diff --git a/include/mscclpp/core.hpp b/include/mscclpp/core.hpp
index 37bdbd514..16e8858a3 100644
--- a/include/mscclpp/core.hpp
+++ b/include/mscclpp/core.hpp
@@ -8,6 +8,7 @@
 #include <bitset>
 #include <future>
 #include <memory>
+#include <mscclpp/env.hpp>
 #include <mscclpp/errors.hpp>
 #include <mscclpp/gpu_data_types.hpp>
 #include <mscclpp/version.hpp>
@@ -430,7 +431,7 @@ struct EndpointConfig {
        int maxWrPerSend = DefaultMaxWrPerSend, Mode mode = Mode::Default)
         : deviceIndex(deviceIndex),
           port(port),
-          gidIndex(gidIndex),
+          gidIndex(env()->ibGidIndex >= 0 ? env()->ibGidIndex : gidIndex),
           maxCqSize(maxCqSize),
           maxCqPollNum(maxCqPollNum),
           maxSendWr(maxSendWr),
diff --git a/include/mscclpp/env.hpp b/include/mscclpp/env.hpp
index 39f73e8d8..696255d23 100644
--- a/include/mscclpp/env.hpp
+++ b/include/mscclpp/env.hpp
@@ -110,6 +110,11 @@ class Env {
   /// Default is false.
   const bool forceDisableNvls;
 
+  /// Env name: `MSCCLPP_IB_GID_INDEX`. The GID index to use for IB transport.
+  /// When set to a non-negative value, overrides the `gidIndex` parameter passed to `EndpointConfig::Ib`.
+  /// Default is -1 (unset, uses the constructor argument which defaults to `EndpointConfig::Ib::DefaultGidIndex`).
+  const int ibGidIndex;
+
  private:
   Env();
 
diff --git a/python/csrc/env_py.cpp b/python/csrc/env_py.cpp
index ce89fd3da..c1d465ae9 100644
--- a/python/csrc/env_py.cpp
+++ b/python/csrc/env_py.cpp
@@ -23,7 +23,12 @@ void register_env(nb::module_& m) {
       .def_ro("ibv_mode", &Env::ibvMode)
       .def_ro("cache_dir", &Env::cacheDir)
       .def_ro("npkit_dump_dir", &Env::npkitDumpDir)
-      .def_ro("cuda_ipc_use_default_stream", &Env::cudaIpcUseDefaultStream);
+      .def_ro("cuda_ipc_use_default_stream", &Env::cudaIpcUseDefaultStream)
+      .def_ro("nccl_shared_lib_path", &Env::ncclSharedLibPath)
+      .def_ro("force_nccl_fallback_operation", &Env::forceNcclFallbackOperation)
+      .def_ro("nccl_symmetric_memory", &Env::ncclSymmetricMemory)
+      .def_ro("force_disable_nvls", &Env::forceDisableNvls)
+      .def_ro("ib_gid_index", &Env::ibGidIndex);
 
   m.def("env", &env);
 }
diff --git a/src/core/env.cpp b/src/core/env.cpp
index 484b40af1..4e25bfeaf 100644
--- a/src/core/env.cpp
+++ b/src/core/env.cpp
@@ -65,7 +65,8 @@ Env::Env()
       ncclSharedLibPath(readEnv<std::string>("MSCCLPP_NCCL_LIB_PATH", "")),
       forceNcclFallbackOperation(readEnv<std::string>("MSCCLPP_FORCE_NCCL_FALLBACK_OPERATION", "")),
       ncclSymmetricMemory(readEnv<bool>("MSCCLPP_NCCL_SYMMETRIC_MEMORY", false)),
-      forceDisableNvls(readEnv<bool>("MSCCLPP_FORCE_DISABLE_NVLS", false)) {}
+      forceDisableNvls(readEnv<bool>("MSCCLPP_FORCE_DISABLE_NVLS", false)),
+      ibGidIndex(readEnv<int>("MSCCLPP_IB_GID_INDEX", -1)) {}
 
 std::shared_ptr<Env> env() {
   static std::shared_ptr<Env> globalEnv = std::shared_ptr<Env>(new Env());
@@ -93,6 +94,7 @@ std::shared_ptr<Env> env() {
     logEnv("MSCCLPP_FORCE_NCCL_FALLBACK_OPERATION", globalEnv->forceNcclFallbackOperation);
     logEnv("MSCCLPP_NCCL_SYMMETRIC_MEMORY", globalEnv->ncclSymmetricMemory);
     logEnv("MSCCLPP_FORCE_DISABLE_NVLS", globalEnv->forceDisableNvls);
+    logEnv("MSCCLPP_IB_GID_INDEX", globalEnv->ibGidIndex);
   }
   return globalEnv;
 }
diff --git a/src/core/executor/executor.cc b/src/core/executor/executor.cc
index bf2caf97f..9229f9ac8 100644
--- a/src/core/executor/executor.cc
+++ b/src/core/executor/executor.cc
@@ -109,7 +109,7 @@ namespace mscclpp {
 
 struct ExecutionContext {
   std::shared_ptr<ProxyService> proxyService;
-  std::unordered_map<int, Connection> connections;
+  std::vector<Connection> connections;
   std::vector<std::shared_ptr<NvlsConnection>> nvlsConnections;
   MemoryId localMemoryIdBegin = MemoryId(0);
 
