream_op_add_close(&calld->transport_op,
+                                       GRPC_STATUS_UNAUTHENTICATED, &message);
     grpc_call_next_op(elem, &calld->transport_op);
   }
 }
@@ -262,6 +262,8 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_server_auth_filter = {
-    auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,       destroy_channel_elem, "server-auth"};
+    auth_start_transport_op, grpc_channel_next_op,
+    sizeof(call_data),       init_call_elem,
+    destroy_call_elem,       sizeof(channel_data),
+    init_channel_elem,       destroy_channel_elem,
+    grpc_call_next_get_peer, "server-auth"};
diff --git a/src/core/support/cancellable.c b/src/core/support/cancellable.c
index 3cbb318ab6..4756f1e125 100644
--- a/src/core/support/cancellable.c
+++ b/src/core/support/cancellable.c
@@ -121,8 +121,9 @@ void gpr_cancellable_cancel(gpr_cancellable *c) {
         } else {
           gpr_event ev;
           gpr_event_init(&ev);
-          gpr_event_wait(&ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                                           gpr_time_from_micros(1000)));
+          gpr_event_wait(
+              &ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                gpr_time_from_micros(1000, GPR_TIMESPAN)));
         }
       }
     } while (failures != 0);
diff --git a/src/core/support/host_port.c b/src/core/support/host_port.c
index 0906ebc2a3..a28f04df9c 100644
--- a/src/core/support/host_port.c
+++ b/src/core/support/host_port.c
@@ -50,7 +50,7 @@ int gpr_join_host_port(char **out, const char *host, int port) {
   }
 }
 
-void gpr_split_host_port(const char *name, char **host, char **port) {
+int gpr_split_host_port(const char *name, char **host, char **port) {
   const char *host_start;
   size_t host_len;
   const char *port_start;
@@ -63,7 +63,7 @@ void gpr_split_host_port(const char *name, char **host, char **port) {
     const char *rbracket = strchr(name, ']');
     if (rbracket == NULL) {
       /* Unmatched [ */
-      return;
+      return 0;
     }
     if (rbracket[1] == '\0') {
       /* ]<end> */
@@ -73,14 +73,14 @@ void gpr_split_host_port(const char *name, char **host, char **port) {
       port_start = rbracket + 2;
     } else {
       /* ]<invalid> */
-      return;
+      return 0;
     }
     host_start = name + 1;
     host_len = (size_t)(rbracket - host_start);
     if (memchr(host_start, ':', host_len) == NULL) {
       /* Require all bracketed hosts to contain a colon, because a hostname or
       IPv4 address should never use brackets. */
-      return;
+      return 0;
     }
   } else {
     const char *colon = strchr(name, ':');
@@ -105,4 +105,6 @@ void gpr_split_host_port(const char *name, char **host, char **port) {
   if (port_start != NULL) {
     *port = gpr_strdup(port_start);
   }
+
+  return 1;
 }
diff --git a/src/core/support/stack_lockfree.c b/src/core/support/stack_lockfree.c
index 9497efbfb5..bc741f8c70 100644
--- a/src/core/support/stack_lockfree.c
+++ b/src/core/support/stack_lockfree.c
@@ -65,12 +65,18 @@ typedef union lockfree_node {
 } lockfree_node;
 
 #define ENTRY_ALIGNMENT_BITS 3 /* make sure that entries aligned to 8-bytes */
-#define INVALID_ENTRY_INDEX ((1 << 16) - 1) /* reserve this entry as invalid \
-                                               */
+#define INVALID_ENTRY_INDEX                        \
+  ((1 << 16) - 1) /* reserve this entry as invalid \
+                       */
 
 struct gpr_stack_lockfree {
   lockfree_node *entries;
   lockfree_node head; /* An atomic entry describing curr head */
+
+#ifndef NDEBUG
+  /* Bitmap of pushed entries to check for double-push or pop */
+  gpr_atm pushed[(INVALID_ENTRY_INDEX+1)/(8*sizeof(gpr_atm))];
+#endif
 };
 
 gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) {
@@ -85,6 +91,11 @@ gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) {
   /* Clear out all entries */
   memset(stack->entries, 0, entries * sizeof(stack->entries[0]));
   memset(&stack->head, 0, sizeof(stack->head));
+#ifndef NDEBUG
+  memset(&stack->pushed, 0, sizeof(stack->pushed));
+#endif
+
+  GPR_ASSERT(sizeof(stack->entries->atm) == sizeof(stack->entries->contents));
 
   /* Point the head at reserved dummy entry */
   stack->head.contents.index = INVALID_ENTRY_INDEX;
@@ -96,27 +107,48 @@ void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) {
   gpr_free(stack);
 }
 
-void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
+int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
   lockfree_node head;
   lockfree_node newhead;
+  lockfree_node curent;
+  lockfree_node newent;
 
   /* First fill in the entry's index and aba ctr for new head */
   newhead.contents.index = (gpr_uint16)entry;
   /* Also post-increment the aba_ctr */
-  newhead.contents.aba_ctr = stack->entries[entry].contents.aba_ctr++;
+  curent.atm = gpr_atm_no_barrier_load(&stack->entries[entry].atm);
+  newhead.contents.aba_ctr = ++curent.contents.aba_ctr;
+  gpr_atm_no_barrier_store(&stack->entries[entry].atm, curent.atm);
+
+#ifndef NDEBUG
+  /* Check for double push */
+  {
+    int pushed_index = entry / (8*sizeof(gpr_atm));
+    int pushed_bit = entry % (8*sizeof(gpr_atm));
+    gpr_atm old_val;
+
+    old_val = gpr_atm_no_barrier_fetch_add(&stack->pushed[pushed_index],
+					   (gpr_atm)(1UL << pushed_bit));
+    GPR_ASSERT((old_val & (1UL<<pushed_bit)) == 0);
+  }
+#endif
 
   do {
     /* Atomically get the existing head value for use */
     head.atm = gpr_atm_no_barrier_load(&(stack->head.atm));
     /* Point to it */
-    stack->entries[entry].contents.index = head.contents.index;
+    newent.atm = gpr_atm_no_barrier_load(&stack->entries[entry].atm);
+    newent.contents.index = head.contents.index;
+    gpr_atm_no_barrier_store(&stack->entries[entry].atm, newent.atm);
   } while (!gpr_atm_rel_cas(&(stack->head.atm), head.atm, newhead.atm));
   /* Use rel_cas above to make sure that entry index is set properly */
+  return head.contents.index == INVALID_ENTRY_INDEX;
 }
 
 int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) {
   lockfree_node head;
   lockfree_node newhead;
+
   do {
     head.atm = gpr_atm_acq_load(&(stack->head.atm));
     if (head.contents.index == INVALID_ENTRY_INDEX) {
@@ -126,5 +158,18 @@ int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) {
         gpr_atm_no_barrier_load(&(stack->entries[head.contents.index].atm));
 
   } while (!gpr_atm_no_barrier_cas(&(stack->head.atm), head.atm, newhead.atm));
+#ifndef NDEBUG
+  /* Check for valid pop */
+  {
+    int pushed_index = head.contents.index / (8*sizeof(gpr_atm));
+    int pushed_bit = head.contents.index % (8*sizeof(gpr_atm));
+    gpr_atm old_val;
+
+    old_val = gpr_atm_no_barrier_fetch_add(&stack->pushed[pushed_index],
+					   -(gpr_atm)(1UL << pushed_bit));
+    GPR_ASSERT((old_val & (1UL<<pushed_bit)) != 0);
+  }
+#endif
+
   return head.contents.index;
 }
diff --git a/src/core/support/stack_lockfree.h b/src/core/support/stack_lockfree.h
index 0bcf73635d..eec960fbb0 100644
--- a/src/core/support/stack_lockfree.h
+++ b/src/core/support/stack_lockfree.h
@@ -42,7 +42,8 @@ gpr_stack_lockfree* gpr_stack_lockfree_create(int entries);
 void gpr_stack_lockfree_destroy(gpr_stack_lockfree* stack);
 
 /* Pass in a valid entry number for the next stack entry */
-void gpr_stack_lockfree_push(gpr_stack_lockfree* stack, int entry);
+/* Returns 1 if this is the first element on the stack, 0 otherwise */
+int gpr_stack_lockfree_push(gpr_stack_lockfree*, int entry);
 
 /* Returns -1 on empty or the actual entry number */
 int gpr_stack_lockfree_pop(gpr_stack_lockfree* stack);
diff --git a/src/core/support/string.c b/src/core/support/string.c
index 09598da946..9babbd910a 100644
--- a/src/core/support/string.c
+++ b/src/core/support/string.c
@@ -38,6 +38,7 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
 #include <grpc/support/port_platform.h>
 #include <grpc/support/useful.h>
 
@@ -174,6 +175,12 @@ int gpr_ltoa(long value, char *string) {
 }
 
 char *gpr_strjoin(const char **strs, size_t nstrs, size_t *final_length) {
+  return gpr_strjoin_sep(strs, nstrs, "", final_length);
+}
+
+char *gpr_strjoin_sep(const char **strs, size_t nstrs, const char *sep,
+                      size_t *final_length) {
+  const size_t sep_len = strlen(sep);
   size_t out_length = 0;
   size_t i;
   char *out;
@@ -181,10 +188,17 @@ char *gpr_strjoin(const char **strs, size_t nstrs, size_t *final_length) {
     out_length += strlen(strs[i]);
   }
   out_length += 1;  /* null terminator */
+  if (nstrs > 0) {
+    out_length += sep_len * (nstrs - 1);  /* separators */
+  }
   out = gpr_malloc(out_length);
   out_length = 0;
   for (i = 0; i < nstrs; i++) {
-    size_t slen = strlen(strs[i]);
+    const size_t slen = strlen(strs[i]);
+    if (i != 0) {
+      memcpy(out + out_length, sep, sep_len);
+      out_length += sep_len;
+    }
     memcpy(out + out_length, strs[i], slen);
     out_length += slen;
   }
@@ -195,6 +209,52 @@ char *gpr_strjoin(const char **strs, size_t nstrs, size_t *final_length) {
   return out;
 }
 
+/** Finds the initial (\a begin) and final (\a end) offsets of the next
+ * substring from \a str + \a read_offset until the next \a sep or the end of \a
+ * str.
+ *
+ * Returns 1 and updates \a begin and \a end. Returns 0 otherwise. */
+static int slice_find_separator_offset(const gpr_slice str,
+                                       const char *sep,
+                                       const size_t read_offset,
+                                       size_t *begin,
+                                       size_t *end) {
+  size_t i;
+  const gpr_uint8 *str_ptr = GPR_SLICE_START_PTR(str) + read_offset;
+  const size_t str_len = GPR_SLICE_LENGTH(str) - read_offset;
+  const size_t sep_len = strlen(sep);
+  if (str_len < sep_len) {
+    return 0;
+  }
+
+  for (i = 0; i <= str_len - sep_len; i++) {
+    if (memcmp(str_ptr + i, sep, sep_len) == 0) {
+      *begin = read_offset;
+      *end = read_offset + i;
+      return 1;
+    }
+  }
+  return 0;
+}
+
+void gpr_slice_split(gpr_slice str, const char *sep, gpr_slice_buffer *dst) {
+  const size_t sep_len = strlen(sep);
+  size_t begin, end;
+
+  GPR_ASSERT(sep_len > 0);
+
+  if (slice_find_separator_offset(str, sep, 0, &begin, &end) != 0) {
+    do {
+      gpr_slice_buffer_add_indexed(dst, gpr_slice_sub(str, begin, end));
+    } while (slice_find_separator_offset(str, sep, end + sep_len, &begin,
+                                         &end) != 0);
+    gpr_slice_buffer_add_indexed(
+        dst, gpr_slice_sub(str, end + sep_len, GPR_SLICE_LENGTH(str)));
+  } else { /* no sep found, add whole input */
+    gpr_slice_buffer_add_indexed(dst, gpr_slice_ref(str));
+  }
+}
+
 void gpr_strvec_init(gpr_strvec *sv) {
   memset(sv, 0, sizeof(*sv));
 }
diff --git a/src/core/support/string.h b/src/core/support/string.h
index d950d908d6..3ac4abeef8 100644
--- a/src/core/support/string.h
+++ b/src/core/support/string.h
@@ -37,6 +37,7 @@
 #include <stddef.h>
 
 #include <grpc/support/port_platform.h>
+#include <grpc/support/slice_buffer.h>
 #include <grpc/support/slice.h>
 
 #ifdef __cplusplus
@@ -77,6 +78,16 @@ void gpr_reverse_bytes(char *str, int len);
    if it is non-null. */
 char *gpr_strjoin(const char **strs, size_t nstrs, size_t *total_length);
 
+/* Join a set of strings using a separator, returning the resulting string.
+   Total combined length (excluding null terminator) is returned in total_length
+   if it is non-null. */
+char *gpr_strjoin_sep(const char **strs, size_t nstrs, const char *sep,
+                      size_t *total_length);
+
+/** Split \a str by the separator \a sep. Results are stored in \a dst, which
+ * should be a properly initialized instance. */
+void gpr_slice_split(gpr_slice str, const char *sep, gpr_slice_buffer *dst);
+
 /* A vector of strings... for building up a final string one piece at a time */
 typedef struct {
   char **strs;
diff --git a/src/core/support/sync_posix.c b/src/core/support/sync_posix.c
index 0ccbd4923f..61572b9a8e 100644
--- a/src/core/support/sync_posix.c
+++ b/src/core/support/sync_posix.c
@@ -63,10 +63,11 @@ void gpr_cv_destroy(gpr_cv *cv) { GPR_ASSERT(pthread_cond_destroy(cv) == 0); }
 
 int gpr_cv_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline) {
   int err = 0;
-  if (gpr_time_cmp(abs_deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(abs_deadline, gpr_inf_future(abs_deadline.clock_type)) == 0) {
     err = pthread_cond_wait(cv, mu);
   } else {
     struct timespec abs_deadline_ts;
+    abs_deadline = gpr_convert_clock_type(abs_deadline, GPR_CLOCK_REALTIME);
     abs_deadline_ts.tv_sec = abs_deadline.tv_sec;
     abs_deadline_ts.tv_nsec = abs_deadline.tv_nsec;
     err = pthread_cond_timedwait(cv, mu, &abs_deadline_ts);
diff --git a/src/core/support/sync_win32.c b/src/core/support/sync_win32.c
index 29b77fc4c2..54f84a46ac 100644
--- a/src/core/support/sync_win32.c
+++ b/src/core/support/sync_win32.c
@@ -83,10 +83,10 @@ int gpr_cv_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline) {
   int timeout = 0;
   DWORD timeout_max_ms;
   mu->locked = 0;
-  if (gpr_time_cmp(abs_deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(abs_deadline, gpr_inf_future(abs_deadline.clock_type)) == 0) {
     SleepConditionVariableCS(cv, &mu->cs, INFINITE);
   } else {
-    gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
+    gpr_timespec now = gpr_now(abs_deadline.clock_type);
     gpr_int64 now_ms = now.tv_sec * 1000 + now.tv_nsec / 1000000;
     gpr_int64 deadline_ms =
         abs_deadline.tv_sec * 1000 + abs_deadline.tv_nsec / 1000000;
diff --git a/src/core/support/time.c b/src/core/support/time.c
index d47b08b266..b523ae01cc 100644
--- a/src/core/support/time.c
+++ b/src/core/support/time.c
@@ -41,6 +41,7 @@
 
 int gpr_time_cmp(gpr_timespec a, gpr_timespec b) {
   int cmp = (a.tv_sec > b.tv_sec) - (a.tv_sec < b.tv_sec);
+  GPR_ASSERT(a.clock_type == b.clock_type);
   if (cmp == 0) {
     cmp = (a.tv_nsec > b.tv_nsec) - (a.tv_nsec < b.tv_nsec);
   }
@@ -71,19 +72,40 @@ gpr_timespec gpr_time_max(gpr_timespec a, gpr_timespec b) {
   ((t)(TYPE_IS_SIGNED(t) ? (TOP_BIT_OF_TYPE(t) - 1) \
                          : ((TOP_BIT_OF_TYPE(t) - 1) << 1) + 1))
 
-const gpr_timespec gpr_time_0 = {0, 0};
-const gpr_timespec gpr_inf_future = {TYPE_MAX(time_t), 0};
-const gpr_timespec gpr_inf_past = {TYPE_MIN(time_t), 0};
+gpr_timespec gpr_time_0(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = 0;
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
+
+gpr_timespec gpr_inf_future(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = TYPE_MAX(time_t);
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
+
+gpr_timespec gpr_inf_past(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = TYPE_MIN(time_t);
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
 
 /* TODO(ctiller): consider merging _nanos, _micros, _millis into a single
    function for maintainability. Similarly for _seconds, _minutes, and _hours */
 
-gpr_timespec gpr_time_from_nanos(long ns) {
+gpr_timespec gpr_time_from_nanos(long ns, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (ns == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (ns == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (ns >= 0) {
     result.tv_sec = ns / GPR_NS_PER_SEC;
     result.tv_nsec = (int)(ns - result.tv_sec * GPR_NS_PER_SEC);
@@ -95,12 +117,13 @@ gpr_timespec gpr_time_from_nanos(long ns) {
   return result;
 }
 
-gpr_timespec gpr_time_from_micros(long us) {
+gpr_timespec gpr_time_from_micros(long us, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (us == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (us == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (us >= 0) {
     result.tv_sec = us / 1000000;
     result.tv_nsec = (int)((us - result.tv_sec * 1000000) * 1000);
@@ -112,12 +135,13 @@ gpr_timespec gpr_time_from_micros(long us) {
   return result;
 }
 
-gpr_timespec gpr_time_from_millis(long ms) {
+gpr_timespec gpr_time_from_millis(long ms, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (ms == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (ms == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (ms >= 0) {
     result.tv_sec = ms / 1000;
     result.tv_nsec = (int)((ms - result.tv_sec * 1000) * 1000000);
@@ -129,12 +153,13 @@ gpr_timespec gpr_time_from_millis(long ms) {
   return result;
 }
 
-gpr_timespec gpr_time_from_seconds(long s) {
+gpr_timespec gpr_time_from_seconds(long s, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (s == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (s == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = s;
     result.tv_nsec = 0;
@@ -142,12 +167,13 @@ gpr_timespec gpr_time_from_seconds(long s) {
   return result;
 }
 
-gpr_timespec gpr_time_from_minutes(long m) {
+gpr_timespec gpr_time_from_minutes(long m, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (m >= LONG_MAX / 60) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (m <= LONG_MIN / 60) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = m * 60;
     result.tv_nsec = 0;
@@ -155,12 +181,13 @@ gpr_timespec gpr_time_from_minutes(long m) {
   return result;
 }
 
