diff --git a/BUILD b/BUILD
index c02fb9d..d08d4b8 100644
--- a/BUILD
+++ b/BUILD
@@ -178,6 +178,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.h",
     "src/core/client_config/subchannel.h",
     "src/core/client_config/subchannel_factory.h",
+    "src/core/client_config/subchannel_index.h",
     "src/core/client_config/uri_parser.h",
     "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
@@ -316,6 +317,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.c",
     "src/core/client_config/subchannel.c",
     "src/core/client_config/subchannel_factory.c",
+    "src/core/client_config/subchannel_index.c",
     "src/core/client_config/uri_parser.c",
     "src/core/compression/algorithm.c",
     "src/core/compression/message_compress.c",
@@ -470,6 +472,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.h",
     "src/core/client_config/subchannel.h",
     "src/core/client_config/subchannel_factory.h",
+    "src/core/client_config/subchannel_index.h",
     "src/core/client_config/uri_parser.h",
     "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
@@ -588,6 +591,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.c",
     "src/core/client_config/subchannel.c",
     "src/core/client_config/subchannel_factory.c",
+    "src/core/client_config/subchannel_index.c",
     "src/core/client_config/uri_parser.c",
     "src/core/compression/algorithm.c",
     "src/core/compression/message_compress.c",
@@ -1123,6 +1127,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.c",
     "src/core/client_config/subchannel.c",
     "src/core/client_config/subchannel_factory.c",
+    "src/core/client_config/subchannel_index.c",
     "src/core/client_config/uri_parser.c",
     "src/core/compression/algorithm.c",
     "src/core/compression/message_compress.c",
@@ -1275,6 +1280,7 @@
     "src/core/client_config/resolvers/sockaddr_resolver.h",
     "src/core/client_config/subchannel.h",
     "src/core/client_config/subchannel_factory.h",
+    "src/core/client_config/subchannel_index.h",
     "src/core/client_config/uri_parser.h",
     "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
diff --git a/Makefile b/Makefile
index 6d15a57..9cfa97f 100644
--- a/Makefile
+++ b/Makefile
@@ -2356,6 +2356,7 @@
     src/core/client_config/resolvers/sockaddr_resolver.c \
     src/core/client_config/subchannel.c \
     src/core/client_config/subchannel_factory.c \
+    src/core/client_config/subchannel_index.c \
     src/core/client_config/uri_parser.c \
     src/core/compression/algorithm.c \
     src/core/compression/message_compress.c \
@@ -2659,6 +2660,7 @@
     src/core/client_config/resolvers/sockaddr_resolver.c \
     src/core/client_config/subchannel.c \
     src/core/client_config/subchannel_factory.c \
+    src/core/client_config/subchannel_index.c \
     src/core/client_config/uri_parser.c \
     src/core/compression/algorithm.c \
     src/core/compression/message_compress.c \
diff --git a/binding.gyp b/binding.gyp
index a5e9933..8f331c7 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -210,6 +210,7 @@
         'src/core/client_config/resolvers/sockaddr_resolver.c',
         'src/core/client_config/subchannel.c',
         'src/core/client_config/subchannel_factory.c',
+        'src/core/client_config/subchannel_index.c',
         'src/core/client_config/uri_parser.c',
         'src/core/compression/algorithm.c',
         'src/core/compression/message_compress.c',
diff --git a/build.yaml b/build.yaml
index 70a8dee..9a675fd 100644
--- a/build.yaml
+++ b/build.yaml
@@ -132,6 +132,7 @@
   - src/core/client_config/resolvers/sockaddr_resolver.h
   - src/core/client_config/subchannel.h
   - src/core/client_config/subchannel_factory.h
+  - src/core/client_config/subchannel_index.h
   - src/core/client_config/uri_parser.h
   - src/core/compression/algorithm_metadata.h
   - src/core/compression/message_compress.h
@@ -247,6 +248,7 @@
   - src/core/client_config/resolvers/sockaddr_resolver.c
   - src/core/client_config/subchannel.c
   - src/core/client_config/subchannel_factory.c
+  - src/core/client_config/subchannel_index.c
   - src/core/client_config/uri_parser.c
   - src/core/compression/algorithm.c
   - src/core/compression/message_compress.c
diff --git a/gRPC.podspec b/gRPC.podspec
index 97e13c0..0c34ed0 100644
--- a/gRPC.podspec
+++ b/gRPC.podspec
@@ -182,6 +182,7 @@
                       'src/core/client_config/resolvers/sockaddr_resolver.h',
                       'src/core/client_config/subchannel.h',
                       'src/core/client_config/subchannel_factory.h',
+                      'src/core/client_config/subchannel_index.h',
                       'src/core/client_config/uri_parser.h',
                       'src/core/compression/algorithm_metadata.h',
                       'src/core/compression/message_compress.h',
@@ -327,6 +328,7 @@
                       'src/core/client_config/resolvers/sockaddr_resolver.c',
                       'src/core/client_config/subchannel.c',
                       'src/core/client_config/subchannel_factory.c',
+                      'src/core/client_config/subchannel_index.c',
                       'src/core/client_config/uri_parser.c',
                       'src/core/compression/algorithm.c',
                       'src/core/compression/message_compress.c',
@@ -481,6 +483,7 @@
                               'src/core/client_config/resolvers/sockaddr_resolver.h',
                               'src/core/client_config/subchannel.h',
                               'src/core/client_config/subchannel_factory.h',
+                              'src/core/client_config/subchannel_index.h',
                               'src/core/client_config/uri_parser.h',
                               'src/core/compression/algorithm_metadata.h',
                               'src/core/compression/message_compress.h',
diff --git a/include/grpc/grpc.h b/include/grpc/grpc.h
index 952e86e..22a6606 100644
--- a/include/grpc/grpc.h
+++ b/include/grpc/grpc.h
@@ -77,6 +77,12 @@
   GRPC_ARG_POINTER
 } grpc_arg_type;
 
+typedef struct grpc_arg_pointer_vtable {
+  void *(*copy)(void *p);
+  void (*destroy)(void *p);
+  int (*cmp)(void *p, void *q);
+} grpc_arg_pointer_vtable;
+
 /** A single argument... each argument has a key and a value
 
     A note on naming keys:
@@ -97,8 +103,7 @@
     int integer;
     struct {
       void *p;
-      void *(*copy)(void *p);
-      void (*destroy)(void *p);
+      const grpc_arg_pointer_vtable *vtable;
     } pointer;
   } value;
 } grpc_arg;
diff --git a/include/grpc/support/useful.h b/include/grpc/support/useful.h
index 9f08d78..003e096 100644
--- a/include/grpc/support/useful.h
+++ b/include/grpc/support/useful.h
@@ -72,4 +72,6 @@
     0x0f0f0f0f) %                                \
    255)
 
+#define GPR_ICMP(a, b) ((a) < (b) ? -1 : ((a) > (b) ? 1 : 0))
+
 #endif /* GRPC_SUPPORT_USEFUL_H */
diff --git a/src/core/channel/channel_args.c b/src/core/channel/channel_args.c
index 487db11..cd35d2f 100644
--- a/src/core/channel/channel_args.c
+++ b/src/core/channel/channel_args.c
@@ -54,9 +54,7 @@
       break;
     case GRPC_ARG_POINTER:
       dst.value.pointer = src->value.pointer;
-      dst.value.pointer.p = src->value.pointer.copy
-                                ? src->value.pointer.copy(src->value.pointer.p)
-                                : src->value.pointer.p;
+      dst.value.pointer.p = src->value.pointer.vtable->copy(src->value.pointer.p);
       break;
   }
   return dst;
@@ -93,6 +91,60 @@
   return grpc_channel_args_copy_and_add(a, b->args, b->num_args);
 }
 