-gpr_timespec gpr_time_from_hours(long h) {
+gpr_timespec gpr_time_from_hours(long h, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (h >= LONG_MAX / 3600) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (h <= LONG_MIN / 3600) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = h * 3600;
     result.tv_nsec = 0;
@@ -171,6 +198,8 @@ gpr_timespec gpr_time_from_hours(long h) {
 gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
   gpr_timespec sum;
   int inc = 0;
+  GPR_ASSERT(b.clock_type == GPR_TIMESPAN);
+  sum.clock_type = a.clock_type;
   sum.tv_nsec = a.tv_nsec + b.tv_nsec;
   if (sum.tv_nsec >= GPR_NS_PER_SEC) {
     sum.tv_nsec -= GPR_NS_PER_SEC;
@@ -180,14 +209,14 @@ gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
     sum = a;
   } else if (b.tv_sec == TYPE_MAX(time_t) ||
              (b.tv_sec >= 0 && a.tv_sec >= TYPE_MAX(time_t) - b.tv_sec)) {
-    sum = gpr_inf_future;
+    sum = gpr_inf_future(sum.clock_type);
   } else if (b.tv_sec == TYPE_MIN(time_t) ||
              (b.tv_sec <= 0 && a.tv_sec <= TYPE_MIN(time_t) - b.tv_sec)) {
-    sum = gpr_inf_past;
+    sum = gpr_inf_past(sum.clock_type);
   } else {
     sum.tv_sec = a.tv_sec + b.tv_sec;
     if (inc != 0 && sum.tv_sec == TYPE_MAX(time_t) - 1) {
-      sum = gpr_inf_future;
+      sum = gpr_inf_future(sum.clock_type);
     } else {
       sum.tv_sec += inc;
     }
@@ -198,6 +227,12 @@ gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
 gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
   gpr_timespec diff;
   int dec = 0;
+  if (b.clock_type == GPR_TIMESPAN) {
+    diff.clock_type = a.clock_type;
+  } else {
+    GPR_ASSERT(a.clock_type == b.clock_type);
+    diff.clock_type = GPR_TIMESPAN;
+  }
   diff.tv_nsec = a.tv_nsec - b.tv_nsec;
   if (diff.tv_nsec < 0) {
     diff.tv_nsec += GPR_NS_PER_SEC;
@@ -207,14 +242,14 @@ gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
     diff = a;
   } else if (b.tv_sec == TYPE_MIN(time_t) ||
              (b.tv_sec <= 0 && a.tv_sec >= TYPE_MAX(time_t) + b.tv_sec)) {
-    diff = gpr_inf_future;
+    diff = gpr_inf_future(GPR_CLOCK_REALTIME);
   } else if (b.tv_sec == TYPE_MAX(time_t) ||
              (b.tv_sec >= 0 && a.tv_sec <= TYPE_MIN(time_t) + b.tv_sec)) {
-    diff = gpr_inf_past;
+    diff = gpr_inf_past(GPR_CLOCK_REALTIME);
   } else {
     diff.tv_sec = a.tv_sec - b.tv_sec;
     if (dec != 0 && diff.tv_sec == TYPE_MIN(time_t) + 1) {
-      diff = gpr_inf_past;
+      diff = gpr_inf_past(GPR_CLOCK_REALTIME);
     } else {
       diff.tv_sec -= dec;
     }
@@ -225,6 +260,9 @@ gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
 int gpr_time_similar(gpr_timespec a, gpr_timespec b, gpr_timespec threshold) {
   int cmp_ab;
 
+  GPR_ASSERT(a.clock_type == b.clock_type);
+  GPR_ASSERT(threshold.clock_type == GPR_TIMESPAN);
+
   cmp_ab = gpr_time_cmp(a, b);
   if (cmp_ab == 0) return 1;
   if (cmp_ab < 0) {
@@ -252,3 +290,30 @@ gpr_int32 gpr_time_to_millis(gpr_timespec t) {
 double gpr_timespec_to_micros(gpr_timespec t) {
   return (double)t.tv_sec * GPR_US_PER_SEC + t.tv_nsec * 1e-3;
 }
+
+gpr_timespec gpr_convert_clock_type(gpr_timespec t, gpr_clock_type clock_type) {
+  if (t.clock_type == clock_type) {
+    return t;
+  }
+
+  if (t.tv_nsec == 0) {
+    if (t.tv_sec == TYPE_MAX(time_t)) {
+      t.clock_type = clock_type;
+      return t;
+    }
+    if (t.tv_sec == TYPE_MIN(time_t)) {
+      t.clock_type = clock_type;
+      return t;
+    }
+  }
+
+  if (clock_type == GPR_TIMESPAN) {
+    return gpr_time_sub(t, gpr_now(t.clock_type));
+  }
+
+  if (t.clock_type == GPR_TIMESPAN) {
+    return gpr_time_add(gpr_now(clock_type), t);
+  }
+
+  return gpr_time_add(gpr_now(clock_type), gpr_time_sub(t, gpr_now(t.clock_type)));
+}
diff --git a/src/core/support/time_posix.c b/src/core/support/time_posix.c
index f9b7958783..841485c4b4 100644
--- a/src/core/support/time_posix.c
+++ b/src/core/support/time_posix.c
@@ -38,6 +38,7 @@
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
+#include <grpc/support/log.h>
 #include <grpc/support/time.h>
 
 static struct timespec timespec_from_gpr(gpr_timespec gts) {
@@ -48,10 +49,12 @@ static struct timespec timespec_from_gpr(gpr_timespec gts) {
 }
 
 #if _POSIX_TIMERS > 0
-static gpr_timespec gpr_from_timespec(struct timespec ts) {
+static gpr_timespec gpr_from_timespec(struct timespec ts,
+                                      gpr_clock_type clock) {
   gpr_timespec rv;
   rv.tv_sec = ts.tv_sec;
   rv.tv_nsec = (int)ts.tv_nsec;
+  rv.clock_type = clock;
   return rv;
 }
 
@@ -62,8 +65,9 @@ void gpr_time_init(void) {}
 
 gpr_timespec gpr_now(gpr_clock_type clock) {
   struct timespec now;
+  GPR_ASSERT(clock != GPR_TIMESPAN);
   clock_gettime(clockid_for_gpr_clock[clock], &now);
-  return gpr_from_timespec(now);
+  return gpr_from_timespec(now, clock);
 }
 #else
 /* For some reason Apple's OSes haven't implemented clock_gettime. */
@@ -88,6 +92,7 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
   struct timeval now_tv;
   double now_dbl;
 
+  now.clock_type = clock;
   switch (clock) {
     case GPR_CLOCK_REALTIME:
       gettimeofday(&now_tv, NULL);
@@ -99,6 +104,8 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
       now.tv_sec = now_dbl * 1e-9;
       now.tv_nsec = now_dbl - now.tv_sec * 1e9;
       break;
+    case GPR_TIMESPAN:
+      abort();
   }
 
   return now;
@@ -113,7 +120,7 @@ void gpr_sleep_until(gpr_timespec until) {
   for (;;) {
     /* We could simplify by using clock_nanosleep instead, but it might be
      * slightly less portable. */
-    now = gpr_now(GPR_CLOCK_REALTIME);
+    now = gpr_now(until.clock_type);
     if (gpr_time_cmp(until, now) <= 0) {
       return;
     }
diff --git a/src/core/support/time_win32.c b/src/core/support/time_win32.c
index fa77c74eeb..7f64c80e27 100644
--- a/src/core/support/time_win32.c
+++ b/src/core/support/time_win32.c
@@ -55,6 +55,7 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
   struct _timeb now_tb;
   LARGE_INTEGER timestamp;
   double now_dbl;
+  now_tv.clock_type = clock;
   switch (clock) {
     case GPR_CLOCK_REALTIME:
       _ftime_s(&now_tb);
@@ -79,7 +80,7 @@ void gpr_sleep_until(gpr_timespec until) {
   for (;;) {
     /* We could simplify by using clock_nanosleep instead, but it might be
      * slightly less portable. */
-    now = gpr_now(GPR_CLOCK_REALTIME);
+    now = gpr_now(until.clock_type);
     if (gpr_time_cmp(until, now) <= 0) {
       return;
     }
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 71f4235571..327a096ffb 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -30,24 +30,24 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <grpc/compression.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
 
-#include "src/core/census/grpc_context.h"
-#include "src/core/surface/call.h"
 #include "src/core/channel/channel_stack.h"
 #include "src/core/iomgr/alarm.h"
 #include "src/core/profiling/timers.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/byte_buffer_queue.h"
+#include "src/core/surface/call.h"
 #include "src/core/surface/channel.h"
 #include "src/core/surface/completion_queue.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <assert.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 
 /** The maximum number of completions possible.
     Based upon the maximum number of individually queueable ops in the batch
@@ -235,8 +235,8 @@ struct grpc_call {
   /* Received call statuses from various sources */
   received_status status[STATUS_SOURCE_COUNT];
 
-  /* Compression level for the call */
-  grpc_compression_level compression_level;
+  /* Compression algorithm for the call */
+  grpc_compression_algorithm compression_algorithm;
 
   /* Contexts for various subsystems (security, tracing, ...). */
   grpc_call_context_element context[GRPC_CONTEXT_COUNT];
@@ -347,7 +347,8 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
   }
   grpc_call_stack_init(channel_stack, server_transport_data, initial_op_ptr,
                        CALL_STACK_FROM_CALL(call));
-  if (gpr_time_cmp(send_deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(send_deadline, gpr_inf_future(send_deadline.clock_type)) !=
+      0) {
     set_deadline_alarm(call, send_deadline);
   }
   return call;
@@ -469,9 +470,14 @@ static void set_status_code(grpc_call *call, status_source source,
   }
 }
 
-static void set_decode_compression_level(grpc_call *call,
-                                         grpc_compression_level clevel) {
-  call->compression_level = clevel;
+static void set_compression_algorithm(grpc_call *call,
+                                      grpc_compression_algorithm algo) {
+  call->compression_algorithm = algo;
+}
+
+grpc_compression_algorithm grpc_call_get_compression_algorithm(
+    const grpc_call *call) {
+  return call->compression_algorithm;
 }
 
 static void set_status_details(grpc_call *call, status_source source,
@@ -762,8 +768,18 @@ static void call_on_done_send(void *pc, int success) {
 static void finish_message(grpc_call *call) {
   if (call->error_status_set == 0) {
     /* TODO(ctiller): this could be a lot faster if coded directly */
-    grpc_byte_buffer *byte_buffer = grpc_raw_byte_buffer_create(
-        call->incoming_message.slices, call->incoming_message.count);
+    grpc_byte_buffer *byte_buffer;
+    /* some aliases for readability */
+    gpr_slice *slices = call->incoming_message.slices;
+    const size_t nslices = call->incoming_message.count;
+
+    if ((call->incoming_message_flags & GRPC_WRITE_INTERNAL_COMPRESS) &&
+        (call->compression_algorithm > GRPC_COMPRESS_NONE)) {
+      byte_buffer = grpc_raw_compressed_byte_buffer_create(
+          slices, nslices, call->compression_algorithm);
+    } else {
+      byte_buffer = grpc_raw_byte_buffer_create(slices, nslices);
+    }
     grpc_bbq_push(&call->incoming_queue, byte_buffer);
   }
   gpr_slice_buffer_reset_and_unref(&call->incoming_message);
@@ -782,6 +798,25 @@ static int begin_message(grpc_call *call, grpc_begin_message msg) {
     gpr_free(message);
     return 0;
   }
+  /* sanity check: if message flags indicate a compressed message, the
+   * compression level should already be present in the call, as parsed off its
+   * corresponding metadata. */
+  if ((msg.flags & GRPC_WRITE_INTERNAL_COMPRESS) &&
+      (call->compression_algorithm == GRPC_COMPRESS_NONE)) {
+    char *message = NULL;
+    char *alg_name;
+    if (!grpc_compression_algorithm_name(call->compression_algorithm,
+                                         &alg_name)) {
+      /* This shouldn't happen, other than due to data corruption */
+      alg_name = "<unknown>";
+    }
+    gpr_asprintf(&message,
+                 "Invalid compression algorithm (%s) for compressed message.",
+                 alg_name);
+    cancel_with_status(call, GRPC_STATUS_INTERNAL, message);
+    gpr_free(message);
+    return 0;
+  }
   /* stash away parameters, and prepare for incoming slices */
   if (msg.length > grpc_channel_get_max_message_length(call->channel)) {
     char *message = NULL;
@@ -897,7 +932,7 @@ static int prepare_application_metadata(grpc_call *call, size_t count,
     GPR_ASSERT(sizeof(grpc_linked_mdelem) == sizeof(md->internal_data));
     l->md = grpc_mdelem_from_string_and_buffer(call->metadata_context, md->key,
                                                (const gpr_uint8 *)md->value,
-                                               md->value_length);
+                                               md->value_length, 1);
     if (!grpc_mdstr_is_legal_header(l->md->key)) {
       gpr_log(GPR_ERROR, "attempt to send invalid metadata key");
       return 0;
@@ -985,7 +1020,7 @@ static int fill_send_ops(grpc_call *call, grpc_transport_stream_op *op) {
           mdb.list = chain_metadata_from_app(call, data.send_metadata.count,
                                              data.send_metadata.metadata);
           mdb.garbage.head = mdb.garbage.tail = NULL;
-          mdb.deadline = gpr_inf_future;
+          mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
           /* send status */
           /* TODO(ctiller): cache common status values */
           data = call->request_data[GRPC_IOREQ_SEND_STATUS];
@@ -1168,7 +1203,7 @@ grpc_call_error grpc_call_cancel_with_status(grpc_call *c,
 static grpc_call_error cancel_with_status(grpc_call *c, grpc_status_code status,
                                           const char *description) {
   grpc_mdstr *details =
-      description ? grpc_mdstr_from_string(c->metadata_context, description)
+      description ? grpc_mdstr_from_string(c->metadata_context, description, 0)
                   : NULL;
 
   GPR_ASSERT(status != GRPC_STATUS_OK);
@@ -1218,6 +1253,11 @@ static void execute_op(grpc_call *call, grpc_transport_stream_op *op) {
   elem->filter->start_transport_stream_op(elem, op);
 }
 
+char *grpc_call_get_peer(grpc_call *call) {
+  grpc_call_element *elem = CALL_ELEM_FROM_CALL(call, 0);
+  return elem->filter->get_peer(elem);
+}
+
 grpc_call *grpc_call_from_top_element(grpc_call_element *elem) {
   return CALL_FROM_TOP_ELEM(elem);
 }
@@ -1243,8 +1283,9 @@ static void set_deadline_alarm(grpc_call *call, gpr_timespec deadline) {
   }
   GRPC_CALL_INTERNAL_REF(call, "alarm");
   call->have_alarm = 1;
-  grpc_alarm_init(&call->alarm, deadline, call_alarm, call,
-                  gpr_now(GPR_CLOCK_REALTIME));
+  grpc_alarm_init(&call->alarm,
+                  gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
+                  call_alarm, call, gpr_now(GPR_CLOCK_MONOTONIC));
 }
 
 /* we offset status by a small amount when storing it into transport metadata
@@ -1276,25 +1317,22 @@ static gpr_uint32 decode_status(grpc_mdelem *md) {
 static void destroy_compression(void *ignored) {}
 
 static gpr_uint32 decode_compression(grpc_mdelem *md) {
-  grpc_compression_level clevel;
-  void *user_data = grpc_mdelem_get_user_data(md, destroy_status);
+  grpc_compression_algorithm algorithm;
+  void *user_data = grpc_mdelem_get_user_data(md, destroy_compression);
   if (user_data) {
-    clevel = ((grpc_compression_level)(gpr_intptr)user_data) - COMPRESS_OFFSET;
+    algorithm =
+        ((grpc_compression_level)(gpr_intptr)user_data) - COMPRESS_OFFSET;
   } else {
-    gpr_uint32 parsed_clevel_bytes;
-    if (gpr_parse_bytes_to_uint32(grpc_mdstr_as_c_string(md->value),
-                                  GPR_SLICE_LENGTH(md->value->slice),
-                                  &parsed_clevel_bytes)) {
-      /* the following cast is safe, as a gpr_uint32 should be able to hold all
-       * possible values of the grpc_compression_level enum */
-      clevel = (grpc_compression_level)parsed_clevel_bytes;
-    } else {
-      clevel = GRPC_COMPRESS_LEVEL_NONE; /* could not parse, no compression */
+    const char *md_c_str = grpc_mdstr_as_c_string(md->value);
+    if (!grpc_compression_algorithm_parse(md_c_str, &algorithm)) {
+      gpr_log(GPR_ERROR, "Invalid compression algorithm: '%s'", md_c_str);
+      assert(0);
     }
-    grpc_mdelem_set_user_data(md, destroy_compression,
-                              (void *)(gpr_intptr)(clevel + COMPRESS_OFFSET));
+    grpc_mdelem_set_user_data(
+        md, destroy_compression,
+        (void *)(gpr_intptr)(algorithm + COMPRESS_OFFSET));
   }
-  return clevel;
+  return algorithm;
 }
 
 static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
@@ -1313,8 +1351,8 @@ static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
     } else if (key == grpc_channel_get_message_string(call->channel)) {
       set_status_details(call, STATUS_FROM_WIRE, GRPC_MDSTR_REF(md->value));
     } else if (key ==
-               grpc_channel_get_compresssion_level_string(call->channel)) {
-      set_decode_compression_level(call, decode_compression(md));
+               grpc_channel_get_compression_algorithm_string(call->channel)) {
+      set_compression_algorithm(call, decode_compression(md));
     } else {
       dest = &call->buffered_metadata[is_trailing];
       if (dest->count == dest->capacity) {
@@ -1338,7 +1376,8 @@ static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
       l->md = 0;
     }
   }
-  if (gpr_time_cmp(md->deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(md->deadline, gpr_inf_future(md->deadline.clock_type)) !=
+      0) {
     set_deadline_alarm(call, md->deadline);
   }
   if (!is_trailing) {
@@ -1429,7 +1468,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
         req = &reqs[out++];
         req->op = GRPC_IOREQ_SEND_MESSAGE;
         req->data.send_message = op->data.send_message;
-        req->flags = ops->flags;
+        req->flags = op->flags;
         break;
       case GRPC_OP_SEND_CLOSE_FROM_CLIENT:
         /* Flag validation: currently allow no flags */
@@ -1461,7 +1500,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
             op->data.send_status_from_server.status_details != NULL
                 ? grpc_mdstr_from_string(
                       call->metadata_context,
-                      op->data.send_status_from_server.status_details)
+                      op->data.send_status_from_server.status_details, 0)
                 : NULL;
         req = &reqs[out++];
         req->op = GRPC_IOREQ_SEND_CLOSE;
diff --git a/src/core/surface/call.h b/src/core/surface/call.h
index 3b6f9c942e..265638d519 100644
--- a/src/core/surface/call.h
+++ b/src/core/surface/call.h
@@ -134,6 +134,10 @@ void grpc_server_log_request_call(char *file, int line,
                                   grpc_completion_queue *cq_for_notification,
                                   void *tag);
 
+void grpc_server_log_shutdown(char *file, int line, gpr_log_severity severity,
+                              grpc_server *server, grpc_completion_queue *cq,
+                              void *tag);
+
 /* Set a context pointer.
    No thread safety guarantees are made wrt this value. */
 void grpc_call_context_set(grpc_call *call, grpc_context_index elem,
@@ -151,6 +155,9 @@ void *grpc_call_context_get(grpc_call *call, grpc_context_index elem);
   grpc_server_log_request_call(sev, server, call, details, initial_metadata, \
                                cq_bound_to_call, cq_for_notifications, tag)
 
+#define GRPC_SERVER_LOG_SHUTDOWN(sev, server, cq, tag) \
+  if (grpc_trace_batch) grpc_server_log_shutdown(sev, server, cq, tag)
+
 gpr_uint8 grpc_call_is_client(grpc_call *call);
 
 #endif /* GRPC_INTERNAL_CORE_SURFACE_CALL_H */
diff --git a/src/core/surface/call_log_batch.c b/src/core/surface/call_log_batch.c
index 997046d954..7bf8cafc24 100644
--- a/src/core/surface/call_log_batch.c
+++ b/src/core/surface/call_log_batch.c
@@ -136,3 +136,11 @@ void grpc_server_log_request_call(char *file, int line,
           "tag=%p)", server, call, details, initial_metadata,
           cq_bound_to_call, cq_for_notification, tag);
 }
+
+void grpc_server_log_shutdown(char *file, int line, gpr_log_severity severity,
+                              grpc_server *server, grpc_completion_queue *cq,
+                              void *tag) {
+  gpr_log(file, line, severity,
+          "grpc_server_shutdown_and_notify(server=%p, cq=%p, tag=%p)", server,
+          cq, tag);
+}
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index b7826d4dfc..81f673f856 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -36,12 +36,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/call.h"
 #include "src/core/surface/init.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
 