+static int cmp_arg(const grpc_arg *a, const grpc_arg *b) {
+  int c = a->type - b->type;
+  if (c != 0) return c;
+  c = strcmp(a->key, b->key);
+  if (c != 0) return c;
+  switch (a->type) {
+    case GRPC_ARG_STRING:
+      c = strcmp(a->value.string, b->value.string);
+      break;
+    case GRPC_ARG_INTEGER:
+      c = GPR_ICMP(a->value.integer, b->value.integer);
+      break;
+    case GRPC_ARG_POINTER:
+      c = GPR_ICMP(a->value.pointer.p, 
+                   b->value.pointer.p);
+      if (c != 0) {
+        c = GPR_ICMP(a->value.pointer.vtable, 
+                     b->value.pointer.vtable);
+        if (c == 0) {
+          c = a->value.pointer.vtable->cmp(a->value.pointer.p,
+                                           b->value.pointer.p);
+        }
+      }
+      break;
+  }
+  return c;
+}
+
+static int cmp_key_stable(const void *ap, const void *bp) {
+  const grpc_arg *const *a = ap;
+  const grpc_arg *const *b = bp;
+  int c = strcmp((*a)->key, (*b)->key);
+  if (c == 0) c = GPR_ICMP(*a, *b);
+  return c;
+}
+
+grpc_channel_args *grpc_channel_args_normalize(const grpc_channel_args *a) {
+  grpc_arg **args = gpr_malloc(sizeof(grpc_arg*) * a->num_args);
+  for (size_t i = 0; i < a->num_args; i++) {
+    args[i] = &a->args[i];
+  }
+  qsort(args, a->num_args, sizeof(grpc_arg*), cmp_key_stable);
+
+  grpc_channel_args *b = gpr_malloc(sizeof(grpc_channel_args));
+  b->num_args = a->num_args;
+  b->args = gpr_malloc(sizeof(grpc_arg) * b->num_args);
+  for (size_t i = 0; i < a->num_args; i++) {
+    b->args[i] = copy_arg(args[i]);
+  }
+
+  gpr_free(args);
+  return b;
+}
+
 void grpc_channel_args_destroy(grpc_channel_args *a) {
   size_t i;
   for (i = 0; i < a->num_args; i++) {
@@ -103,9 +155,7 @@
       case GRPC_ARG_INTEGER:
         break;
       case GRPC_ARG_POINTER:
-        if (a->args[i].value.pointer.destroy) {
-          a->args[i].value.pointer.destroy(a->args[i].value.pointer.p);
-        }
+        a->args[i].value.pointer.vtable->destroy(a->args[i].value.pointer.p);
         break;
     }
     gpr_free(a->args[i].key);
@@ -207,3 +257,14 @@
     return (1u << GRPC_COMPRESS_ALGORITHMS_COUNT) - 1; /* All algs. enabled */
   }
 }
+
+int grpc_channel_args_compare(const grpc_channel_args *a, 
+                              const grpc_channel_args *b) {
+  int c = GPR_ICMP(a->num_args, b->num_args);
+  if (c != 0) return c;
+  for (size_t i = 0; i < a->num_args; i++) {
+    c = cmp_arg(&a->args[i], &b->args[i]);
+    if (c != 0) return c;
+  }
+  return 0;
+}
diff --git a/src/core/channel/channel_args.h b/src/core/channel/channel_args.h
index 480cc9a..ce84878 100644
--- a/src/core/channel/channel_args.h
+++ b/src/core/channel/channel_args.h
@@ -40,6 +40,9 @@
 /* Copy some arguments */
 grpc_channel_args *grpc_channel_args_copy(const grpc_channel_args *src);
 
+/* Copy some arguments, stably sorting keys */
+grpc_channel_args *grpc_channel_args_normalize(const grpc_channel_args *a);
+
 /** Copy some arguments and add the to_add parameter in the end.
    If to_add is NULL, it is equivalent to call grpc_channel_args_copy. */
 grpc_channel_args *grpc_channel_args_copy_and_add(const grpc_channel_args *src,
@@ -85,4 +88,6 @@
 int grpc_channel_args_compression_algorithm_get_states(
     const grpc_channel_args *a);
 
+int grpc_channel_args_compare(const grpc_channel_args *a, const grpc_channel_args *b);
+
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_ARGS_H */
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 2992da8..9f287c4 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -36,6 +36,7 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/avl.h>
 
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
diff --git a/src/core/client_config/subchannel_index.c b/src/core/client_config/subchannel_index.c
new file mode 100644
index 0000000..ffe6c1f
--- /dev/null
+++ b/src/core/client_config/subchannel_index.c
@@ -0,0 +1,155 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+/* a map of subchannel_key --> subchannel, used for detecting connections
+   to the same destination in order to share them */
+static gpr_avl g_subchannel_index;
+
+static gpr_mu g_mu;
+
+struct subchannel_key {
+  size_t addr_len;
+  struct sockaddr *addr;
+  grpc_channel_args *normalized_args;
+};
+
+GPR_TLS_DECL(subchannel_index_exec_ctx);
+
+static subchannel_key *subchannel_key_create(struct sockaddr *sockaddr, size_t addr_len, grpc_channel_args *args) {
+  subchannel_key *k = gpr_malloc(sizeof(*k));
+  k->addr_len = addr_len;
+  k->addr = gpr_malloc(addr_len);
+  memcpy(k->addr, addr, addr_len);
+  k->normalized_args = grpc_channel_args_normalize(args);
+  return k;
+}
+
+static subchannel_key *subchannel_key_copy(subchannel_key *k) {
+  subchannel_key *k = gpr_malloc(sizeof(*k));
+  k->addr_len = addr_len;
+  k->addr = gpr_malloc(addr_len);
+  memcpy(k->addr, addr, addr_len);
+  k->normalized_args = grpc_channel_args_copy(args);
+  return k;
+}
+
+static int subchannel_key_compare(subchannel_key *a, subchannel_key *b) {
+  int c = GPR_ICMP(a->addr_len, b->addr_len);
+  if (c != 0) return c;
+  c = memcmp(a->addr, b->addr, a->addr_len);
+  if (c != 0) return c;
+  return grpc_channel_args_compare(a->normalized_args, b->normalized_args);
+}
+
+static void subchannel_key_destroy(subchannel_key *k) {
+  gpr_free(k->addr);
+  grpc_channel_args_destroy(k->normalized_args);
+  gpr_free(k);
+}
+
+static void sck_avl_destroy(void *p) {
+  subchannel_key_destroy(p);
+}
+
+static void *sck_avl_copy(void *p) {
+  return subchannel_key_copy(p);
+}
+
+static void *sck_avl_compare(void *a, void *b) {
+  return subchannel_key_compare(a, b);
+}
+
+static void scv_avl_destroy(void *p) {
+  GRPC_SUBCHANNEL_UNREF(exec_ctx, p, "subchannel_index");
+}
+
+static void *scv_avl_copy(void *p) { 
+  GRPC_SUBCHANNEL_REF(p, "subchannel_index");
+  return p; 
+}
+
+static const gpr_avl_vtable subchannel_avl_vtable = {
+  .destroy_key = sck_avl_destroy,
+  .copy_key = sck_avl_copy,
+  .compare_keys = sck_avl_compare,
+  .destroy_value = scv_avl_destroy,
+  .copy_value = scv_avl_copy  
+};
+
+grpc_subchannel *grpc_subchannel_index_find(
+		grpc_exec_ctx *ctx,
+		grpc_connector *connector,
+		grpc_subchannel_args *args) {
+	gpr_mu_lock(&g_mu);
+	gpr_avl index = gpr_avl_ref(g_subchannel_index);
+	gpr_mu_unlock(&g_mu);
+
+	subchannel_key *key = subchannel_key_create(connector, args);
+	grpc_subchannel *c = grpc_subchannel_ref(gpr_avl_get(index, key));
+	subchannel_key_destroy(key);
+	gpr_avl_unref(index);
+
+	return c;
+}
+
+grpc_subchannel *grpc_subchannel_index_register(
+	  grpc_exec_ctx *ctx,
+		grpc_connector *connector, 
+		grpc_subchannel_args *args, 
+		grpc_subchannel *constructed) {
+	subchannel_key *key = subchannel_key_create(connector, args);
+	grpc_subchannel *c = NULL;
+
+	while (c == NULL) {
+		gpr_mu_lock(&g_mu);
+		gpr_avl index = gpr_avl_ref(g_subchannel_index);
+		gpr_mu_unlock(&g_mu);
+
+		c = gpr_avl_get(index, key);
+		if (c != NULL) {
+			GRPC_SUBCHANNEL_UNREF(constructed);
+		} else {
+			gpr_avl updated = gpr_avl_add(index, key, constructed);
+
+			gpr_mu_lock(&g_mu);
+			if (index.root == g_subchannel_index.root) {
+				GPR_SWAP(index, g_subchannel_index);
+				c = constructed;
+			}
+			gpr_mu_unlock(&g_mu);
+		}
+		gpr_avl_unref(index);
+	}
+
+	return c;
+}
diff --git a/src/core/client_config/subchannel_index.h b/src/core/client_config/subchannel_index.h
new file mode 100644
index 0000000..d501e12
--- /dev/null
+++ b/src/core/client_config/subchannel_index.h
@@ -0,0 +1,39 @@
+/*
+ *
+ * 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_INDEX_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_INDEX_H
+
+
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_INDEX_H */
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index 8b56c57..28f41b2 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -196,14 +196,23 @@
   return grpc_server_credentials_ref(p);
 }
 