 /** Cache grpc-status: X mdelems for X = 0..NUM_CACHED_STATUS_ELEMS.
  *  Avoids needing to take a metadata context lock for sending status
@@ -63,7 +65,7 @@ struct grpc_channel {
   grpc_mdctx *metadata_context;
   /** mdstr for the grpc-status key */
   grpc_mdstr *grpc_status_string;
-  grpc_mdstr *grpc_compression_level_string;
+  grpc_mdstr *grpc_compression_algorithm_string;
   grpc_mdstr *grpc_message_string;
   grpc_mdstr *path_string;
   grpc_mdstr *authority_string;
@@ -73,6 +75,7 @@ struct grpc_channel {
   gpr_mu registered_call_mu;
   registered_call *registered_calls;
   grpc_iomgr_closure destroy_closure;
+  char *target;
 };
 
 #define CHANNEL_STACK_FROM_CHANNEL(c) ((grpc_channel_stack *)((c) + 1))
@@ -85,31 +88,32 @@ struct grpc_channel {
 #define DEFAULT_MAX_MESSAGE_LENGTH (100 * 1024 * 1024)
 
 grpc_channel *grpc_channel_create_from_filters(
-    const grpc_channel_filter **filters, size_t num_filters,
+    const char *target, const grpc_channel_filter **filters, size_t num_filters,
     const grpc_channel_args *args, grpc_mdctx *mdctx, int is_client) {
   size_t i;
   size_t size =
       sizeof(grpc_channel) + grpc_channel_stack_size(filters, num_filters);
   grpc_channel *channel = gpr_malloc(size);
   memset(channel, 0, sizeof(*channel));
+  channel->target = gpr_strdup(target);
   GPR_ASSERT(grpc_is_initialized() && "call grpc_init()");
   channel->is_client = is_client;
   /* decremented by grpc_channel_destroy */
   gpr_ref_init(&channel->refs, 1);
   channel->metadata_context = mdctx;
-  channel->grpc_status_string = grpc_mdstr_from_string(mdctx, "grpc-status");
-  channel->grpc_compression_level_string =
-      grpc_mdstr_from_string(mdctx, "grpc-compression-level");
-  channel->grpc_message_string = grpc_mdstr_from_string(mdctx, "grpc-message");
+  channel->grpc_status_string = grpc_mdstr_from_string(mdctx, "grpc-status", 0);
+  channel->grpc_compression_algorithm_string =
+      grpc_mdstr_from_string(mdctx, "grpc-encoding", 0);
+  channel->grpc_message_string = grpc_mdstr_from_string(mdctx, "grpc-message", 0);
   for (i = 0; i < NUM_CACHED_STATUS_ELEMS; i++) {
     char buf[GPR_LTOA_MIN_BUFSIZE];
     gpr_ltoa(i, buf);
     channel->grpc_status_elem[i] = grpc_mdelem_from_metadata_strings(
         mdctx, GRPC_MDSTR_REF(channel->grpc_status_string),
-        grpc_mdstr_from_string(mdctx, buf));
+        grpc_mdstr_from_string(mdctx, buf, 0));
   }
-  channel->path_string = grpc_mdstr_from_string(mdctx, ":path");
-  channel->authority_string = grpc_mdstr_from_string(mdctx, ":authority");
+  channel->path_string = grpc_mdstr_from_string(mdctx, ":path", 0);
+  channel->authority_string = grpc_mdstr_from_string(mdctx, ":authority", 0);
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = NULL;
 
@@ -137,18 +141,25 @@ grpc_channel *grpc_channel_create_from_filters(
   return channel;
 }
 
+char *grpc_channel_get_target(grpc_channel *channel) {
+  return gpr_strdup(channel->target);
+}
+
 static grpc_call *grpc_channel_create_call_internal(
     grpc_channel *channel, grpc_completion_queue *cq, grpc_mdelem *path_mdelem,
     grpc_mdelem *authority_mdelem, gpr_timespec deadline) {
   grpc_mdelem *send_metadata[2];
+  int num_metadata = 0;
 
   GPR_ASSERT(channel->is_client);
 
-  send_metadata[0] = path_mdelem;
-  send_metadata[1] = authority_mdelem;
+  send_metadata[num_metadata++] = path_mdelem;
+  if (authority_mdelem != NULL) {
+    send_metadata[num_metadata++] = authority_mdelem;
+  }
 
   return grpc_call_create(channel, cq, NULL, send_metadata,
-                          GPR_ARRAY_SIZE(send_metadata), deadline);
+                          num_metadata, deadline);
 }
 
 grpc_call *grpc_channel_create_call(grpc_channel *channel,
@@ -159,10 +170,11 @@ grpc_call *grpc_channel_create_call(grpc_channel *channel,
       channel, cq,
       grpc_mdelem_from_metadata_strings(
           channel->metadata_context, GRPC_MDSTR_REF(channel->path_string),
-          grpc_mdstr_from_string(channel->metadata_context, method)),
+          grpc_mdstr_from_string(channel->metadata_context, method, 0)),
+      host ?
       grpc_mdelem_from_metadata_strings(
           channel->metadata_context, GRPC_MDSTR_REF(channel->authority_string),
-          grpc_mdstr_from_string(channel->metadata_context, host)),
+          grpc_mdstr_from_string(channel->metadata_context, host, 0)) : NULL,
       deadline);
 }
 
@@ -171,10 +183,10 @@ void *grpc_channel_register_call(grpc_channel *channel, const char *method,
   registered_call *rc = gpr_malloc(sizeof(registered_call));
   rc->path = grpc_mdelem_from_metadata_strings(
       channel->metadata_context, GRPC_MDSTR_REF(channel->path_string),
-      grpc_mdstr_from_string(channel->metadata_context, method));
-  rc->authority = grpc_mdelem_from_metadata_strings(
+      grpc_mdstr_from_string(channel->metadata_context, method, 0));
+  rc->authority = host ? grpc_mdelem_from_metadata_strings(
       channel->metadata_context, GRPC_MDSTR_REF(channel->authority_string),
-      grpc_mdstr_from_string(channel->metadata_context, host));
+      grpc_mdstr_from_string(channel->metadata_context, host, 0)) : NULL;
   gpr_mu_lock(&channel->registered_call_mu);
   rc->next = channel->registered_calls;
   channel->registered_calls = rc;
@@ -188,7 +200,7 @@ grpc_call *grpc_channel_create_registered_call(
   registered_call *rc = registered_call_handle;
   return grpc_channel_create_call_internal(
       channel, completion_queue, GRPC_MDELEM_REF(rc->path),
-      GRPC_MDELEM_REF(rc->authority), deadline);
+      rc->authority ? GRPC_MDELEM_REF(rc->authority) : NULL, deadline);
 }
 
 #ifdef GRPC_CHANNEL_REF_COUNT_DEBUG
@@ -209,7 +221,7 @@ static void destroy_channel(void *p, int ok) {
     GRPC_MDELEM_UNREF(channel->grpc_status_elem[i]);
   }
   GRPC_MDSTR_UNREF(channel->grpc_status_string);
-  GRPC_MDSTR_UNREF(channel->grpc_compression_level_string);
+  GRPC_MDSTR_UNREF(channel->grpc_compression_algorithm_string);
   GRPC_MDSTR_UNREF(channel->grpc_message_string);
   GRPC_MDSTR_UNREF(channel->path_string);
   GRPC_MDSTR_UNREF(channel->authority_string);
@@ -222,6 +234,7 @@ static void destroy_channel(void *p, int ok) {
   }
   grpc_mdctx_unref(channel->metadata_context);
   gpr_mu_destroy(&channel->registered_call_mu);
+  gpr_free(channel->target);
   gpr_free(channel);
 }
 
@@ -262,8 +275,9 @@ grpc_mdstr *grpc_channel_get_status_string(grpc_channel *channel) {
   return channel->grpc_status_string;
 }
 
-grpc_mdstr *grpc_channel_get_compresssion_level_string(grpc_channel *channel) {
-  return channel->grpc_compression_level_string;
+grpc_mdstr *grpc_channel_get_compression_algorithm_string(
+    grpc_channel *channel) {
+  return channel->grpc_compression_algorithm_string;
 }
 
 grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel, int i) {
@@ -274,7 +288,7 @@ grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel, int i) {
     gpr_ltoa(i, tmp);
     return grpc_mdelem_from_metadata_strings(
         channel->metadata_context, GRPC_MDSTR_REF(channel->grpc_status_string),
-        grpc_mdstr_from_string(channel->metadata_context, tmp));
+        grpc_mdstr_from_string(channel->metadata_context, tmp, 0));
   }
 }
 
diff --git a/src/core/surface/channel.h b/src/core/surface/channel.h
index 71f8a55731..9e0646efaa 100644
--- a/src/core/surface/channel.h
+++ b/src/core/surface/channel.h
@@ -38,7 +38,7 @@
 #include "src/core/client_config/subchannel_factory.h"
 
 grpc_channel *grpc_channel_create_from_filters(
-    const grpc_channel_filter **filters, size_t count,
+    const char *target, const grpc_channel_filter **filters, size_t count,
     const grpc_channel_args *args, grpc_mdctx *mdctx, int is_client);
 
 /** Get a (borrowed) pointer to this channels underlying channel stack */
@@ -54,7 +54,8 @@ grpc_mdctx *grpc_channel_get_metadata_context(grpc_channel *channel);
 grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel,
                                                  int status_code);
 grpc_mdstr *grpc_channel_get_status_string(grpc_channel *channel);
-grpc_mdstr *grpc_channel_get_compresssion_level_string(grpc_channel *channel);
+grpc_mdstr *grpc_channel_get_compression_algorithm_string(
+    grpc_channel *channel);
 grpc_mdstr *grpc_channel_get_message_string(grpc_channel *channel);
 gpr_uint32 grpc_channel_get_max_message_length(grpc_channel *channel);
 
diff --git a/src/core/surface/channel_connectivity.c b/src/core/surface/channel_connectivity.c
new file mode 100644
index 0000000000..1223706457
--- /dev/null
+++ b/src/core/surface/channel_connectivity.c
@@ -0,0 +1,185 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/surface/channel.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+
+#include "src/core/channel/client_channel.h"
+#include "src/core/iomgr/alarm.h"
+#include "src/core/surface/completion_queue.h"
+
+grpc_connectivity_state grpc_channel_check_connectivity_state(
+    grpc_channel *channel, int try_to_connect) {
+  /* forward through to the underlying client channel */
+  grpc_channel_element *client_channel_elem =
+      grpc_channel_stack_last_element(grpc_channel_get_channel_stack(channel));
+  if (client_channel_elem->filter != &grpc_client_channel_filter) {
+    gpr_log(GPR_ERROR,
+            "grpc_channel_check_connectivity_state called on something that is "
+            "not a client channel, but '%s'",
+            client_channel_elem->filter->name);
+    return GRPC_CHANNEL_FATAL_FAILURE;
+  }
+  return grpc_client_channel_check_connectivity_state(client_channel_elem,
+                                                      try_to_connect);
+}
+
+typedef enum {
+  WAITING,
+  CALLING_BACK,
+  CALLING_BACK_AND_FINISHED,
+  CALLED_BACK
+} callback_phase;
+
+typedef struct {
+  gpr_mu mu;
+  callback_phase phase;
+  int success;
+  grpc_iomgr_closure on_complete;
+  grpc_alarm alarm;
+  grpc_connectivity_state state;
+  grpc_completion_queue *cq;
+  grpc_cq_completion completion_storage;
+  grpc_channel *channel;
+  void *tag;
+} state_watcher;
+
+static void delete_state_watcher(state_watcher *w) {
+  grpc_channel_element *client_channel_elem =
+      grpc_channel_stack_last_element(grpc_channel_get_channel_stack(w->channel));
+  grpc_client_channel_del_interested_party(client_channel_elem, grpc_cq_pollset(w->cq));
+  GRPC_CHANNEL_INTERNAL_UNREF(w->channel, "watch_connectivity");
+  gpr_mu_destroy(&w->mu);
+  gpr_free(w);
+}
+
+static void finished_completion(void *pw, grpc_cq_completion *ignored) {
+  int delete = 0;
+  state_watcher *w = pw;
+  gpr_mu_lock(&w->mu);
+  switch (w->phase) {
+    case WAITING:
+    case CALLED_BACK:
+      gpr_log(GPR_ERROR, "should never reach here");
+      abort();
+      break;
+    case CALLING_BACK:
+      w->phase = CALLED_BACK;
+      break;
+    case CALLING_BACK_AND_FINISHED:
+      delete = 1;
+      break;
+  }
+  gpr_mu_unlock(&w->mu);
+
+  if (delete) {
+    delete_state_watcher(w);
+  }
+}
+
+static void partly_done(state_watcher *w, int due_to_completion) {
+  int delete = 0;
+
+  if (due_to_completion) {
+    gpr_mu_lock(&w->mu);
+    w->success = 1;
+    gpr_mu_unlock(&w->mu);
+    grpc_alarm_cancel(&w->alarm);
+  }
+
+  gpr_mu_lock(&w->mu);
+  switch (w->phase) {
+    case WAITING:
+      w->phase = CALLING_BACK;
+      grpc_cq_end_op(w->cq, w->tag, w->success, finished_completion, w,
+                     &w->completion_storage);
+      break;
+    case CALLING_BACK:
+      w->phase = CALLING_BACK_AND_FINISHED;
+      break;
+    case CALLING_BACK_AND_FINISHED:
+      gpr_log(GPR_ERROR, "should never reach here");
+      abort();
+      break;
+    case CALLED_BACK:
+      delete = 1;
+      break;
+  }
+  gpr_mu_unlock(&w->mu);
+
+  if (delete) {
+    delete_state_watcher(w);
+  }
+}
+
+static void watch_complete(void *pw, int success) { partly_done(pw, 1); }
+
+static void timeout_complete(void *pw, int success) { partly_done(pw, 0); }
+
+void grpc_channel_watch_connectivity_state(
+    grpc_channel *channel, grpc_connectivity_state last_observed_state,
+    gpr_timespec deadline, grpc_completion_queue *cq, void *tag) {
+  grpc_channel_element *client_channel_elem =
+      grpc_channel_stack_last_element(grpc_channel_get_channel_stack(channel));
+  state_watcher *w = gpr_malloc(sizeof(*w));
+
+  grpc_cq_begin_op(cq);
+
+  gpr_mu_init(&w->mu);
+  grpc_iomgr_closure_init(&w->on_complete, watch_complete, w);
+  w->phase = WAITING;
+  w->state = last_observed_state;
+  w->success = 0;
+  w->cq = cq;
+  w->tag = tag;
+  w->channel = channel;
+
+  grpc_alarm_init(
+      &w->alarm, gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC), 
+      timeout_complete, w, gpr_now(GPR_CLOCK_MONOTONIC));
+
+  if (client_channel_elem->filter != &grpc_client_channel_filter) {
+    gpr_log(GPR_ERROR,
+            "grpc_channel_watch_connectivity_state called on something that is "
+            "not a client channel, but '%s'",
+            client_channel_elem->filter->name);
+    grpc_iomgr_add_delayed_callback(&w->on_complete, 1);
+  } else {
+    GRPC_CHANNEL_INTERNAL_REF(channel, "watch_connectivity");
+    grpc_client_channel_add_interested_party(client_channel_elem, grpc_cq_pollset(cq));
+    grpc_client_channel_watch_connectivity_state(client_channel_elem, &w->state,
+                                                 &w->on_complete);
+  }
+}
diff --git a/src/core/surface/channel_create.c b/src/core/surface/channel_create.c
index e205f0a9f8..707d615688 100644
--- a/src/core/surface/channel_create.c
+++ b/src/core/surface/channel_create.c
@@ -40,6 +40,7 @@
 
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
+#include "src/core/channel/compress_filter.h"
 #include "src/core/channel/http_client_filter.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/iomgr/tcp_client.h"
@@ -108,6 +109,7 @@ typedef struct {
   gpr_refcount refs;
   grpc_mdctx *mdctx;
   grpc_channel_args *merge_args;
+  grpc_channel *master;
 } subchannel_factory;
 
 static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
@@ -118,6 +120,7 @@ static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
 static void subchannel_factory_unref(grpc_subchannel_factory *scf) {
   subchannel_factory *f = (subchannel_factory *)scf;
   if (gpr_unref(&f->refs)) {
+    GRPC_CHANNEL_INTERNAL_UNREF(f->master, "subchannel_factory");
     grpc_channel_args_destroy(f->merge_args);
     grpc_mdctx_unref(f->mdctx);
     gpr_free(f);
@@ -136,6 +139,7 @@ static grpc_subchannel *subchannel_factory_create_subchannel(
   gpr_ref_init(&c->refs, 1);
   args->mdctx = f->mdctx;
   args->args = final_args;
+  args->master = f->master;
   s = grpc_subchannel_create(&c->base, args);
   grpc_connector_unref(&c->base);
   grpc_channel_args_destroy(final_args);
@@ -150,8 +154,8 @@ static const grpc_subchannel_factory_vtable subchannel_factory_vtable = {
    Asynchronously: - resolve target
                    - connect to it (trying alternatives as presented)
                    - perform handshakes */
-grpc_channel *grpc_channel_create(const char *target,
-                                  const grpc_channel_args *args) {
+grpc_channel *grpc_insecure_channel_create(const char *target,
+                                           const grpc_channel_args *args) {
   grpc_channel *channel = NULL;
 #define MAX_FILTERS 3
   const grpc_channel_filter *filters[MAX_FILTERS];
@@ -163,21 +167,26 @@ grpc_channel *grpc_channel_create(const char *target,
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
     } */
+  filters[n++] = &grpc_compress_filter;
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
 
+  channel =
+      grpc_channel_create_from_filters(target, filters, n, args, mdctx, 1);
+
   f = gpr_malloc(sizeof(*f));
   f->base.vtable = &subchannel_factory_vtable;
   gpr_ref_init(&f->refs, 1);
   grpc_mdctx_ref(mdctx);
   f->mdctx = mdctx;
   f->merge_args = grpc_channel_args_copy(args);
+  f->master = channel;
+  GRPC_CHANNEL_INTERNAL_REF(f->master, "subchannel_factory");
   resolver = grpc_resolver_create(target, &f->base);
   if (!resolver) {
     return NULL;
   }
 
-  channel = grpc_channel_create_from_filters(filters, n, args, mdctx, 1);
   grpc_client_channel_set_resolver(grpc_channel_get_channel_stack(channel),
                                    resolver);
   GRPC_RESOLVER_UNREF(resolver, "create");
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index c67f75fc5c..3f60b0b0ba 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -116,7 +116,7 @@ void grpc_cq_begin_op(grpc_completion_queue *cc) {
 void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
                     void (*done)(void *done_arg, grpc_cq_completion *storage),
                     void *done_arg, grpc_cq_completion *storage) {
-  int shutdown = gpr_unref(&cc->pending_events);
+  int shutdown;
 
   storage->tag = tag;
   storage->done = done;
@@ -124,15 +124,15 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
   storage->next =
       ((gpr_uintptr)&cc->completed_head) | ((gpr_uintptr)(success != 0));
 
+  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+  shutdown = gpr_unref(&cc->pending_events);
   if (!shutdown) {
-    gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
     cc->completed_tail->next =
         ((gpr_uintptr)storage) | (1u & (gpr_uintptr)cc->completed_tail->next);
     cc->completed_tail = storage;
     grpc_pollset_kick(&cc->pollset);
     gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
   } else {
-    gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
     cc->completed_tail->next =
         ((gpr_uintptr)storage) | (1u & (gpr_uintptr)cc->completed_tail->next);
     cc->completed_tail = storage;
@@ -148,6 +148,8 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
                                       gpr_timespec deadline) {
   grpc_event ret;
 
+  deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
+
   GRPC_CQ_INTERNAL_REF(cc, "next");
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
@@ -188,6 +190,8 @@ grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
   grpc_cq_completion *c;
   grpc_cq_completion *prev;
 
+  deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
+
   GRPC_CQ_INTERNAL_REF(cc, "pluck");
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
@@ -260,8 +264,9 @@ grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc) {
 void grpc_cq_hack_spin_pollset(grpc_completion_queue *cc) {
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   grpc_pollset_kick(&cc->pollset);
-  grpc_pollset_work(&cc->pollset, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                                               gpr_time_from_millis(100)));
+  grpc_pollset_work(&cc->pollset,
+                    gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                 gpr_time_from_millis(100, GPR_TIMESPAN)));
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
 }
 
diff --git a/src/core/surface/init.c b/src/core/surface/init.c
index 04e27d30ac..442bc72f21 100644
--- a/src/core/surface/init.c
+++ b/src/core/surface/init.c
@@ -39,6 +39,7 @@
 #include "src/core/channel/channel_stack.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/client_config/resolvers/dns_resolver.h"
+#include "src/core/client_config/resolvers/sockaddr_resolver.h"
 #include "src/core/debug/trace.h"
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/profiling/timers.h"
@@ -46,10 +47,7 @@
 #include "src/core/surface/init.h"
 #include "src/core/surface/surface_trace.h"
 #include "src/core/transport/chttp2_transport.h"
-
-#ifdef GPR_POSIX_SOCKET
-#include "src/core/client_config/resolvers/unix_resolver_posix.h"
-#endif
+#include "src/core/transport/connectivity_state.h"
 
 static gpr_once g_basic_init = GPR_ONCE_INIT;
 static gpr_mu g_init_mu;
@@ -68,6 +66,8 @@ void grpc_init(void) {
     gpr_time_init();
     grpc_resolver_registry_init("dns:///");
     grpc_register_resolver_type("dns", grpc_dns_resolver_factory_create());
+    grpc_register_resolver_type("ipv4", grpc_ipv4_resolver_factory_create());
+    grpc_register_resolver_type("ipv6", grpc_ipv6_resolver_factory_create());
 #ifdef GPR_POSIX_SOCKET
     grpc_register_resolver_type("unix", grpc_unix_resolver_factory_create());
 #endif
@@ -76,11 +76,15 @@ void grpc_init(void) {
     grpc_register_tracer("http", &grpc_http_trace);
     grpc_register_tracer("flowctl", &grpc_flowctl_trace);
     grpc_register_tracer("batch", &grpc_trace_batch);
+    grpc_register_tracer("connectivity_state", &grpc_connectivity_state_trace);
     grpc_security_pre_init();
     grpc_iomgr_init();
     grpc_tracer_init("GRPC_TRACE");
-    if (census_initialize(CENSUS_NONE)) {
-      gpr_log(GPR_ERROR, "Could not initialize census.");
+    /* Only initialize census if noone else has. */
+    if (census_enabled() == CENSUS_FEATURE_NONE) {
+      if (census_initialize(census_supported())) { /* enable all features. */
+        gpr_log(GPR_ERROR, "Could not initialize census.");
+      }
     }
     grpc_timers_global_init();
   }
diff --git a/src/core/surface/lame_client.c b/src/core/surface/lame_client.c
index 3dd56fe5a9..c4215a2cfb 100644
--- a/src/core/surface/lame_client.c
+++ b/src/core/surface/lame_client.c
@@ -47,7 +47,10 @@ typedef struct {
   grpc_linked_mdelem details;
 } call_data;
 
-typedef struct { grpc_mdctx *mdctx; } channel_data;
+typedef struct {
+  grpc_mdctx *mdctx;
+  grpc_channel *master;
+} channel_data;
 
 static void lame_start_transport_stream_op(grpc_call_element *elem,
                                            grpc_transport_stream_op *op) {
@@ -72,7 +75,7 @@ static void lame_start_transport_stream_op(grpc_call_element *elem,
     mdb.list.head = &calld->status;
     mdb.list.tail = &calld->details;
     mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future;
+    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
     grpc_sopb_add_metadata(op->recv_ops, mdb);
     *op->recv_state = GRPC_STREAM_CLOSED;
     op->on_done_recv->cb(op->on_done_recv->cb_arg, 1);
@@ -82,6 +85,11 @@ static void lame_start_transport_stream_op(grpc_call_element *elem,
   }
 }
 
+static char *lame_get_peer(grpc_call_element *elem) {
+  channel_data *chand = elem->channel_data;
+  return grpc_channel_get_target(chand->master);
+}
+
 static void lame_start_transport_op(grpc_channel_element *elem,
                                     grpc_transport_op *op) {
   if (op->on_connectivity_state_change) {
@@ -112,6 +120,7 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   GPR_ASSERT(is_first);
   GPR_ASSERT(is_last);
   chand->mdctx = mdctx;
+  chand->master = master;
 }
 
 static void destroy_channel_elem(grpc_channel_element *elem) {}
@@ -125,11 +134,12 @@ static const grpc_channel_filter lame_filter = {
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    lame_get_peer,
     "lame-client",
 };
 
-grpc_channel *grpc_lame_client_channel_create(void) {
+grpc_channel *grpc_lame_client_channel_create(const char *target) {
   static const grpc_channel_filter *filters[] = {&lame_filter};
-  return grpc_channel_create_from_filters(filters, 1, NULL, grpc_mdctx_create(),
-                                          1);
+  return grpc_channel_create_from_filters(target, filters, 1, NULL,
+                                          grpc_mdctx_create(), 1);
 }
diff --git a/src/core/surface/secure_channel_create.c b/src/core/surface/secure_channel_create.c
index f3c7d8397b..1f89353025 100644
--- a/src/core/surface/secure_channel_create.c
+++ b/src/core/surface/secure_channel_create.c
@@ -40,6 +40,7 @@
 
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
+#include "src/core/channel/compress_filter.h"
 #include "src/core/channel/http_client_filter.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/iomgr/tcp_client.h"
@@ -133,6 +134,7 @@ typedef struct {
   grpc_mdctx *mdctx;
   grpc_channel_args *merge_args;
   grpc_channel_security_connector *security_connector;
+  grpc_channel *master;
 } subchannel_factory;
 
 static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
@@ -145,6 +147,7 @@ static void subchannel_factory_unref(grpc_subchannel_factory *scf) {
   if (gpr_unref(&f->refs)) {
     GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
                                   "subchannel_factory");
+    GRPC_CHANNEL_INTERNAL_UNREF(f->master, "subchannel_factory");
     grpc_channel_args_destroy(f->merge_args);
     grpc_mdctx_unref(f->mdctx);
     gpr_free(f);
@@ -164,6 +167,7 @@ static grpc_subchannel *subchannel_factory_create_subchannel(
   gpr_ref_init(&c->refs, 1);
   args->mdctx = f->mdctx;
   args->args = final_args;
+  args->master = f->master;
   s = grpc_subchannel_create(&c->base, args);
   grpc_connector_unref(&c->base);
   grpc_channel_args_destroy(final_args);
@@ -195,13 +199,13 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
 
   if (grpc_find_security_connector_in_args(args) != NULL) {
     gpr_log(GPR_ERROR, "Cannot set security context in channel args.");
-    return grpc_lame_client_channel_create();
+    return grpc_lame_client_channel_create(target);
   }
 
   if (grpc_credentials_create_security_connector(
           creds, target, args, NULL, &connector, &new_args_from_connector) !=
       GRPC_SECURITY_OK) {
-    return grpc_lame_client_channel_create();
+    return grpc_lame_client_channel_create(target);
   }
   mdctx = grpc_mdctx_create();
 
@@ -213,9 +217,13 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
     } */
+  filters[n++] = &grpc_compress_filter;
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
 
+  channel =
+      grpc_channel_create_from_filters(target, filters, n, args_copy, mdctx, 1);
+
   f = gpr_malloc(sizeof(*f));
   f->base.vtable = &subchannel_factory_vtable;
   gpr_ref_init(&f->refs, 1);
@@ -224,12 +232,13 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   GRPC_SECURITY_CONNECTOR_REF(&connector->base, "subchannel_factory");
   f->security_connector = connector;
   f->merge_args = grpc_channel_args_copy(args_copy);
+  f->master = channel;
+  GRPC_CHANNEL_INTERNAL_REF(channel, "subchannel_factory");
   resolver = grpc_resolver_create(target, &f->base);
   if (!resolver) {
     return NULL;
   }
 
-  channel = grpc_channel_create_from_filters(filters, n, args_copy, mdctx, 1);
   grpc_client_channel_set_resolver(grpc_channel_get_channel_stack(channel),
                                    resolver);
   GRPC_RESOLVER_UNREF(resolver, "create");
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 4dc51bf031..c370a9b8ab 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -36,22 +36,22 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
 #include "src/core/channel/census_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/connected_channel.h"
 #include "src/core/iomgr/iomgr.h"
+#include "src/core/support/stack_lockfree.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/call.h"
 #include "src/core/surface/channel.h"
 #include "src/core/surface/completion_queue.h"
 #include "src/core/surface/init.h"
 #include "src/core/transport/metadata.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/useful.h>
-
-typedef enum { PENDING_START, CALL_LIST_COUNT } call_list;
 
 typedef struct listener {
   void *arg;
@@ -74,8 +74,8 @@ typedef enum { BATCH_CALL, REGISTERED_CALL } requested_call_type;
 
 typedef struct requested_call {
   requested_call_type type;
-  struct requested_call *next;
   void *tag;
+  grpc_server *server;
   grpc_completion_queue *cq_bound_to_call;
   grpc_completion_queue *cq_for_notification;
   grpc_call **call;
@@ -94,14 +94,6 @@ typedef struct requested_call {
   } data;
 } requested_call;
 
-struct registered_method {
-  char *method;
-  char *host;
-  call_data *pending;
-  requested_call *requests;
-  registered_method *next;
-};
-
 typedef struct channel_registered_method {
   registered_method *server_registered_method;
   grpc_mdstr *method;
@@ -130,44 +122,6 @@ typedef struct shutdown_tag {
   grpc_cq_completion completion;
 } shutdown_tag;
 
-struct grpc_server {
-  size_t channel_filter_count;
-  const grpc_channel_filter **channel_filters;
-  grpc_channel_args *channel_args;
-
-  grpc_completion_queue **cqs;
-  grpc_pollset **pollsets;
-  size_t cq_count;
-
-  /* The two following mutexes control access to server-state
-     mu_global controls access to non-call-related state (e.g., channel state)
-     mu_call controls access to call-related state (e.g., the call lists)
-
-     If they are ever required to be nested, you must lock mu_global
-     before mu_call. This is currently used in shutdown processing
-     (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
-  gpr_mu mu_global; /* mutex for server and channel state */
-  gpr_mu mu_call;   /* mutex for call-specific state */
-
-  registered_method *registered_methods;
-  requested_call *requests;
-
-  gpr_uint8 shutdown;
-  gpr_uint8 shutdown_published;
-  size_t num_shutdown_tags;
-  shutdown_tag *shutdown_tags;
-
-  call_data *lists[CALL_LIST_COUNT];
-  channel_data root_channel_data;
-
-  listener *listeners;
-  int listeners_destroyed;
-  gpr_refcount internal_refcount;
-
-  /** when did we print the last shutdown progress message */
-  gpr_timespec last_shutdown_message_time;
-};
-
 typedef enum {
   /* waiting for metadata */
   NOT_STARTED,
@@ -179,6 +133,8 @@ typedef enum {
   ZOMBIED
 } call_state;
 
+typedef struct request_matcher request_matcher;
+
 struct call_data {
   grpc_call *call;
 
@@ -201,8 +157,20 @@ struct call_data {
   grpc_iomgr_closure server_on_recv;
   grpc_iomgr_closure kill_zombie_closure;
 
-  call_data **root[CALL_LIST_COUNT];
-  call_link links[CALL_LIST_COUNT];
+  call_data *pending_next;
+};
+
+struct request_matcher {
+  call_data *pending_head;
+  call_data *pending_tail;
+  gpr_stack_lockfree *requests;
+};
+
+struct registered_method {
+  char *method;
+  char *host;
+  request_matcher request_matcher;
+  registered_method *next;
 };
 
 typedef struct {
@@ -210,6 +178,48 @@ typedef struct {
   size_t num_channels;
 } channel_broadcaster;
 
+struct grpc_server {
+  size_t channel_filter_count;
+  const grpc_channel_filter **channel_filters;
+  grpc_channel_args *channel_args;
+
+  grpc_completion_queue **cqs;
+  grpc_pollset **pollsets;
+  size_t cq_count;
+
+  /* The two following mutexes control access to server-state
+     mu_global controls access to non-call-related state (e.g., channel state)
+     mu_call controls access to call-related state (e.g., the call lists)
+
+     If they are ever required to be nested, you must lock mu_global
+     before mu_call. This is currently used in shutdown processing
+     (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
+  gpr_mu mu_global; /* mutex for server and channel state */
+  gpr_mu mu_call;   /* mutex for call-specific state */
+
+  registered_method *registered_methods;
+  request_matcher unregistered_request_matcher;
+  /** free list of available requested_calls indices */
+  gpr_stack_lockfree *request_freelist;
+  /** requested call backing data */
+  requested_call *requested_calls;
+  int max_requested_calls;
+
+  gpr_atm shutdown_flag;
+  gpr_uint8 shutdown_published;
+  size_t num_shutdown_tags;
+  shutdown_tag *shutdown_tags;
+
+  channel_data root_channel_data;
+
+  listener *listeners;
+  int listeners_destroyed;
+  gpr_refcount internal_refcount;
+
+  /** when did we print the last shutdown progress message */
+  gpr_timespec last_shutdown_message_time;
+};
+
 #define SERVER_FROM_CALL_ELEM(elem) \
   (((channel_data *)(elem)->channel_data)->server)
 
@@ -220,7 +230,9 @@ static void fail_call(grpc_server *server, requested_call *rc);
    hold mu_call */
 static void maybe_finish_shutdown(grpc_server *server);
 
-/* channel broadcaster */
+/*
+ * channel broadcaster
+ */
 
 /* assumes server locked */
 static void channel_broadcaster_init(grpc_server *s, channel_broadcaster *cb) {
@@ -281,55 +293,44 @@ static void channel_broadcaster_shutdown(channel_broadcaster *cb,
   gpr_free(cb->channels);
 }
 
-/* call list */
+/*
+ * request_matcher
+ */
 
-static int call_list_join(call_data **root, call_data *call, call_list list) {
-  GPR_ASSERT(!call->root[list]);
-  call->root[list] = root;
-  if (!*root) {
-    *root = call;
-    call->links[list].next = call->links[list].prev = call;
-  } else {
-    call->links[list].next = *root;
-    call->links[list].prev = (*root)->links[list].prev;
-    call->links[list].next->links[list].prev =
-        call->links[list].prev->links[list].next = call;
-  }
-  return 1;
+static void request_matcher_init(request_matcher *request_matcher,
+                                 int entries) {
+  memset(request_matcher, 0, sizeof(*request_matcher));
+  request_matcher->requests = gpr_stack_lockfree_create(entries);
 }
 
-static call_data *call_list_remove_head(call_data **root, call_list list) {
-  call_data *out = *root;
-  if (out) {
-    out->root[list] = NULL;
-    if (out->links[list].next == out) {
-      *root = NULL;
-    } else {
-      *root = out->links[list].next;
-      out->links[list].next->links[list].prev = out->links[list].prev;
-      out->links[list].prev->links[list].next = out->links[list].next;
-    }
-  }
-  return out;
+static void request_matcher_destroy(request_matcher *request_matcher) {
+  GPR_ASSERT(gpr_stack_lockfree_pop(request_matcher->requests) == -1);
+  gpr_stack_lockfree_destroy(request_matcher->requests);
 }
 
-static int call_list_remove(call_data *call, call_list list) {
-  call_data **root = call->root[list];
-  if (root == NULL) return 0;
-  call->root[list] = NULL;
-  if (*root == call) {
-    *root = call->links[list].next;
-    if (*root == call) {
-      *root = NULL;
-      return 1;
-    }
+static void kill_zombie(void *elem, int success) {
+  grpc_call_destroy(grpc_call_from_top_element(elem));
+}
+
+static void request_matcher_zombify_all_pending_calls(
+    request_matcher *request_matcher) {
+  while (request_matcher->pending_head) {
+    call_data *calld = request_matcher->pending_head;
+    request_matcher->pending_head = calld->pending_next;
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_iomgr_closure_init(
+        &calld->kill_zombie_closure, kill_zombie,
+        grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+    grpc_iomgr_add_callback(&calld->kill_zombie_closure);
   }
-  GPR_ASSERT(*root != call);
-  call->links[list].next->links[list].prev = call->links[list].prev;
-  call->links[list].prev->links[list].next = call->links[list].next;
-  return 1;
 }
 
+/*
+ * server proper
+ */
+
 static void server_ref(grpc_server *server) {
   gpr_ref(&server->internal_refcount);
 }
@@ -343,6 +344,7 @@ static void server_delete(grpc_server *server) {
   gpr_free(server->channel_filters);
   while ((rm = server->registered_methods) != NULL) {
     server->registered_methods = rm->next;
+    request_matcher_destroy(&rm->request_matcher);
     gpr_free(rm->method);
     gpr_free(rm->host);
     gpr_free(rm);
@@ -350,9 +352,12 @@ static void server_delete(grpc_server *server) {
   for (i = 0; i < server->cq_count; i++) {
     GRPC_CQ_INTERNAL_UNREF(server->cqs[i], "server");
   }
+  request_matcher_destroy(&server->unregistered_request_matcher);
+  gpr_stack_lockfree_destroy(server->request_freelist);
   gpr_free(server->cqs);
   gpr_free(server->pollsets);
   gpr_free(server->shutdown_tags);
+  gpr_free(server->requested_calls);
   gpr_free(server);
 }
 
@@ -391,25 +396,38 @@ static void destroy_channel(channel_data *chand) {
 }
 
 static void finish_start_new_rpc(grpc_server *server, grpc_call_element *elem,
-                                 call_data **pending_root,
-                                 requested_call **requests) {
-  requested_call *rc;
+                                 request_matcher *request_matcher) {
   call_data *calld = elem->call_data;
-  gpr_mu_lock(&server->mu_call);
-  rc = *requests;
-  if (rc == NULL) {
+  int request_id;
+
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_iomgr_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
+    grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+    return;
+  }
+
+  request_id = gpr_stack_lockfree_pop(request_matcher->requests);
+  if (request_id == -1) {
+    gpr_mu_lock(&server->mu_call);
     gpr_mu_lock(&calld->mu_state);
     calld->state = PENDING;
     gpr_mu_unlock(&calld->mu_state);
-    call_list_join(pending_root, calld, PENDING_START);
+    if (request_matcher->pending_head == NULL) {
+      request_matcher->pending_tail = request_matcher->pending_head = calld;
+    } else {
+      request_matcher->pending_tail->pending_next = calld;
+      request_matcher->pending_tail = calld;
+    }
+    calld->pending_next = NULL;
     gpr_mu_unlock(&server->mu_call);
   } else {
-    *requests = rc->next;
     gpr_mu_lock(&calld->mu_state);
     calld->state = ACTIVATED;
     gpr_mu_unlock(&calld->mu_state);
-    gpr_mu_unlock(&server->mu_call);
-    begin_call(server, calld, rc);
+    begin_call(server, calld, &server->requested_calls[request_id]);
   }
 }
 