+static int server_credentials_pointer_cmp(void *a, void *b) {
+  return GPR_ICMP(a, b);
+}
+
+static const grpc_arg_pointer_vtable cred_ptr_vtable = {
+  server_credentials_pointer_arg_copy,
+  server_credentials_pointer_arg_destroy,
+  server_credentials_pointer_cmp
+};
+
 grpc_arg grpc_server_credentials_to_arg(grpc_server_credentials *p) {
   grpc_arg arg;
   memset(&arg, 0, sizeof(grpc_arg));
   arg.type = GRPC_ARG_POINTER;
   arg.key = GRPC_SERVER_CREDENTIALS_ARG;
   arg.value.pointer.p = p;
-  arg.value.pointer.copy = server_credentials_pointer_arg_copy;
-  arg.value.pointer.destroy = server_credentials_pointer_arg_destroy;
+  arg.value.pointer.vtable = &cred_ptr_vtable;
   return arg;
 }
 
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index 61336a1..40f4861 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -194,12 +194,21 @@
   return GRPC_SECURITY_CONNECTOR_REF(p, "connector_pointer_arg");
 }
 
+static int connector_pointer_cmp(void *a, void *b) {
+  return GPR_ICMP(a, b);
+}
+
+static const grpc_arg_pointer_vtable connector_pointer_vtable = {
+  connector_pointer_arg_copy,
+  connector_pointer_arg_destroy,
+  connector_pointer_cmp
+};
+
 grpc_arg grpc_security_connector_to_arg(grpc_security_connector *sc) {
   grpc_arg result;
   result.type = GRPC_ARG_POINTER;
   result.key = GRPC_SECURITY_CONNECTOR_ARG;
-  result.value.pointer.destroy = connector_pointer_arg_destroy;
-  result.value.pointer.copy = connector_pointer_arg_copy;
+  result.value.pointer.vtable = &connector_pointer_vtable;
   result.value.pointer.p = sc;
   return result;
 }
diff --git a/src/core/security/security_context.c b/src/core/security/security_context.c
index 2068c97..6e948f6 100644
--- a/src/core/security/security_context.c
+++ b/src/core/security/security_context.c
@@ -309,14 +309,23 @@
   return GRPC_AUTH_CONTEXT_REF(p, "auth_context_pointer_arg");
 }
 
+static int auth_context_pointer_cmp(void *a, void *b) {
+  return GPR_ICMP(a, b);
+}
+
+static const grpc_arg_pointer_vtable auth_context_pointer_vtable = {
+  auth_context_pointer_arg_copy,
+  auth_context_pointer_arg_destroy,
+  auth_context_pointer_cmp
+};
+
 grpc_arg grpc_auth_context_to_arg(grpc_auth_context *p) {
   grpc_arg arg;
   memset(&arg, 0, sizeof(grpc_arg));
   arg.type = GRPC_ARG_POINTER;
   arg.key = GRPC_AUTH_CONTEXT_ARG;
   arg.value.pointer.p = p;
-  arg.value.pointer.copy = auth_context_pointer_arg_copy;
-  arg.value.pointer.destroy = auth_context_pointer_arg_destroy;
+  arg.value.pointer.vtable = &auth_context_pointer_vtable;
   return arg;
 }
 
diff --git a/src/core/surface/init.c b/src/core/surface/init.c
index 19cea4c..8f19362 100644
--- a/src/core/surface/init.c
+++ b/src/core/surface/init.c
@@ -46,6 +46,7 @@
 #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/client_config/subchannel.h"
 #include "src/core/debug/trace.h"
 #include "src/core/iomgr/executor.h"
 #include "src/core/iomgr/iomgr.h"
@@ -125,6 +126,7 @@
     }
     gpr_timers_global_init();
     grpc_cq_global_init();
+    grpc_subchannel_global_init();
     for (i = 0; i < g_number_of_plugins; i++) {
       if (g_all_of_the_plugins[i].init != NULL) {
         g_all_of_the_plugins[i].init();
@@ -143,6 +145,7 @@
     grpc_executor_shutdown();
     grpc_cq_global_shutdown();
     grpc_iomgr_shutdown();
+    grpc_subchannel_global_shutdown();
     census_shutdown();
     gpr_timers_global_destroy();
     grpc_tracer_shutdown();
diff --git a/src/cpp/common/channel_arguments.cc b/src/cpp/common/channel_arguments.cc
index 90cd513..3536e35 100644
--- a/src/cpp/common/channel_arguments.cc
+++ b/src/cpp/common/channel_arguments.cc
@@ -62,9 +62,7 @@
         break;
       case GRPC_ARG_POINTER:
         ap.value.pointer = a->value.pointer;
-        ap.value.pointer.p = a->value.pointer.copy
-                                 ? a->value.pointer.copy(ap.value.pointer.p)
-                                 : ap.value.pointer.p;
+        ap.value.pointer.p = a->value.pointer.vtable->copy(ap.value.pointer.p);
         break;
     }
     args_.push_back(ap);
@@ -92,13 +90,27 @@
 }
 
 void ChannelArguments::SetPointer(const grpc::string& key, void* value) {
+  struct VtableMembers {
+    static void* Copy(void* in) { return in; }
+    static void Destroy(void* in) {}
+    static int Compare(void* a, void *b) {
+      if (a < b) return -1;
+      if (a > b) return 1;
+      return 0;
+    }
+  };
+  static const grpc_arg_pointer_vtable vtable = {
+    &VtableMembers::Copy,
+    &VtableMembers::Destroy,
+    &VtableMembers::Compare
+  };
+
   grpc_arg arg;
   arg.type = GRPC_ARG_POINTER;
   strings_.push_back(key);
   arg.key = const_cast<char*>(strings_.back().c_str());
   arg.value.pointer.p = value;
-  arg.value.pointer.copy = nullptr;
-  arg.value.pointer.destroy = nullptr;
+  arg.value.pointer.vtable = &vtable;
   args_.push_back(arg);
 }
 