@@ -431,8 +449,8 @@ static void start_new_rpc(grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != calld->host) continue;
       if (rm->method != calld->path) continue;
-      finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requests);
+      finish_start_new_rpc(server, elem,
+                           &rm->server_registered_method->request_matcher);
       return;
     }
     /* check for a wildcard method definition (no host set) */
@@ -443,17 +461,12 @@ static void start_new_rpc(grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != NULL) continue;
       if (rm->method != calld->path) continue;
-      finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requests);
+      finish_start_new_rpc(server, elem,
+                           &rm->server_registered_method->request_matcher);
       return;
     }
   }
-  finish_start_new_rpc(server, elem, &server->lists[PENDING_START],
-                       &server->requests);
-}
-
-static void kill_zombie(void *elem, int success) {
-  grpc_call_destroy(grpc_call_from_top_element(elem));
+  finish_start_new_rpc(server, elem, &server->unregistered_request_matcher);
 }
 
 static int num_listeners(grpc_server *server) {
@@ -481,15 +494,15 @@ static int num_channels(grpc_server *server) {
 
 static void maybe_finish_shutdown(grpc_server *server) {
   size_t i;
-  if (!server->shutdown || server->shutdown_published) {
+  if (!gpr_atm_acq_load(&server->shutdown_flag) || server->shutdown_published) {
     return;
   }
 
   if (server->root_channel_data.next != &server->root_channel_data ||
       server->listeners_destroyed < num_listeners(server)) {
-    if (gpr_time_cmp(
-            gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), server->last_shutdown_message_time),
-            gpr_time_from_seconds(1)) >= 0) {
+    if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
+                                  server->last_shutdown_message_time),
+                     gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
       server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
       gpr_log(GPR_DEBUG,
               "Waiting for %d channels and %d/%d listeners to be destroyed"
@@ -526,7 +539,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
 static void server_on_recv(void *ptr, int success) {
   grpc_call_element *elem = ptr;
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
+  gpr_timespec op_deadline;
 
   if (success && !calld->got_initial_metadata) {
     size_t i;
@@ -536,11 +549,15 @@ static void server_on_recv(void *ptr, int success) {
       grpc_stream_op *op = &ops[i];
       if (op->type != GRPC_OP_METADATA) continue;
       grpc_metadata_batch_filter(&op->data.metadata, server_filter, elem);
-      if (0 != gpr_time_cmp(op->data.metadata.deadline, gpr_inf_future)) {
+      op_deadline = op->data.metadata.deadline;
+      if (0 !=
+          gpr_time_cmp(op_deadline, gpr_inf_future(op_deadline.clock_type))) {
         calld->deadline = op->data.metadata.deadline;
       }
-      calld->got_initial_metadata = 1;
-      start_new_rpc(elem);
+      if (calld->host && calld->path) {
+        calld->got_initial_metadata = 1;
+        start_new_rpc(elem);
+      }
       break;
     }
   }
@@ -571,11 +588,8 @@ static void server_on_recv(void *ptr, int success) {
       } else if (calld->state == PENDING) {
         calld->state = ZOMBIED;
         gpr_mu_unlock(&calld->mu_state);
-        gpr_mu_lock(&chand->server->mu_call);
-        call_list_remove(calld, PENDING_START);
-        gpr_mu_unlock(&chand->server->mu_call);
-        grpc_iomgr_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
-        grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+        /* zombied call will be destroyed when it's removed from the pending
+           queue... later */
       } else {
         gpr_mu_unlock(&calld->mu_state);
       }
@@ -610,7 +624,7 @@ static void accept_stream(void *cd, grpc_transport *transport,
   channel_data *chand = cd;
   /* create a call */
   grpc_call_create(chand->channel, NULL, transport_server_data, NULL, 0,
-                   gpr_inf_future);
+                   gpr_inf_future(GPR_CLOCK_REALTIME));
 }
 
 static void channel_connectivity_changed(void *cd, int iomgr_status_ignored) {
@@ -638,7 +652,7 @@ static void init_call_elem(grpc_call_element *elem,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   memset(calld, 0, sizeof(call_data));
-  calld->deadline = gpr_inf_future;
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
   calld->call = grpc_call_from_top_element(elem);
   gpr_mu_init(&calld->mu_state);
 
@@ -653,11 +667,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
 
-  if (calld->state == PENDING) {
-    gpr_mu_lock(&chand->server->mu_call);
-    call_list_remove(elem->call_data, PENDING_START);
-    gpr_mu_unlock(&chand->server->mu_call);
-  }
+  GPR_ASSERT(calld->state != PENDING);
 
   if (calld->host) {
     GRPC_MDSTR_UNREF(calld->host);
@@ -680,8 +690,8 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   GPR_ASSERT(!is_last);
   chand->server = NULL;
   chand->channel = NULL;
-  chand->path_key = grpc_mdstr_from_string(metadata_context, ":path");
-  chand->authority_key = grpc_mdstr_from_string(metadata_context, ":authority");
+  chand->path_key = grpc_mdstr_from_string(metadata_context, ":path", 0);
+  chand->authority_key = grpc_mdstr_from_string(metadata_context, ":authority", 0);
   chand->next = chand->prev = chand;
   chand->registered_methods = NULL;
   chand->connectivity_state = GRPC_CHANNEL_IDLE;
@@ -725,6 +735,7 @@ static const grpc_channel_filter server_surface_filter = {
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    grpc_call_next_get_peer,
     "server",
 };
 
@@ -742,9 +753,9 @@ void grpc_server_register_completion_queue(grpc_server *server,
   server->cqs[n] = cq;
 }
 
-grpc_server *grpc_server_create_from_filters(grpc_channel_filter **filters,
-                                             size_t filter_count,
-                                             const grpc_channel_args *args) {
+grpc_server *grpc_server_create_from_filters(
+    const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *args) {
   size_t i;
   /* TODO(census): restore this once we finalize census filter etc.
      int census_enabled = grpc_channel_args_is_census_enabled(args); */
@@ -764,6 +775,18 @@ grpc_server *grpc_server_create_from_filters(grpc_channel_filter **filters,
   server->root_channel_data.next = server->root_channel_data.prev =
       &server->root_channel_data;
 
+  /* TODO(ctiller): expose a channel_arg for this */
+  server->max_requested_calls = 32768;
+  server->request_freelist =
+      gpr_stack_lockfree_create(server->max_requested_calls);
+  for (i = 0; i < (size_t)server->max_requested_calls; i++) {
+    gpr_stack_lockfree_push(server->request_freelist, i);
+  }
+  request_matcher_init(&server->unregistered_request_matcher,
+                       server->max_requested_calls);
+  server->requested_calls = gpr_malloc(server->max_requested_calls *
+                                       sizeof(*server->requested_calls));
+
   /* Server filter stack is:
 
      server_surface_filter - for making surface API calls
@@ -811,6 +834,7 @@ void *grpc_server_register_method(grpc_server *server, const char *method,
   }
   m = gpr_malloc(sizeof(registered_method));
   memset(m, 0, sizeof(*m));
+  request_matcher_init(&m->request_matcher, server->max_requested_calls);
   m->method = gpr_strdup(method);
   m->host = gpr_strdup(host);
   m->next = server->registered_methods;
@@ -868,8 +892,8 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
     grpc_transport_perform_op(transport, &op);
   }
 
-  channel =
-      grpc_channel_create_from_filters(filters, num_filters, args, mdctx, 0);
+  channel = grpc_channel_create_from_filters(NULL, filters, num_filters, args,
+                                             mdctx, 0);
   chand = (channel_data *)grpc_channel_stack_element(
               grpc_channel_get_channel_stack(channel), 0)
               ->channel_data;
@@ -889,8 +913,8 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
     chand->registered_methods = gpr_malloc(alloc);
     memset(chand->registered_methods, 0, alloc);
     for (rm = s->registered_methods; rm; rm = rm->next) {
-      host = rm->host ? grpc_mdstr_from_string(mdctx, rm->host) : NULL;
-      method = grpc_mdstr_from_string(mdctx, rm->method);
+      host = rm->host ? grpc_mdstr_from_string(mdctx, rm->host, 0) : NULL;
+      method = grpc_mdstr_from_string(mdctx, rm->method, 0);
       hash = GRPC_MDSTR_KV_HASH(host ? host->hash : 0, method->hash);
       for (probes = 0; chand->registered_methods[(hash + probes) % slots]
                            .server_registered_method != NULL;
@@ -926,13 +950,51 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
   grpc_transport_perform_op(transport, &op);
 }
 
+typedef struct {
+  requested_call **requests;
+  size_t count;
+  size_t capacity;
+} request_killer;
+
+static void request_killer_init(request_killer *rk) {
+  memset(rk, 0, sizeof(*rk));
+}
+
+static void request_killer_add(request_killer *rk, requested_call *rc) {
+  if (rk->capacity == rk->count) {
+    rk->capacity = GPR_MAX(8, rk->capacity * 2);
+    rk->requests =
+        gpr_realloc(rk->requests, rk->capacity * sizeof(*rk->requests));
+  }
+  rk->requests[rk->count++] = rc;
+}
+
+static void request_killer_add_request_matcher(request_killer *rk,
+                                               grpc_server *server,
+                                               request_matcher *rm) {
+  int request_id;
+  while ((request_id = gpr_stack_lockfree_pop(rm->requests)) != -1) {
+    request_killer_add(rk, &server->requested_calls[request_id]);
+  }
+}
+
+static void request_killer_run(request_killer *rk, grpc_server *server) {
+  size_t i;
+  for (i = 0; i < rk->count; i++) {
+    fail_call(server, rk->requests[i]);
+  }
+  gpr_free(rk->requests);
+}
+
 void grpc_server_shutdown_and_notify(grpc_server *server,
                                      grpc_completion_queue *cq, void *tag) {
   listener *l;
-  requested_call *requests = NULL;
   registered_method *rm;
   shutdown_tag *sdt;
   channel_broadcaster broadcaster;
+  request_killer reqkill;
+
+  GRPC_SERVER_LOG_SHUTDOWN(GPR_INFO, server, cq, tag);
 
   /* lock, and gather up some stuff to do */
   gpr_mu_lock(&server->mu_global);
@@ -943,7 +1005,7 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   sdt = &server->shutdown_tags[server->num_shutdown_tags++];
   sdt->tag = tag;
   sdt->cq = cq;
-  if (server->shutdown) {
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
     gpr_mu_unlock(&server->mu_global);
     return;
   }
@@ -951,31 +1013,26 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
 
   channel_broadcaster_init(server, &broadcaster);
+  request_killer_init(&reqkill);
 
   /* collect all unregistered then registered calls */
   gpr_mu_lock(&server->mu_call);
-  requests = server->requests;
-  server->requests = NULL;
+  request_killer_add_request_matcher(&reqkill, server,
+                                     &server->unregistered_request_matcher);
+  request_matcher_zombify_all_pending_calls(
+      &server->unregistered_request_matcher);
   for (rm = server->registered_methods; rm; rm = rm->next) {
-    while (rm->requests != NULL) {
-      requested_call *c = rm->requests;
-      rm->requests = c->next;
-      c->next = requests;
-      requests = c;
-    }
+    request_killer_add_request_matcher(&reqkill, server, &rm->request_matcher);
+    request_matcher_zombify_all_pending_calls(&rm->request_matcher);
   }
   gpr_mu_unlock(&server->mu_call);
 
-  server->shutdown = 1;
+  gpr_atm_rel_store(&server->shutdown_flag, 1);
   maybe_finish_shutdown(server);
   gpr_mu_unlock(&server->mu_global);
 
   /* terminate all the requested calls */
-  while (requests != NULL) {
-    requested_call *next = requests->next;
-    fail_call(server, requests);
-    requests = next;
-  }
+  request_killer_run(&reqkill, server);
 
   /* Shutdown listeners */
   for (l = server->listeners; l; l = l->next) {
@@ -1007,7 +1064,7 @@ void grpc_server_destroy(grpc_server *server) {
   listener *l;
 
   gpr_mu_lock(&server->mu_global);
-  GPR_ASSERT(server->shutdown || !server->listeners);
+  GPR_ASSERT(gpr_atm_acq_load(&server->shutdown_flag) || !server->listeners);
   GPR_ASSERT(server->listeners_destroyed == num_listeners(server));
 
   while (server->listeners) {
@@ -1037,39 +1094,55 @@ void grpc_server_add_listener(grpc_server *server, void *arg,
 static grpc_call_error queue_call_request(grpc_server *server,
                                           requested_call *rc) {
   call_data *calld = NULL;
-  requested_call **requests = NULL;
-  gpr_mu_lock(&server->mu_call);
-  if (server->shutdown) {
-    gpr_mu_unlock(&server->mu_call);
+  request_matcher *request_matcher = NULL;
+  int request_id;
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    fail_call(server, rc);
+    return GRPC_CALL_OK;
+  }
+  request_id = gpr_stack_lockfree_pop(server->request_freelist);
+  if (request_id == -1) {
+    /* out of request ids: just fail this one */
     fail_call(server, rc);
     return GRPC_CALL_OK;
   }
   switch (rc->type) {
     case BATCH_CALL:
-      calld =
-          call_list_remove_head(&server->lists[PENDING_START], PENDING_START);
-      requests = &server->requests;
+      request_matcher = &server->unregistered_request_matcher;
       break;
     case REGISTERED_CALL:
-      calld = call_list_remove_head(
-          &rc->data.registered.registered_method->pending, PENDING_START);
-      requests = &rc->data.registered.registered_method->requests;
+      request_matcher = &rc->data.registered.registered_method->request_matcher;
       break;
   }
-  if (calld != NULL) {
-    gpr_mu_unlock(&server->mu_call);
-    gpr_mu_lock(&calld->mu_state);
-    GPR_ASSERT(calld->state == PENDING);
-    calld->state = ACTIVATED;
-    gpr_mu_unlock(&calld->mu_state);
-    begin_call(server, calld, rc);
-    return GRPC_CALL_OK;
-  } else {
-    rc->next = *requests;
-    *requests = rc;
+  server->requested_calls[request_id] = *rc;
+  gpr_free(rc);
+  if (gpr_stack_lockfree_push(request_matcher->requests, request_id)) {
+    /* this was the first queued request: we need to lock and start
+       matching calls */
+    gpr_mu_lock(&server->mu_call);
+    while ((calld = request_matcher->pending_head) != NULL) {
+      request_id = gpr_stack_lockfree_pop(request_matcher->requests);
+      if (request_id == -1) break;
+      request_matcher->pending_head = calld->pending_next;
+      gpr_mu_unlock(&server->mu_call);
+      gpr_mu_lock(&calld->mu_state);
+      if (calld->state == ZOMBIED) {
+        gpr_mu_unlock(&calld->mu_state);
+        grpc_iomgr_closure_init(
+            &calld->kill_zombie_closure, kill_zombie,
+            grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+        grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+      } else {
+        GPR_ASSERT(calld->state == PENDING);
+        calld->state = ACTIVATED;
+        gpr_mu_unlock(&calld->mu_state);
+        begin_call(server, calld, &server->requested_calls[request_id]);
+      }
+      gpr_mu_lock(&server->mu_call);
+    }
     gpr_mu_unlock(&server->mu_call);
-    return GRPC_CALL_OK;
   }
+  return GRPC_CALL_OK;
 }
 
 grpc_call_error grpc_server_request_call(
@@ -1087,6 +1160,7 @@ grpc_call_error grpc_server_request_call(
   }
   grpc_cq_begin_op(cq_for_notification);
   rc->type = BATCH_CALL;
+  rc->server = server;
   rc->tag = tag;
   rc->cq_bound_to_call = cq_bound_to_call;
   rc->cq_for_notification = cq_for_notification;
@@ -1109,6 +1183,7 @@ grpc_call_error grpc_server_request_registered_call(
   }
   grpc_cq_begin_op(cq_for_notification);
   rc->type = REGISTERED_CALL;
+  rc->server = server;
   rc->tag = tag;
   rc->cq_bound_to_call = cq_bound_to_call;
   rc->cq_for_notification = cq_for_notification;
@@ -1188,7 +1263,18 @@ static void begin_call(grpc_server *server, call_data *calld,
 }
 
 static void done_request_event(void *req, grpc_cq_completion *c) {
-  gpr_free(req);
+  requested_call *rc = req;
+  grpc_server *server = rc->server;
+
+  if (rc >= server->requested_calls &&
+      rc < server->requested_calls + server->max_requested_calls) {
+    gpr_stack_lockfree_push(server->request_freelist,
+                            rc - server->requested_calls);
+  } else {
+    gpr_free(req);
+  }
+
+  server_unref(server);
 }
 
 static void fail_call(grpc_server *server, requested_call *rc) {
@@ -1201,6 +1287,7 @@ static void fail_call(grpc_server *server, requested_call *rc) {
       rc->data.registered.initial_metadata->count = 0;
       break;
   }
+  server_ref(server);
   grpc_cq_end_op(rc->cq_for_notification, rc->tag, 0, done_request_event, rc,
                  &rc->completion);
 }
@@ -1211,6 +1298,8 @@ static void publish_registered_or_batch(grpc_call *call, int success,
       grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
   requested_call *rc = prc;
   call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  server_ref(chand->server);
   grpc_cq_end_op(calld->cq_new, rc->tag, success, done_request_event, rc,
                  &rc->completion);
   GRPC_CALL_INTERNAL_UNREF(call, "server", 0);
diff --git a/src/core/surface/server.h b/src/core/surface/server.h
index 2899c6dea3..c638d682bb 100644
--- a/src/core/surface/server.h
+++ b/src/core/surface/server.h
@@ -39,9 +39,9 @@
 #include "src/core/transport/transport.h"
 
 /* Create a server */
-grpc_server *grpc_server_create_from_filters(grpc_channel_filter **filters,
-                                             size_t filter_count,
-                                             const grpc_channel_args *args);
+grpc_server *grpc_server_create_from_filters(
+    const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *args);
 
 /* Add a listener to the server: when the server starts, it will call start,
    and when it shuts down, it will call destroy */
diff --git a/src/core/surface/server_create.c b/src/core/surface/server_create.c
index b7390675ad..1e26c67693 100644
--- a/src/core/surface/server_create.c
+++ b/src/core/surface/server_create.c
@@ -34,7 +34,10 @@
 #include <grpc/grpc.h>
 #include "src/core/surface/completion_queue.h"
 #include "src/core/surface/server.h"
+#include "src/core/channel/compress_filter.h"
 
 grpc_server *grpc_server_create(const grpc_channel_args *args) {
-  return grpc_server_create_from_filters(NULL, 0, args);
+  const grpc_channel_filter *filters[] = {&grpc_compress_filter};
+  return grpc_server_create_from_filters(filters, GPR_ARRAY_SIZE(filters),
+                                         args);
 }
diff --git a/src/core/transport/chttp2/alpn.c b/src/core/transport/chttp2/alpn.c
index 3ccd5796ba..69da4e6718 100644
--- a/src/core/transport/chttp2/alpn.c
+++ b/src/core/transport/chttp2/alpn.c
@@ -36,8 +36,7 @@
 #include <grpc/support/useful.h>
 
 /* in order of preference */
-static const char *const supported_versions[] = {"h2", "h2-17", "h2-16",
-                                                 "h2-15", "h2-14"};
+static const char *const supported_versions[] = {"h2"};
 
 int grpc_chttp2_is_alpn_version_supported(const char *version, size_t size) {
   size_t i;
diff --git a/src/core/transport/chttp2/frame_data.c b/src/core/transport/chttp2/frame_data.c
index 7e3980159e..40bf2ebd79 100644
--- a/src/core/transport/chttp2/frame_data.c
+++ b/src/core/transport/chttp2/frame_data.c
@@ -76,6 +76,7 @@ grpc_chttp2_parse_error grpc_chttp2_data_parser_parse(
   gpr_uint8 *const end = GPR_SLICE_END_PTR(slice);
   gpr_uint8 *cur = beg;
   grpc_chttp2_data_parser *p = parser;
+  gpr_uint32 message_flags = 0;
 
   if (is_last && p->is_last_frame) {
     stream_parsing->received_close = 1;
@@ -91,11 +92,11 @@ grpc_chttp2_parse_error grpc_chttp2_data_parser_parse(
       p->frame_type = *cur;
       switch (p->frame_type) {
         case 0:
-          /* noop */
+          p->is_frame_compressed = 0;  /* GPR_FALSE */
           break;
         case 1:
-          gpr_log(GPR_ERROR, "Compressed GRPC frames not yet supported");
-          return GRPC_CHTTP2_STREAM_ERROR;
+          p->is_frame_compressed = 1;  /* GPR_TRUE */
+          break;
         default:
           gpr_log(GPR_ERROR, "Bad GRPC frame type 0x%02x", p->frame_type);
           return GRPC_CHTTP2_STREAM_ERROR;
@@ -130,7 +131,11 @@ grpc_chttp2_parse_error grpc_chttp2_data_parser_parse(
       p->frame_size |= ((gpr_uint32)*cur);
       p->state = GRPC_CHTTP2_DATA_FRAME;
       ++cur;
-      grpc_sopb_add_begin_message(&p->incoming_sopb, p->frame_size, 0);
+      if (p->is_frame_compressed) {
+        message_flags |= GRPC_WRITE_INTERNAL_COMPRESS;
+      }
+      grpc_sopb_add_begin_message(&p->incoming_sopb, p->frame_size,
+                                  message_flags);
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FRAME:
       if (cur == end) {
diff --git a/src/core/transport/chttp2/frame_data.h b/src/core/transport/chttp2/frame_data.h
index 8d6cfcb841..23957b05ad 100644
--- a/src/core/transport/chttp2/frame_data.h
+++ b/src/core/transport/chttp2/frame_data.h
@@ -56,6 +56,7 @@ typedef struct {
   gpr_uint8 frame_type;
   gpr_uint32 frame_size;
 
+  int is_frame_compressed;
   grpc_stream_op_buffer incoming_sopb;
 } grpc_chttp2_data_parser;
 
diff --git a/src/core/transport/chttp2/incoming_metadata.c b/src/core/transport/chttp2/incoming_metadata.c
index 77162a6864..974b864ffb 100644
--- a/src/core/transport/chttp2/incoming_metadata.c
+++ b/src/core/transport/chttp2/incoming_metadata.c
@@ -42,7 +42,7 @@
 
 void grpc_chttp2_incoming_metadata_buffer_init(
     grpc_chttp2_incoming_metadata_buffer *buffer) {
-  buffer->deadline = gpr_inf_future;
+  buffer->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 void grpc_chttp2_incoming_metadata_buffer_destroy(
@@ -87,7 +87,7 @@ void grpc_chttp2_incoming_metadata_buffer_place_metadata_batch_into(
   b.list.tail = (void *)(gpr_intptr)buffer->count;
   b.garbage.head = b.garbage.tail = NULL;
   b.deadline = buffer->deadline;
-  buffer->deadline = gpr_inf_future;
+  buffer->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 
   grpc_sopb_add_metadata(sopb, b);
 }
diff --git a/src/core/transport/chttp2/internal.h b/src/core/transport/chttp2/internal.h
index e5e6f445b7..74b3a591d5 100644
--- a/src/core/transport/chttp2/internal.h
+++ b/src/core/transport/chttp2/internal.h
@@ -60,7 +60,6 @@ typedef enum {
   GRPC_CHTTP2_LIST_WRITABLE,
   GRPC_CHTTP2_LIST_WRITING,
   GRPC_CHTTP2_LIST_WRITTEN,
-  GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE,
   GRPC_CHTTP2_LIST_PARSING_SEEN,
   GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_PARSING,
   GRPC_CHTTP2_LIST_CANCELLED_WAITING_FOR_WRITING,
@@ -286,6 +285,7 @@ struct grpc_chttp2_transport {
   grpc_endpoint *ep;
   grpc_mdctx *metadata_context;
   gpr_refcount refs;
+  char *peer_string;
 
   gpr_mu mu;
 
@@ -382,6 +382,10 @@ typedef struct {
   gpr_uint8 published_cancelled;
   /** is this stream in the stream map? (boolean) */
   gpr_uint8 in_stream_map;
+  /** is this stream actively being written? */
+  gpr_uint8 writing_now;
+  /** has anything been written to this stream? */
+  gpr_uint8 written_anything;
 
   /** stream state already published to the upper layer */
   grpc_stream_state published_state;
@@ -474,11 +478,17 @@ void grpc_chttp2_publish_reads(grpc_chttp2_transport_global *global,
 void grpc_chttp2_list_add_writable_stream(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global);
+void grpc_chttp2_list_add_first_writable_stream(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global);
 int grpc_chttp2_list_pop_writable_stream(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_transport_writing *transport_writing,
     grpc_chttp2_stream_global **stream_global,
     grpc_chttp2_stream_writing **stream_writing);
+void grpc_chttp2_list_remove_writable_stream(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global);
 
 void grpc_chttp2_list_add_incoming_window_updated(
     grpc_chttp2_transport_global *transport_global,
@@ -510,18 +520,6 @@ int grpc_chttp2_list_pop_written_stream(
     grpc_chttp2_stream_global **stream_global,
     grpc_chttp2_stream_writing **stream_writing);
 
-void grpc_chttp2_list_add_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing);
-void grpc_chttp2_list_remove_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-
 void grpc_chttp2_list_add_parsing_seen_stream(
     grpc_chttp2_transport_parsing *transport_parsing,
     grpc_chttp2_stream_parsing *stream_parsing);
diff --git a/src/core/transport/chttp2/parsing.c b/src/core/transport/chttp2/parsing.c
index 82362544d5..d84960009b 100644
--- a/src/core/transport/chttp2/parsing.c
+++ b/src/core/transport/chttp2/parsing.c
@@ -182,8 +182,7 @@ void grpc_chttp2_publish_reads(
       stream_global->max_recv_bytes -= 
           stream_parsing->incoming_window_delta;
       stream_parsing->incoming_window_delta = 0;
-      grpc_chttp2_list_add_writable_window_update_stream(transport_global,
-                                                         stream_global);
+      grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
     }
 
     /* update outgoing flow control window */
@@ -588,7 +587,7 @@ static void on_header(void *tp, grpc_mdelem *md) {
   GPR_ASSERT(stream_parsing);
 
   GRPC_CHTTP2_IF_TRACING(gpr_log(
-      GPR_INFO, "HTTP:%d:HDR: %s: %s", stream_parsing->id,
+      GPR_INFO, "HTTP:%d:HDR:%s: %s: %s", stream_parsing->id,
       transport_parsing->is_client ? "CLI" : "SVR",
       grpc_mdstr_as_c_string(md->key), grpc_mdstr_as_c_string(md->value)));
 
@@ -601,13 +600,13 @@ static void on_header(void *tp, grpc_mdelem *md) {
                                       cached_timeout)) {
         gpr_log(GPR_ERROR, "Ignoring bad timeout value '%s'",
                 grpc_mdstr_as_c_string(md->value));
-        *cached_timeout = gpr_inf_future;
+        *cached_timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
       }
       grpc_mdelem_set_user_data(md, free_timeout, cached_timeout);
     }
     grpc_chttp2_incoming_metadata_buffer_set_deadline(
         &stream_parsing->incoming_metadata,
-        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), *cached_timeout));
+        gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), *cached_timeout));
     GRPC_MDELEM_UNREF(md);
   } else {
     grpc_chttp2_incoming_metadata_buffer_add(&stream_parsing->incoming_metadata,
diff --git a/src/core/transport/chttp2/stream_encoder.c b/src/core/transport/chttp2/stream_encoder.c
index d553d80085..0f04169741 100644
--- a/src/core/transport/chttp2/stream_encoder.c
+++ b/src/core/transport/chttp2/stream_encoder.c
@@ -438,10 +438,10 @@ static void deadline_enc(grpc_chttp2_hpack_compressor *c, gpr_timespec deadline,
   char timeout_str[GRPC_CHTTP2_TIMEOUT_ENCODE_MIN_BUFSIZE];
   grpc_mdelem *mdelem;
   grpc_chttp2_encode_timeout(
-      gpr_time_sub(deadline, gpr_now(GPR_CLOCK_REALTIME)), timeout_str);
+      gpr_time_sub(deadline, gpr_now(deadline.clock_type)), timeout_str);
   mdelem = grpc_mdelem_from_metadata_strings(
       c->mdctx, GRPC_MDSTR_REF(c->timeout_key_str),
-      grpc_mdstr_from_string(c->mdctx, timeout_str));
+      grpc_mdstr_from_string(c->mdctx, timeout_str, 0));
   mdelem = hpack_enc(c, mdelem, st);
   if (mdelem) GRPC_MDELEM_UNREF(mdelem);
 }
@@ -456,7 +456,7 @@ void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c,
                                        grpc_mdctx *ctx) {
   memset(c, 0, sizeof(*c));
   c->mdctx = ctx;
-  c->timeout_key_str = grpc_mdstr_from_string(ctx, "grpc-timeout");
+  c->timeout_key_str = grpc_mdstr_from_string(ctx, "grpc-timeout", 0);
 }
 
 void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c) {
@@ -477,6 +477,7 @@ gpr_uint32 grpc_chttp2_preencode(grpc_stream_op *inops, size_t *inops_count,
   gpr_uint32 flow_controlled_bytes_taken = 0;
   gpr_uint32 curop = 0;
   gpr_uint8 *p;
+  int compressed_flag_set = 0;
 
   while (curop < *inops_count) {
     GPR_ASSERT(flow_controlled_bytes_taken <= max_flow_controlled_bytes);
@@ -496,9 +497,12 @@ gpr_uint32 grpc_chttp2_preencode(grpc_stream_op *inops, size_t *inops_count,
       case GRPC_OP_BEGIN_MESSAGE:
         /* begin op: for now we just convert the op to a slice and fall
            through - this lets us reuse the slice framing code below */
+        compressed_flag_set =
+            (op->data.begin_message.flags & GRPC_WRITE_INTERNAL_COMPRESS) != 0;
         slice = gpr_slice_malloc(5);
+
         p = GPR_SLICE_START_PTR(slice);
-        p[0] = 0;
+        p[0] = compressed_flag_set;
         p[1] = op->data.begin_message.length >> 24;
         p[2] = op->data.begin_message.length >> 16;
         p[3] = op->data.begin_message.length >> 8;
@@ -556,6 +560,7 @@ void grpc_chttp2_encode(grpc_stream_op *ops, size_t ops_count, int eof,
   grpc_mdctx *mdctx = compressor->mdctx;
   grpc_linked_mdelem *l;
   int need_unref = 0;
+  gpr_timespec deadline;
 
   GPR_ASSERT(stream_id != 0);
 
@@ -585,8 +590,9 @@ void grpc_chttp2_encode(grpc_stream_op *ops, size_t ops_count, int eof,
           l->md = hpack_enc(compressor, l->md, &st);
           need_unref |= l->md != NULL;
         }
-        if (gpr_time_cmp(op->data.metadata.deadline, gpr_inf_future) != 0) {
-          deadline_enc(compressor, op->data.metadata.deadline, &st);
+        deadline = op->data.metadata.deadline;
+        if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) != 0) {
+          deadline_enc(compressor, deadline, &st);
         }
         curop++;
         break;
diff --git a/src/core/transport/chttp2/stream_lists.c b/src/core/transport/chttp2/stream_lists.c
index 590f6abfbc..9e68c1e146 100644
--- a/src/core/transport/chttp2/stream_lists.c
+++ b/src/core/transport/chttp2/stream_lists.c
@@ -108,6 +108,23 @@ static void stream_list_maybe_remove(grpc_chttp2_transport *t,
   }
 }
 
+static void stream_list_add_head(grpc_chttp2_transport *t,
+                                 grpc_chttp2_stream *s,
+                                 grpc_chttp2_stream_list_id id) {
+  grpc_chttp2_stream *old_head;
+  GPR_ASSERT(!s->included[id]);
+  old_head = t->lists[id].head;
+  s->links[id].next = old_head;
+  s->links[id].prev = NULL;
+  if (old_head) {
+    old_head->links[id].prev = s;
+  } else {
+    t->lists[id].tail = s;
+  }
+  t->lists[id].head = s;
+  s->included[id] = 1;
+}
+
 static void stream_list_add_tail(grpc_chttp2_transport *t,
                                  grpc_chttp2_stream *s,
                                  grpc_chttp2_stream_list_id id) {
@@ -119,7 +136,6 @@ static void stream_list_add_tail(grpc_chttp2_transport *t,
   if (old_tail) {
     old_tail->links[id].next = s;
   } else {
-    s->links[id].prev = NULL;
     t->lists[id].head = s;
   }
   t->lists[id].tail = s;
@@ -144,6 +160,18 @@ void grpc_chttp2_list_add_writable_stream(
                   STREAM_FROM_GLOBAL(stream_global), GRPC_CHTTP2_LIST_WRITABLE);
 }
 
+void grpc_chttp2_list_add_first_writable_stream(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global) {
+  GPR_ASSERT(stream_global->id != 0);
+  gpr_log(GPR_DEBUG, "add:%d:%d:%d:%d", stream_global->id,
+          stream_global->write_state, stream_global->in_stream_map,
+          stream_global->read_closed);
+  stream_list_add_head(TRANSPORT_FROM_GLOBAL(transport_global),
+                       STREAM_FROM_GLOBAL(stream_global),
+                       GRPC_CHTTP2_LIST_WRITABLE);
+}
+
 int grpc_chttp2_list_pop_writable_stream(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_transport_writing *transport_writing,
@@ -157,6 +185,14 @@ int grpc_chttp2_list_pop_writable_stream(
   return r;
 }
 
+void grpc_chttp2_list_remove_writable_stream(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global) {
+  stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
+                           STREAM_FROM_GLOBAL(stream_global),
+                           GRPC_CHTTP2_LIST_WRITABLE);
+}
+
 void grpc_chttp2_list_add_writing_stream(
     grpc_chttp2_transport_writing *transport_writing,
     grpc_chttp2_stream_writing *stream_writing) {
@@ -202,36 +238,6 @@ int grpc_chttp2_list_pop_written_stream(
   return r;
 }
 
-void grpc_chttp2_list_add_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  GPR_ASSERT(stream_global->id != 0);
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE);
-}
-
-int grpc_chttp2_list_pop_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE);
-  *stream_global = &stream->global;
-  *stream_writing = &stream->writing;
-  return r;
-}
-
-void grpc_chttp2_list_remove_writable_window_update_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
-                           STREAM_FROM_GLOBAL(stream_global),
-                           GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE);
-}
-
 void grpc_chttp2_list_add_parsing_seen_stream(
     grpc_chttp2_transport_parsing *transport_parsing,
     grpc_chttp2_stream_parsing *stream_parsing) {
diff --git a/src/core/transport/chttp2/timeout_encoding.c b/src/core/transport/chttp2/timeout_encoding.c
index 33915c4039..1dd768ada4 100644
--- a/src/core/transport/chttp2/timeout_encoding.c
+++ b/src/core/transport/chttp2/timeout_encoding.c
@@ -147,7 +147,7 @@ int grpc_chttp2_decode_timeout(const char *buffer, gpr_timespec *timeout) {
     gpr_uint32 xp = x * 10 + *p - '0';
     have_digit = 1;
     if (xp < x) {
-      *timeout = gpr_inf_future;
+      *timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
       return 1;
     }
     x = xp;
@@ -159,22 +159,22 @@ int grpc_chttp2_decode_timeout(const char *buffer, gpr_timespec *timeout) {
   /* decode unit specifier */
   switch (*p) {
     case 'n':
-      *timeout = gpr_time_from_nanos(x);
+      *timeout = gpr_time_from_nanos(x, GPR_TIMESPAN);
       break;
     case 'u':
-      *timeout = gpr_time_from_micros(x);
+      *timeout = gpr_time_from_micros(x, GPR_TIMESPAN);
       break;
     case 'm':
-      *timeout = gpr_time_from_millis(x);
+      *timeout = gpr_time_from_millis(x, GPR_TIMESPAN);
       break;
     case 'S':
-      *timeout = gpr_time_from_seconds(x);
+      *timeout = gpr_time_from_seconds(x, GPR_TIMESPAN);
       break;
     case 'M':
-      *timeout = gpr_time_from_minutes(x);
+      *timeout = gpr_time_from_minutes(x, GPR_TIMESPAN);
       break;
     case 'H':
-      *timeout = gpr_time_from_hours(x);
+      *timeout = gpr_time_from_hours(x, GPR_TIMESPAN);
       break;
     default:
       return 0;
diff --git a/src/core/transport/chttp2/writing.c b/src/core/transport/chttp2/writing.c
index d8ec117aa5..d39b0c42f7 100644
--- a/src/core/transport/chttp2/writing.c
+++ b/src/core/transport/chttp2/writing.c
@@ -44,6 +44,7 @@ int grpc_chttp2_unlocking_check_writes(
     grpc_chttp2_transport_writing *transport_writing) {
   grpc_chttp2_stream_global *stream_global;
   grpc_chttp2_stream_writing *stream_writing;
+  grpc_chttp2_stream_global *first_reinserted_stream = NULL;
   gpr_uint32 window_delta;
 
   /* simple writes are queued to qbuf, and flushed here */
@@ -64,50 +65,54 @@ int grpc_chttp2_unlocking_check_writes(
   }
 
   /* for each grpc_chttp2_stream that's become writable, frame it's data
-     (according to
-     available window sizes) and add to the output buffer */
-  while (grpc_chttp2_list_pop_writable_stream(transport_global,
-                                              transport_writing, &stream_global,
-                                              &stream_writing)) {
+     (according to available window sizes) and add to the output buffer */
+  while (grpc_chttp2_list_pop_writable_stream(
+      transport_global, transport_writing, &stream_global, &stream_writing)) {
+    if (stream_global == first_reinserted_stream) {
+      /* prevent infinite loop */
+      grpc_chttp2_list_add_first_writable_stream(transport_global,
+                                                 stream_global);
+      break;
+    }
+
     stream_writing->id = stream_global->id;
-    window_delta = grpc_chttp2_preencode(
-        stream_global->outgoing_sopb->ops, &stream_global->outgoing_sopb->nops,
-        GPR_MIN(transport_global->outgoing_window,
-                stream_global->outgoing_window),
-        &stream_writing->sopb);
-    GRPC_CHTTP2_FLOWCTL_TRACE_TRANSPORT(
-        "write", transport_global, outgoing_window, -(gpr_int64)window_delta);
-    GRPC_CHTTP2_FLOWCTL_TRACE_STREAM("write", transport_global, stream_global,
-                                     outgoing_window, -(gpr_int64)window_delta);
-    transport_global->outgoing_window -= window_delta;
-    stream_global->outgoing_window -= window_delta;
-
-    if (stream_global->write_state == GRPC_WRITE_STATE_QUEUED_CLOSE &&
-        stream_global->outgoing_sopb->nops == 0) {
-      if (!transport_global->is_client && !stream_global->read_closed) {
-        stream_writing->send_closed = GRPC_SEND_CLOSED_WITH_RST_STREAM;
-      } else {
-        stream_writing->send_closed = GRPC_SEND_CLOSED;
+    stream_writing->send_closed = GRPC_DONT_SEND_CLOSED;
+    GPR_ASSERT(!stream_global->writing_now);
+
+    if (stream_global->outgoing_sopb) {
+      window_delta =
+          grpc_chttp2_preencode(stream_global->outgoing_sopb->ops,
+                                &stream_global->outgoing_sopb->nops,
+                                GPR_MIN(transport_global->outgoing_window,
+                                        stream_global->outgoing_window),
+                                &stream_writing->sopb);
+      GRPC_CHTTP2_FLOWCTL_TRACE_TRANSPORT(
+          "write", transport_global, outgoing_window, -(gpr_int64)window_delta);
+      GRPC_CHTTP2_FLOWCTL_TRACE_STREAM("write", transport_global, stream_global,
+                                       outgoing_window,
+                                       -(gpr_int64)window_delta);
+      transport_global->outgoing_window -= window_delta;
+      stream_global->outgoing_window -= window_delta;
+
+      if (stream_global->write_state == GRPC_WRITE_STATE_QUEUED_CLOSE &&
+          stream_global->outgoing_sopb->nops == 0) {
+        if (!transport_global->is_client && !stream_global->read_closed) {
+          stream_writing->send_closed = GRPC_SEND_CLOSED_WITH_RST_STREAM;
+        } else {
+          stream_writing->send_closed = GRPC_SEND_CLOSED;
+        }
       }
-    }
-    if (stream_writing->sopb.nops > 0 ||
-        stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
-      grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
-    }
 
-    if (stream_global->outgoing_window > 0 &&
-        stream_global->outgoing_sopb->nops != 0) {
-      grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
+      if (stream_global->outgoing_window > 0 &&
+          stream_global->outgoing_sopb->nops != 0) {
+        grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
+        if (first_reinserted_stream == NULL &&
+            transport_global->outgoing_window == 0) {
+          first_reinserted_stream = stream_global;
+        }
+      }
     }
-  }
 