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 952898d..8493bbd 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -119,6 +119,7 @@
   'src/core/client_config/resolvers/sockaddr_resolver.c',
   'src/core/client_config/subchannel.c',
   'src/core/client_config/subchannel_factory.c',
+  'src/core/client_config/subchannel_index.c',
   'src/core/client_config/uri_parser.c',
   'src/core/compression/algorithm.c',
   'src/core/compression/message_compress.c',
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 2280fde..9d5d967 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -807,6 +807,7 @@
 src/core/client_config/resolvers/sockaddr_resolver.h \
 src/core/client_config/subchannel.h \
 src/core/client_config/subchannel_factory.h \
+src/core/client_config/subchannel_index.h \
 src/core/client_config/uri_parser.h \
 src/core/compression/algorithm_metadata.h \
 src/core/compression/message_compress.h \
@@ -945,6 +946,7 @@
 src/core/client_config/resolvers/sockaddr_resolver.c \
 src/core/client_config/subchannel.c \
 src/core/client_config/subchannel_factory.c \
+src/core/client_config/subchannel_index.c \
 src/core/client_config/uri_parser.c \
 src/core/compression/algorithm.c \
 src/core/compression/message_compress.c \
diff --git a/tools/run_tests/sources_and_headers.json b/tools/run_tests/sources_and_headers.json
index 3e42c59..b01845c 100644
--- a/tools/run_tests/sources_and_headers.json
+++ b/tools/run_tests/sources_and_headers.json
@@ -2902,6 +2902,7 @@
       "src/core/client_config/resolvers/sockaddr_resolver.h", 
       "src/core/client_config/subchannel.h", 
       "src/core/client_config/subchannel_factory.h", 
+      "src/core/client_config/subchannel_index.h", 
       "src/core/client_config/uri_parser.h", 
       "src/core/compression/algorithm_metadata.h", 
       "src/core/compression/message_compress.h", 
@@ -3074,6 +3075,8 @@
       "src/core/client_config/subchannel.h", 
       "src/core/client_config/subchannel_factory.c", 
       "src/core/client_config/subchannel_factory.h", 
+      "src/core/client_config/subchannel_index.c", 
+      "src/core/client_config/subchannel_index.h", 
       "src/core/client_config/uri_parser.c", 
       "src/core/client_config/uri_parser.h", 
       "src/core/compression/algorithm.c", 
@@ -3415,6 +3418,7 @@
       "src/core/client_config/resolvers/sockaddr_resolver.h", 
       "src/core/client_config/subchannel.h", 
       "src/core/client_config/subchannel_factory.h", 
+      "src/core/client_config/subchannel_index.h", 
       "src/core/client_config/uri_parser.h", 
       "src/core/compression/algorithm_metadata.h", 
       "src/core/compression/message_compress.h", 
@@ -3572,6 +3576,8 @@
       "src/core/client_config/subchannel.h", 
       "src/core/client_config/subchannel_factory.c", 
       "src/core/client_config/subchannel_factory.h", 
+      "src/core/client_config/subchannel_index.c", 
+      "src/core/client_config/subchannel_index.h", 
       "src/core/client_config/uri_parser.c", 
       "src/core/client_config/uri_parser.h", 
       "src/core/compression/algorithm.c", 
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj b/vsprojects/vcxproj/grpc/grpc.vcxproj
index 8d6800e..db2c3ca 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj
@@ -316,6 +316,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\resolvers\sockaddr_resolver.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\uri_parser.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\compression\algorithm_metadata.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\compression\message_compress.h" />
@@ -504,6 +505,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\uri_parser.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\compression\algorithm.c">
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
index f29f881..c74e009 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
@@ -145,6 +145,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\uri_parser.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
@@ -599,6 +602,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\uri_parser.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
index 78ffe14..4d96e6d 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
@@ -292,6 +292,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\resolvers\sockaddr_resolver.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\uri_parser.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\compression\algorithm_metadata.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\compression\message_compress.h" />
@@ -440,6 +441,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\uri_parser.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\compression\algorithm.c">
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
index e068c3f..c84eeca 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
@@ -85,6 +85,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\client_config\uri_parser.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
@@ -494,6 +497,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_factory.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\client_config\subchannel_index.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\client_config\uri_parser.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>