-  /* for each grpc_chttp2_stream that wants to update its window, add that
-   * window here */
-  while (grpc_chttp2_list_pop_writable_window_update_stream(transport_global,
-                                                            transport_writing,
-                                                            &stream_global,
-                                                            &stream_writing)) {
-    stream_writing->id = stream_global->id;
     if (!stream_global->read_closed && stream_global->unannounced_incoming_window > 0) {
       stream_writing->announce_window = stream_global->unannounced_incoming_window;
       GRPC_CHTTP2_FLOWCTL_TRACE_STREAM("write", transport_global, stream_global,
@@ -118,6 +123,11 @@ int grpc_chttp2_unlocking_check_writes(
       stream_global->unannounced_incoming_window = 0;
       grpc_chttp2_list_add_incoming_window_updated(transport_global,
                                                    stream_global);
+      stream_global->writing_now = 1;
+      grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
+    } else if (stream_writing->sopb.nops > 0 ||
+               stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
+      stream_global->writing_now = 1;
       grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
     }
   }
@@ -205,6 +215,8 @@ void grpc_chttp2_cleanup_writing(
 
   while (grpc_chttp2_list_pop_written_stream(
       transport_global, transport_writing, &stream_global, &stream_writing)) {
+    GPR_ASSERT(stream_global->writing_now);
+    stream_global->writing_now = 0;
     if (stream_global->outgoing_sopb != NULL &&
         stream_global->outgoing_sopb->nops == 0) {
       stream_global->outgoing_sopb = NULL;
@@ -216,9 +228,9 @@ void grpc_chttp2_cleanup_writing(
       if (!transport_global->is_client) {
         stream_global->read_closed = 1;
       }
-      grpc_chttp2_list_add_read_write_state_changed(transport_global,
-                                                    stream_global);
     }
+    grpc_chttp2_list_add_read_write_state_changed(transport_global,
+                                                  stream_global);
   }
   transport_writing->outbuf.count = 0;
   transport_writing->outbuf.length = 0;
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index c923d5e42f..c8c4207208 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -107,9 +107,16 @@ static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
                             grpc_chttp2_stream_global *stream_global,
                             grpc_status_code status);
 
+static void close_from_api(grpc_chttp2_transport_global *transport_global,
+                           grpc_chttp2_stream_global *stream_global,
+                           grpc_status_code status,
+                           gpr_slice *optional_message);
+
 /** Add endpoint from this transport to pollset */
 static void add_to_pollset_locked(grpc_chttp2_transport *t,
                                   grpc_pollset *pollset);
+static void add_to_pollset_set_locked(grpc_chttp2_transport *t,
+                                  grpc_pollset_set *pollset_set);
 
 /** Start new streams that have been created if we can */
 static void maybe_start_some_streams(
@@ -117,7 +124,7 @@ static void maybe_start_some_streams(
 
 static void connectivity_state_set(
     grpc_chttp2_transport_global *transport_global,
-    grpc_connectivity_state state);
+    grpc_connectivity_state state, const char *reason);
 
 /*
  * CONSTRUCTION/DESTRUCTION/REFCOUNTING
@@ -168,6 +175,7 @@ static void destruct_transport(grpc_chttp2_transport *t) {
 
   grpc_mdctx_unref(t->metadata_context);
 
+  gpr_free(t->peer_string);
   gpr_free(t);
 }
 
@@ -217,6 +225,7 @@ static void init_transport(grpc_chttp2_transport *t,
   gpr_ref_init(&t->refs, 2);
   gpr_mu_init(&t->mu);
   grpc_mdctx_ref(mdctx);
+  t->peer_string = grpc_endpoint_get_peer(ep);
   t->metadata_context = mdctx;
   t->endpoint_reading = 1;
   t->global.next_stream_id = is_client ? 1 : 2;
@@ -228,12 +237,12 @@ static void init_transport(grpc_chttp2_transport *t,
   t->global.pings.next = t->global.pings.prev = &t->global.pings;
   t->parsing.is_client = is_client;
   t->parsing.str_grpc_timeout =
-      grpc_mdstr_from_string(t->metadata_context, "grpc-timeout");
+      grpc_mdstr_from_string(t->metadata_context, "grpc-timeout", 0);
   t->parsing.deframe_state =
       is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0;
   t->writing.is_client = is_client;
   grpc_connectivity_state_init(&t->channel_callback.state_tracker,
-                               GRPC_CHANNEL_READY);
+                               GRPC_CHANNEL_READY, "transport");
 
   gpr_slice_buffer_init(&t->global.qbuf);
 
@@ -327,7 +336,8 @@ static void destroy_transport(grpc_transport *gt) {
 static void close_transport_locked(grpc_chttp2_transport *t) {
   if (!t->closed) {
     t->closed = 1;
-    connectivity_state_set(&t->global, GRPC_CHANNEL_FATAL_FAILURE);
+    connectivity_state_set(&t->global, GRPC_CHANNEL_FATAL_FAILURE,
+                           "close_transport");
     if (t->ep) {
       grpc_endpoint_shutdown(t->ep);
     }
@@ -393,12 +403,16 @@ static void destroy_stream(grpc_transport *gt, grpc_stream *gs) {
   }
 
   grpc_chttp2_list_remove_incoming_window_updated(&t->global, &s->global);
-  grpc_chttp2_list_remove_writable_window_update_stream(&t->global, &s->global);
+  grpc_chttp2_list_remove_writable_stream(&t->global, &s->global);
 
   gpr_mu_unlock(&t->mu);
 
   for (i = 0; i < STREAM_LIST_COUNT; i++) {
-    GPR_ASSERT(!s->included[i]);
+    if (s->included[i]) {
+      gpr_log(GPR_ERROR, "%s stream %d still included in list %d",
+              t->global.is_client ? "client" : "server", s->global.id, i);
+      abort();
+    }
   }
 
   GPR_ASSERT(s->global.outgoing_sopb == NULL);
@@ -530,7 +544,8 @@ void grpc_chttp2_add_incoming_goaway(
   gpr_free(msg);
   gpr_slice_unref(goaway_text);
   transport_global->seen_goaway = 1;
-  connectivity_state_set(transport_global, GRPC_CHANNEL_FATAL_FAILURE);
+  connectivity_state_set(transport_global, GRPC_CHANNEL_FATAL_FAILURE,
+                         "got_goaway");
 }
 
 static void maybe_start_some_streams(
@@ -555,7 +570,8 @@ static void maybe_start_some_streams(
     transport_global->next_stream_id += 2;
 
     if (transport_global->next_stream_id >= MAX_CLIENT_STREAM_ID) {
-      connectivity_state_set(transport_global, GRPC_CHANNEL_TRANSIENT_FAILURE);
+      connectivity_state_set(transport_global, GRPC_CHANNEL_TRANSIENT_FAILURE,
+                             "no_more_stream_ids");
     }
 
     stream_global->outgoing_window =
@@ -574,8 +590,6 @@ static void maybe_start_some_streams(
     grpc_chttp2_list_add_incoming_window_updated(transport_global,
                                                  stream_global);
     grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
-    grpc_chttp2_list_add_writable_window_update_stream(transport_global,
-                                                       stream_global);
 
   }
   /* cancel out streams that will never be started */
@@ -593,10 +607,16 @@ static void perform_stream_op_locked(
     cancel_from_api(transport_global, stream_global, op->cancel_with_status);
   }
 
+  if (op->close_with_status != GRPC_STATUS_OK) {
+    close_from_api(transport_global, stream_global, op->close_with_status,
+                   op->optional_close_message);
+  }
+
   if (op->send_ops) {
     GPR_ASSERT(stream_global->outgoing_sopb == NULL);
     stream_global->send_done_closure = op->on_done_send;
     if (!stream_global->cancelled) {
+      stream_global->written_anything = 1;
       stream_global->outgoing_sopb = op->send_ops;
       if (op->is_last_send &&
           stream_global->write_state == GRPC_WRITE_STATE_OPEN) {
@@ -641,8 +661,7 @@ static void perform_stream_op_locked(
     if (stream_global->id != 0) {
       grpc_chttp2_list_add_read_write_state_changed(transport_global,
                                                     stream_global);
-      grpc_chttp2_list_add_writable_window_update_stream(transport_global,
-                                                         stream_global);
+      grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
     }
   }
 
@@ -686,6 +705,7 @@ static void send_ping_locked(grpc_chttp2_transport *t,
 
 static void perform_transport_op(grpc_transport *gt, grpc_transport_op *op) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
+  int close_transport = 0;
 
   lock(t);
 
@@ -705,9 +725,7 @@ static void perform_transport_op(grpc_transport *gt, grpc_transport_op *op) {
         t->global.last_incoming_stream_id,
         grpc_chttp2_grpc_status_to_http2_error(op->goaway_status),
         gpr_slice_ref(*op->goaway_message), &t->global.qbuf);
-    if (!grpc_chttp2_has_streams(t)) {
-      close_transport_locked(t);
-    }
+    close_transport = !grpc_chttp2_has_streams(t);
   }
 
   if (op->set_accept_stream != NULL) {
@@ -720,6 +738,10 @@ static void perform_transport_op(grpc_transport *gt, grpc_transport_op *op) {
     add_to_pollset_locked(t, op->bind_pollset);
   }
 
+  if (op->bind_pollset_set) {
+    add_to_pollset_set_locked(t, op->bind_pollset_set);
+  }
+
   if (op->send_ping) {
     send_ping_locked(t, op->send_ping);
   }
@@ -729,6 +751,12 @@ static void perform_transport_op(grpc_transport *gt, grpc_transport_op *op) {
   }
 
   unlock(t);
+
+  if (close_transport) {
+    lock(t);
+    close_transport_locked(t);
+    unlock(t);
+  }
 }
 
 /*
@@ -750,6 +778,7 @@ static void remove_stream(grpc_chttp2_transport *t, gpr_uint32 id) {
   if (!s) {
     s = grpc_chttp2_stream_map_delete(&t->new_stream_map, id);
   }
+  grpc_chttp2_list_remove_writable_stream(&t->global, &s->global);
   GPR_ASSERT(s);
   s->global.in_stream_map = 0;
   if (t->parsing.incoming_stream == &s->parsing) {
@@ -831,6 +860,9 @@ static void unlock_check_read_write_state(grpc_chttp2_transport *t) {
     if (!stream_global->publish_sopb) {
       continue;
     }
+    if (stream_global->writing_now) {
+      continue;
+    }
     /* FIXME(ctiller): we include in_stream_map in our computation of
        whether the stream is write-closed. This is completely bogus,
        but has the effect of delaying stream-closed until the stream
@@ -873,6 +905,108 @@ static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
                                                 stream_global);
 }
 
+static void close_from_api(grpc_chttp2_transport_global *transport_global,
+                           grpc_chttp2_stream_global *stream_global,
+                           grpc_status_code status,
+                           gpr_slice *optional_message) {
+  gpr_slice hdr;
+  gpr_slice status_hdr;
+  gpr_slice message_pfx;
+  gpr_uint8 *p;
+  gpr_uint32 len = 0;
+
+  GPR_ASSERT(status >= 0 && (int)status < 100);
+
+  stream_global->cancelled = 1;
+  stream_global->cancelled_status = status;
+  GPR_ASSERT(stream_global->id != 0);
+  GPR_ASSERT(!stream_global->written_anything);
+
+  /* Hand roll a header block.
+     This is unnecessarily ugly - at some point we should find a more elegant
+     solution.
+     It's complicated by the fact that our send machinery would be dead by the
+     time we got around to sending this, so instead we ignore HPACK compression
+     and just write the uncompressed bytes onto the wire. */
+  status_hdr = gpr_slice_malloc(15 + (status >= 10));
+  p = GPR_SLICE_START_PTR(status_hdr);
+  *p++ = 0x40; /* literal header */
+  *p++ = 11;   /* len(grpc-status) */
+  *p++ = 'g';
+  *p++ = 'r';
+  *p++ = 'p';
+  *p++ = 'c';
+  *p++ = '-';
+  *p++ = 's';
+  *p++ = 't';
+  *p++ = 'a';
+  *p++ = 't';
+  *p++ = 'u';
+  *p++ = 's';
+  if (status < 10) {
+    *p++ = 1;
+    *p++ = '0' + status;
+  } else {
+    *p++ = 2;
+    *p++ = '0' + (status / 10);
+    *p++ = '0' + (status % 10);
+  }
+  GPR_ASSERT(p == GPR_SLICE_END_PTR(status_hdr));
+  len += GPR_SLICE_LENGTH(status_hdr);
+
+  if (optional_message) {
+    GPR_ASSERT(GPR_SLICE_LENGTH(*optional_message) < 127);
+    message_pfx = gpr_slice_malloc(15);
+    p = GPR_SLICE_START_PTR(message_pfx);
+    *p++ = 0x40;
+    *p++ = 12; /* len(grpc-message) */
+    *p++ = 'g';
+    *p++ = 'r';
+    *p++ = 'p';
+    *p++ = 'c';
+    *p++ = '-';
+    *p++ = 'm';
+    *p++ = 'e';
+    *p++ = 's';
+    *p++ = 's';
+    *p++ = 'a';
+    *p++ = 'g';
+    *p++ = 'e';
+    *p++ = GPR_SLICE_LENGTH(*optional_message);
+    GPR_ASSERT(p == GPR_SLICE_END_PTR(message_pfx));
+    len += GPR_SLICE_LENGTH(message_pfx);
+    len += GPR_SLICE_LENGTH(*optional_message);
+  }
+
+  hdr = gpr_slice_malloc(9);
+  p = GPR_SLICE_START_PTR(hdr);
+  *p++ = len >> 16;
+  *p++ = len >> 8;
+  *p++ = len;
+  *p++ = GRPC_CHTTP2_FRAME_HEADER;
+  *p++ = GRPC_CHTTP2_DATA_FLAG_END_STREAM | GRPC_CHTTP2_DATA_FLAG_END_HEADERS;
+  *p++ = stream_global->id >> 24;
+  *p++ = stream_global->id >> 16;
+  *p++ = stream_global->id >> 8;
+  *p++ = stream_global->id;
+  GPR_ASSERT(p == GPR_SLICE_END_PTR(hdr));
+
+  gpr_slice_buffer_add(&transport_global->qbuf, hdr);
+  gpr_slice_buffer_add(&transport_global->qbuf, status_hdr);
+  if (optional_message) {
+    gpr_slice_buffer_add(&transport_global->qbuf, message_pfx);
+    gpr_slice_buffer_add(&transport_global->qbuf,
+                         gpr_slice_ref(*optional_message));
+  }
+
+  gpr_slice_buffer_add(
+      &transport_global->qbuf,
+      grpc_chttp2_rst_stream_create(stream_global->id, GRPC_CHTTP2_NO_ERROR));
+
+  grpc_chttp2_list_add_read_write_state_changed(transport_global,
+                                                stream_global);
+}
+
 static void cancel_stream_cb(grpc_chttp2_transport_global *transport_global,
                              void *user_data,
                              grpc_chttp2_stream_global *stream_global) {
@@ -1001,12 +1135,12 @@ static void schedule_closure_for_connectivity(void *a,
 
 static void connectivity_state_set(
     grpc_chttp2_transport_global *transport_global,
-    grpc_connectivity_state state) {
+    grpc_connectivity_state state, const char *reason) {
   GRPC_CHTTP2_IF_TRACING(
       gpr_log(GPR_DEBUG, "set connectivity_state=%d", state));
   grpc_connectivity_state_set_with_scheduler(
       &TRANSPORT_FROM_GLOBAL(transport_global)->channel_callback.state_tracker,
-      state, schedule_closure_for_connectivity, transport_global);
+      state, schedule_closure_for_connectivity, transport_global, reason);
 }
 
 void grpc_chttp2_schedule_closure(
@@ -1034,6 +1168,13 @@ static void add_to_pollset_locked(grpc_chttp2_transport *t,
   }
 }
 
+static void add_to_pollset_set_locked(grpc_chttp2_transport *t,
+                                  grpc_pollset_set *pollset_set) {
+  if (t->ep) {
+    grpc_endpoint_add_to_pollset_set(t->ep, pollset_set);
+  }
+}
+
 /*
  * TRACING
  */
@@ -1069,9 +1210,17 @@ void grpc_chttp2_flowctl_trace(const char *file, int line, const char *reason,
  * INTEGRATION GLUE
  */
 
-static const grpc_transport_vtable vtable = {
-    sizeof(grpc_chttp2_stream), init_stream,    perform_stream_op,
-    perform_transport_op,       destroy_stream, destroy_transport};
+static char *chttp2_get_peer(grpc_transport *t) {
+  return gpr_strdup(((grpc_chttp2_transport *)t)->peer_string);
+}
+
+static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
+                                             init_stream,
+                                             perform_stream_op,
+                                             perform_transport_op,
+                                             destroy_stream,
+                                             destroy_transport,
+                                             chttp2_get_peer};
 
 grpc_transport *grpc_create_chttp2_transport(
     const grpc_channel_args *channel_args, grpc_endpoint *ep, grpc_mdctx *mdctx,
diff --git a/src/core/transport/connectivity_state.c b/src/core/transport/connectivity_state.c
index 1091ceae44..61d26f06f0 100644
--- a/src/core/transport/connectivity_state.c
+++ b/src/core/transport/connectivity_state.c
@@ -34,11 +34,33 @@
 #include "src/core/transport/connectivity_state.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+int grpc_connectivity_state_trace = 0;
+
+const char *grpc_connectivity_state_name(grpc_connectivity_state state) {
+  switch (state) {
+    case GRPC_CHANNEL_IDLE:
+      return "IDLE";
+    case GRPC_CHANNEL_CONNECTING:
+      return "CONNECTING";
+    case GRPC_CHANNEL_READY:
+      return "READY";
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+      return "TRANSIENT_FAILURE";
+    case GRPC_CHANNEL_FATAL_FAILURE:
+      return "FATAL_FAILURE";
+  }
+  abort();
+  return "UNKNOWN";
+}
 
 void grpc_connectivity_state_init(grpc_connectivity_state_tracker *tracker,
-                                  grpc_connectivity_state init_state) {
+                                  grpc_connectivity_state init_state,
+                                  const char *name) {
   tracker->current_state = init_state;
   tracker->watchers = NULL;
+  tracker->name = gpr_strdup(name);
 }
 
 void grpc_connectivity_state_destroy(grpc_connectivity_state_tracker *tracker) {
@@ -54,6 +76,7 @@ void grpc_connectivity_state_destroy(grpc_connectivity_state_tracker *tracker) {
     }
     gpr_free(w);
   }
+  gpr_free(tracker->name);
 }
 
 grpc_connectivity_state grpc_connectivity_state_check(
@@ -64,6 +87,11 @@ grpc_connectivity_state grpc_connectivity_state_check(
 int grpc_connectivity_state_notify_on_state_change(
     grpc_connectivity_state_tracker *tracker, grpc_connectivity_state *current,
     grpc_iomgr_closure *notify) {
+  if (grpc_connectivity_state_trace) {
+    gpr_log(GPR_DEBUG, "CONWATCH: %s: from %s [cur=%s]", tracker->name,
+            grpc_connectivity_state_name(*current),
+            grpc_connectivity_state_name(tracker->current_state));
+  }
   if (tracker->current_state != *current) {
     *current = tracker->current_state;
     grpc_iomgr_add_callback(notify);
@@ -79,12 +107,19 @@ int grpc_connectivity_state_notify_on_state_change(
 
 void grpc_connectivity_state_set_with_scheduler(
     grpc_connectivity_state_tracker *tracker, grpc_connectivity_state state,
-    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg) {
+    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg,
+    const char *reason) {
   grpc_connectivity_state_watcher *new = NULL;
   grpc_connectivity_state_watcher *w;
+  if (grpc_connectivity_state_trace) {
+    gpr_log(GPR_DEBUG, "SET: %s: %s --> %s [%s]", tracker->name,
+            grpc_connectivity_state_name(tracker->current_state),
+            grpc_connectivity_state_name(state), reason);
+  }
   if (tracker->current_state == state) {
     return;
   }
+  GPR_ASSERT(tracker->current_state != GRPC_CHANNEL_FATAL_FAILURE);
   tracker->current_state = state;
   while ((w = tracker->watchers)) {
     tracker->watchers = w->next;
@@ -106,7 +141,8 @@ static void default_scheduler(void *ignored, grpc_iomgr_closure *closure) {
 }
 
 void grpc_connectivity_state_set(grpc_connectivity_state_tracker *tracker,
-                                 grpc_connectivity_state state) {
+                                 grpc_connectivity_state state,
+                                 const char *reason) {
   grpc_connectivity_state_set_with_scheduler(tracker, state, default_scheduler,
-                                             NULL);
+                                             NULL, reason);
 }
diff --git a/src/core/transport/connectivity_state.h b/src/core/transport/connectivity_state.h
index bbdcbcb069..a3b0b80c98 100644
--- a/src/core/transport/connectivity_state.h
+++ b/src/core/transport/connectivity_state.h
@@ -51,17 +51,24 @@ typedef struct {
   grpc_connectivity_state current_state;
   /** all our watchers */
   grpc_connectivity_state_watcher *watchers;
+  /** a name to help debugging */
+  char *name;
 } grpc_connectivity_state_tracker;
 
+extern int grpc_connectivity_state_trace;
+
 void grpc_connectivity_state_init(grpc_connectivity_state_tracker *tracker,
-                                  grpc_connectivity_state init_state);
+                                  grpc_connectivity_state init_state,
+                                  const char *name);
 void grpc_connectivity_state_destroy(grpc_connectivity_state_tracker *tracker);
 
 void grpc_connectivity_state_set(grpc_connectivity_state_tracker *tracker,
-                                 grpc_connectivity_state state);
+                                 grpc_connectivity_state state,
+                                 const char *reason);
 void grpc_connectivity_state_set_with_scheduler(
     grpc_connectivity_state_tracker *tracker, grpc_connectivity_state state,
-    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg);
+    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg,
+    const char *reason);
 
 grpc_connectivity_state grpc_connectivity_state_check(
     grpc_connectivity_state_tracker *tracker);
diff --git a/src/core/transport/metadata.c b/src/core/transport/metadata.c
index e95b7a21f9..44d32b6cb2 100644
--- a/src/core/transport/metadata.c
+++ b/src/core/transport/metadata.c
@@ -135,7 +135,9 @@ static void unlock(grpc_mdctx *ctx) {
   if (ctx->refs == 0) {
     /* uncomment if you're having trouble diagnosing an mdelem leak to make
        things clearer (slows down destruction a lot, however) */
+#ifdef GRPC_METADATA_REFCOUNT_DEBUG
     gc_mdtab(ctx);
+#endif
     if (ctx->mdtab_count && ctx->mdtab_count == ctx->mdtab_free) {
       discard_metadata(ctx);
     }
@@ -309,7 +311,37 @@ static void slice_unref(void *p) {
   unlock(ctx);
 }
 
-grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str) {
+grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str, int canonicalize_key) {
+  if (canonicalize_key) {
+    size_t len;
+    size_t i;
+    int canonical = 1;
+
+    for (i = 0; str[i]; i++) {
+      if (str[i] >= 'A' && str[i] <= 'Z') {
+        canonical = 0;
+        /* Keep going in loop just to get string length */
+      }
+    }
+    len = i;
+
+    if (canonical) {
+      return grpc_mdstr_from_buffer(ctx, (const gpr_uint8 *)str, len);
+    } else {
+      char *copy = gpr_malloc(len);
+      grpc_mdstr *ret;
+      for (i = 0; i < len; i++) {
+        if (str[i] >= 'A' && str[i] <= 'Z') {
+          copy[i] = str[i] - 'A' + 'a';
+        } else {
+          copy[i] = str[i];
+        }
+      }
+      ret = grpc_mdstr_from_buffer(ctx, (const gpr_uint8 *)copy, len);
+      gpr_free(copy);
+      return ret;
+    }
+  }
   return grpc_mdstr_from_buffer(ctx, (const gpr_uint8 *)str, strlen(str));
 }
 
@@ -491,8 +523,8 @@ grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdctx *ctx,
 grpc_mdelem *grpc_mdelem_from_strings(grpc_mdctx *ctx, const char *key,
                                       const char *value) {
   return grpc_mdelem_from_metadata_strings(ctx,
-                                           grpc_mdstr_from_string(ctx, key),
-                                           grpc_mdstr_from_string(ctx, value));
+                                           grpc_mdstr_from_string(ctx, key, 0),
+                                           grpc_mdstr_from_string(ctx, value, 0));
 }
 
 grpc_mdelem *grpc_mdelem_from_slices(grpc_mdctx *ctx, gpr_slice key,
@@ -504,9 +536,10 @@ grpc_mdelem *grpc_mdelem_from_slices(grpc_mdctx *ctx, gpr_slice key,
 grpc_mdelem *grpc_mdelem_from_string_and_buffer(grpc_mdctx *ctx,
                                                 const char *key,
                                                 const gpr_uint8 *value,
-                                                size_t value_length) {
+                                                size_t value_length,
+                                                int canonicalize_key) {
   return grpc_mdelem_from_metadata_strings(
-      ctx, grpc_mdstr_from_string(ctx, key),
+      ctx, grpc_mdstr_from_string(ctx, key, canonicalize_key),
       grpc_mdstr_from_buffer(ctx, value, value_length));
 }
 
diff --git a/src/core/transport/metadata.h b/src/core/transport/metadata.h
index 99b15322c3..15ef9bb555 100644
--- a/src/core/transport/metadata.h
+++ b/src/core/transport/metadata.h
@@ -95,7 +95,7 @@ size_t grpc_mdctx_get_mdtab_free_test_only(grpc_mdctx *mdctx);
 
 /* Constructors for grpc_mdstr instances; take a variety of data types that
    clients may have handy */
-grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str);
+grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str, int perform_key_canonicalization);
 /* Unrefs the slice. */
 grpc_mdstr *grpc_mdstr_from_slice(grpc_mdctx *ctx, gpr_slice slice);
 grpc_mdstr *grpc_mdstr_from_buffer(grpc_mdctx *ctx, const gpr_uint8 *str,
@@ -117,7 +117,8 @@ grpc_mdelem *grpc_mdelem_from_slices(grpc_mdctx *ctx, gpr_slice key,
 grpc_mdelem *grpc_mdelem_from_string_and_buffer(grpc_mdctx *ctx,
                                                 const char *key,
                                                 const gpr_uint8 *value,
-                                                size_t value_length);
+                                                size_t value_length,
+                                                int canonicalize_key);
 
 /* Mutator and accessor for grpc_mdelem user data. The destructor function
    is used as a type tag and is checked during user_data fetch. */
diff --git a/src/core/transport/stream_op.c b/src/core/transport/stream_op.c
index fdb50c6b71..a5dfec9d50 100644
--- a/src/core/transport/stream_op.c
+++ b/src/core/transport/stream_op.c
@@ -205,7 +205,7 @@ void grpc_metadata_batch_assert_ok(grpc_metadata_batch *batch) {
 void grpc_metadata_batch_init(grpc_metadata_batch *batch) {
   batch->list.head = batch->list.tail = batch->garbage.head = batch->garbage.tail =
       NULL;
-  batch->deadline = gpr_inf_future;
+  batch->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 void grpc_metadata_batch_destroy(grpc_metadata_batch *batch) {
@@ -286,6 +286,12 @@ void grpc_metadata_batch_merge(grpc_metadata_batch *target,
   }
 }
 
+void grpc_metadata_batch_move(grpc_metadata_batch *dst,
+                               grpc_metadata_batch *src) {
+  *dst = *src;
+  memset(src, 0, sizeof(grpc_metadata_batch));
+}
+
 void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
                                 grpc_mdelem *(*filter)(void *user_data,
                                                        grpc_mdelem *elem),
diff --git a/src/core/transport/stream_op.h b/src/core/transport/stream_op.h
index 7d3024da10..227320cf2a 100644
--- a/src/core/transport/stream_op.h
+++ b/src/core/transport/stream_op.h
@@ -102,6 +102,11 @@ void grpc_metadata_batch_destroy(grpc_metadata_batch *batch);
 void grpc_metadata_batch_merge(grpc_metadata_batch *target,
                                grpc_metadata_batch *add);
 
+/** Moves the metadata information from \a src to \a dst. Upon return, \a src is
+ * zeroed. */
+void grpc_metadata_batch_move(grpc_metadata_batch *dst,
+                              grpc_metadata_batch *src);
+
 /** Add \a storage to the beginning of \a batch. storage->md is
     assumed to be valid.
     \a storage is owned by the caller and must survive for the
diff --git a/src/core/transport/transport.c b/src/core/transport/transport.c
index 2689e3028a..c0d92cf93f 100644
--- a/src/core/transport/transport.c
+++ b/src/core/transport/transport.c
@@ -32,6 +32,8 @@
  */
 
 #include "src/core/transport/transport.h"
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
 #include "src/core/transport/transport_impl.h"
 
 size_t grpc_transport_stream_size(grpc_transport *transport) {
@@ -65,6 +67,10 @@ void grpc_transport_destroy_stream(grpc_transport *transport,
   transport->vtable->destroy_stream(transport, stream);
 }
 
+char *grpc_transport_get_peer(grpc_transport *transport) {
+  return transport->vtable->get_peer(transport);
+}
+
 void grpc_transport_stream_op_finish_with_failure(
     grpc_transport_stream_op *op) {
   if (op->send_ops) {
@@ -79,12 +85,54 @@ void grpc_transport_stream_op_finish_with_failure(
 }
 
 void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
-                                               grpc_status_code status,
-                                               grpc_mdstr *message) {
+                                               grpc_status_code status) {
+  GPR_ASSERT(status != GRPC_STATUS_OK);
   if (op->cancel_with_status == GRPC_STATUS_OK) {
     op->cancel_with_status = status;
   }
-  if (message) {
-    GRPC_MDSTR_UNREF(message);
+  if (op->close_with_status != GRPC_STATUS_OK) {
+    op->close_with_status = GRPC_STATUS_OK;
+    if (op->optional_close_message != NULL) {
+      gpr_slice_unref(*op->optional_close_message);
+      op->optional_close_message = NULL;
+    }
+  }
+}
+
+typedef struct {
+  gpr_slice message;
+  grpc_iomgr_closure *then_call;
+  grpc_iomgr_closure closure;
+} close_message_data;
+
+static void free_message(void *p, int iomgr_success) {
+  close_message_data *cmd = p;
+  gpr_slice_unref(cmd->message);
+  if (cmd->then_call != NULL) {
+    cmd->then_call->cb(cmd->then_call->cb_arg, iomgr_success);
+  }
+  gpr_free(cmd);
+}
+
+void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+                                        grpc_status_code status,
+                                        gpr_slice *optional_message) {
+  close_message_data *cmd;
+  GPR_ASSERT(status != GRPC_STATUS_OK);
+  if (op->cancel_with_status != GRPC_STATUS_OK ||
+      op->close_with_status != GRPC_STATUS_OK) {
+    if (optional_message) {
+      gpr_slice_unref(*optional_message);
+    }
+    return;
+  }
+  if (optional_message) {
+    cmd = gpr_malloc(sizeof(*cmd));
+    cmd->message = *optional_message;
+    cmd->then_call = op->on_consumed;
+    grpc_iomgr_closure_init(&cmd->closure, free_message, cmd);
+    op->on_consumed = &cmd->closure;
+    op->optional_close_message = &cmd->message;
   }
+  op->close_with_status = status;
 }
diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index 64503604ee..92c1f38c5e 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -80,8 +80,14 @@ typedef struct grpc_transport_stream_op {
 
   grpc_pollset *bind_pollset;
 
+  /** If != GRPC_STATUS_OK, cancel this stream */
   grpc_status_code cancel_with_status;
 
+  /** If != GRPC_STATUS_OK, send grpc-status, grpc-message, and close this
+      stream for both reading and writing */
+  grpc_status_code close_with_status;
+  gpr_slice *optional_close_message;
+
   /* Indexes correspond to grpc_context_index enum values */
   grpc_call_context_element *context;
 } grpc_transport_stream_op;
@@ -109,6 +115,8 @@ typedef struct grpc_transport_op {
   void *set_accept_stream_user_data;
   /** add this transport to a pollset */
   grpc_pollset *bind_pollset;
+  /** add this transport to a pollset_set */
+  grpc_pollset_set *bind_pollset_set;
   /** send a ping, call this back if not NULL */
   grpc_iomgr_closure *send_ping;
 } grpc_transport_op;
@@ -146,8 +154,11 @@ void grpc_transport_destroy_stream(grpc_transport *transport,
 void grpc_transport_stream_op_finish_with_failure(grpc_transport_stream_op *op);
 
 void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
-                                               grpc_status_code status,
-                                               grpc_mdstr *message);
+                                               grpc_status_code status);
+
+void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+                                        grpc_status_code status,
+                                        gpr_slice *optional_message);
 
 char *grpc_transport_stream_op_string(grpc_transport_stream_op *op);
 
@@ -182,4 +193,7 @@ void grpc_transport_close(grpc_transport *transport);
 /* Destroy the transport */
 void grpc_transport_destroy(grpc_transport *transport);
 
+/* Get the transports peer */
+char *grpc_transport_get_peer(grpc_transport *transport);
+
 #endif /* GRPC_INTERNAL_CORE_TRANSPORT_TRANSPORT_H */
diff --git a/src/core/transport/transport_impl.h b/src/core/transport/transport_impl.h
index 515721dfb6..d3bbdf6c27 100644
--- a/src/core/transport/transport_impl.h
+++ b/src/core/transport/transport_impl.h
@@ -58,6 +58,9 @@ typedef struct grpc_transport_vtable {
 
   /* implementation of grpc_transport_destroy */
   void (*destroy)(grpc_transport *self);
+
+  /* implementation of grpc_transport_get_peer */
+  char *(*get_peer)(grpc_transport *self);
 } grpc_transport_vtable;
 
 /* an instance of a grpc transport */
diff --git a/src/core/transport/transport_op_string.c b/src/core/transport/transport_op_string.c
index 862eb40c4b..f62c340e97 100644
--- a/src/core/transport/transport_op_string.c
+++ b/src/core/transport/transport_op_string.c
@@ -61,7 +61,7 @@ static void put_metadata_list(gpr_strvec *b, grpc_metadata_batch md) {
     if (m != md.list.head) gpr_strvec_add(b, gpr_strdup(", "));
     put_metadata(b, m->md);
   }
-  if (gpr_time_cmp(md.deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(md.deadline, gpr_inf_future(md.deadline.clock_type)) != 0) {
     char *tmp;
     gpr_asprintf(&tmp, " deadline=%d.%09d", md.deadline.tv_sec,
                  md.deadline.tv_nsec);
@@ -116,10 +116,9 @@ char *grpc_transport_stream_op_string(grpc_transport_stream_op *op) {
   if (op->send_ops) {
     if (!first) gpr_strvec_add(&b, gpr_strdup(" "));
     first = 0;
-    gpr_strvec_add(&b, gpr_strdup("SEND"));
-    if (op->is_last_send) {
-      gpr_strvec_add(&b, gpr_strdup("_LAST"));
-    }
+    gpr_asprintf(&tmp, "SEND%s:%p", op->is_last_send ? "_LAST" : "",
+                 op->on_done_send);
+    gpr_strvec_add(&b, tmp);
     gpr_strvec_add(&b, gpr_strdup("["));
     gpr_strvec_add(&b, grpc_sopb_string(op->send_ops));
     gpr_strvec_add(&b, gpr_strdup("]"));
@@ -128,7 +127,8 @@ char *grpc_transport_stream_op_string(grpc_transport_stream_op *op) {
   if (op->recv_ops) {
     if (!first) gpr_strvec_add(&b, gpr_strdup(" "));
     first = 0;
-    gpr_asprintf(&tmp, "RECV:max_recv_bytes=%d", op->max_recv_bytes);
+    gpr_asprintf(&tmp, "RECV:%p:max_recv_bytes=%d", op->on_done_recv,
+                 op->max_recv_bytes);
     gpr_strvec_add(&b, tmp);
   }
 
diff --git a/src/core/tsi/ssl_transport_security.c b/src/core/tsi/ssl_transport_security.c
index 6156a39d09..609fc06ed5 100644
--- a/src/core/tsi/ssl_transport_security.c
+++ b/src/core/tsi/ssl_transport_security.c
@@ -1293,8 +1293,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
     const size_t* pem_private_keys_sizes, const unsigned char** pem_cert_chains,
     const size_t* pem_cert_chains_sizes, size_t key_cert_pair_count,
     const unsigned char* pem_client_root_certs,
-    size_t pem_client_root_certs_size, const char* cipher_list,
-    const unsigned char** alpn_protocols,
+    size_t pem_client_root_certs_size, int force_client_auth,
+    const char* cipher_list, const unsigned char** alpn_protocols,
     const unsigned char* alpn_protocols_lengths, uint16_t num_alpn_protocols,
     tsi_ssl_handshaker_factory** factory) {
   tsi_ssl_server_handshaker_factory* impl = NULL;
@@ -1349,6 +1349,7 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
       if (result != TSI_OK) break;
 
       if (pem_client_root_certs != NULL) {
+        int flags = SSL_VERIFY_PEER;
         STACK_OF(X509_NAME)* root_names = NULL;
         result = ssl_ctx_load_verification_certs(
             impl->ssl_contexts[i], pem_client_root_certs,
@@ -1358,7 +1359,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
           break;
         }
         SSL_CTX_set_client_CA_list(impl->ssl_contexts[i], root_names);
-        SSL_CTX_set_verify(impl->ssl_contexts[i], SSL_VERIFY_PEER, NULL);
+        if (force_client_auth) flags |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
+        SSL_CTX_set_verify(impl->ssl_contexts[i], flags, NULL);
         /* TODO(jboeuf): Add revocation verification. */
       }
 
diff --git a/src/core/tsi/ssl_transport_security.h b/src/core/tsi/ssl_transport_security.h
index b2aa2f393e..4bf6c81b75 100644
--- a/src/core/tsi/ssl_transport_security.h
+++ b/src/core/tsi/ssl_transport_security.h
@@ -107,10 +107,14 @@ tsi_result tsi_create_ssl_client_handshaker_factory(
    - key_cert_pair_count indicates the number of items in the private_key_files
      and cert_chain_files parameters.
    - pem_client_roots is the buffer containing the PEM encoding of the client
-     root certificates. This parameter may be NULL in which case the server
-     will not ask the client to authenticate itself with a certificate (server-
-     only authentication mode).
-   - pem_client_roots_size is the size of the associated buffer.
+     root certificates. This parameter may be NULL in which case the server will
+     not authenticate the client. If not NULL, the force_client_auth parameter
+     specifies if the server will accept only authenticated clients or both
+     authenticated and non-authenticated clients.
+   - pem_client_root_certs_size is the size of the associated buffer.
+   - force_client_auth, if set to non-zero will force the client to authenticate
+     with an SSL cert. Note that this option is ignored if pem_client_root_certs
+     is NULL or pem_client_roots_certs_size is 0
    - cipher_suites contains an optional list of the ciphers that the server
      supports. The format of this string is described in:
      https://www.openssl.org/docs/apps/ciphers.html.
@@ -131,8 +135,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
     const size_t* pem_private_keys_sizes, const unsigned char** pem_cert_chains,
     const size_t* pem_cert_chains_sizes, size_t key_cert_pair_count,
     const unsigned char* pem_client_root_certs,
-    size_t pem_client_root_certs_size, const char* cipher_suites,
-    const unsigned char** alpn_protocols,
+    size_t pem_client_root_certs_size, int force_client_auth,
+    const char* cipher_suites, const unsigned char** alpn_protocols,
     const unsigned char* alpn_protocols_lengths, uint16_t num_alpn_protocols,
     tsi_ssl_handshaker_factory** factory);