@@ -121,8 +121,6 @@ struct ExecutionContext {
   // local registered memories to keep resources alive
   std::vector<mscclpp::RegisteredMemory> localRegisteredMemories;
 
-  std::vector<std::shared_ptr<mscclpp::MemoryDevice2DeviceSemaphore>> memorySemaphores;
-  std::vector<mscclpp::SemaphoreId> proxySemaphores;
   std::vector<mscclpp::BaseMemoryChannel> memoryChannels;
   std::vector<mscclpp::BasePortChannel> portChannels;
   std::vector<mscclpp::SwitchChannel> nvlsChannels;
@@ -266,15 +264,28 @@ struct Executor::Impl {
       }
     };
 
-    std::vector<int> connectedPeers = plan.impl_->getConnectedPeers();
-    std::vector<std::shared_future<mscclpp::Connection>> connectionFutures;
-    for (int peer : connectedPeers) {
-      Transport transport =
-          !useIB(rank, peer, this->nranksPerNode) ? Transport::CudaIpc : IBs[rank % this->nranksPerNode];
-      connectionFutures.push_back(this->comm->connect(transport, peer));
+    std::unordered_map<int, int> peerTags;
+    Transport ibTransport = IBs[rank % this->nranksPerNode];
+    std::vector<std::shared_future<Connection>> connFutures;
+    for (ChannelType channelType : {ChannelType::MEMORY, ChannelType::PORT}) {
+      std::vector<ChannelInfo> channelInfos = plan.impl_->getChannelInfos(channelType);
+      for (const auto& info : channelInfos) {
+        for (int peer : info.connectedPeers) {
+          Transport transport = useIB(rank, peer, this->nranksPerNode) ? ibTransport : Transport::CudaIpc;
+          connFutures.push_back(this->comm->connect(transport, peer, peerTags[peer]++));
+        }
+      }
+      channelInfos = plan.impl_->getUnpairedChannelInfos(nranks, channelType);
+      for (const auto& info : channelInfos) {
+        for (int peer : info.connectedPeers) {
+          Transport transport = useIB(rank, peer, this->nranksPerNode) ? ibTransport : Transport::CudaIpc;
+          connFutures.push_back(this->comm->connect(transport, peer, peerTags[peer]++));
+        }
+      }
     }
-    for (size_t i = 0; i < connectionFutures.size(); i++) {
-      context.connections[connectedPeers[i]] = connectionFutures[i].get();
+
+    for (auto& future : connFutures) {
+      context.connections.push_back(future.get());
     }
 
     std::vector<NvlsInfo> nvlsInfos = plan.impl_->nvlsInfos.at(rank);
@@ -328,10 +339,11 @@ struct Executor::Impl {
     std::vector<std::shared_future<Semaphore>> futureProxySemaphores;
     std::vector<std::shared_ptr<MemoryDevice2DeviceSemaphore>> memorySemaphores;
     std::vector<mscclpp::SemaphoreId> proxySemaphores;
+    int connIdx = 0;
     auto processChannelInfos = [&](std::vector<ChannelInfo>& channelInfos) {
       for (ChannelInfo& info : channelInfos) {
-        for (int peer : info.connectedPeers) {
-          auto connection = context.connections.at(peer);
+        for (size_t i = 0; i < info.connectedPeers.size(); i++) {
+          auto& connection = context.connections[connIdx++];
           if (info.channelType == ChannelType::MEMORY) {
             futureMemorySemaphores.push_back(this->comm->buildSemaphore(
                 connection, this->comm->remoteRankOf(connection), this->comm->tagOf(connection)));
@@ -360,18 +372,15 @@ struct Executor::Impl {
       proxySemaphores.push_back(context.proxyService->addSemaphore(sem.get()));
     }
 
-    context.memorySemaphores = std::move(memorySemaphores);
-    context.proxySemaphores = std::move(proxySemaphores);
-
     for (ChannelType channelType : channelTypes) {
       std::vector<ChannelInfo> channelInfos = plan.impl_->getChannelInfos(channelType);
       int index = 0;
       for (ChannelInfo& info : channelInfos) {
         for (size_t i = 0; i < info.connectedPeers.size(); i++) {
           if (channelType == ChannelType::MEMORY) {
-            context.memoryChannels.emplace_back(context.memorySemaphores[index++]);
+            context.memoryChannels.emplace_back(memorySemaphores[index++]);
           } else if (channelType == ChannelType::PORT) {
-            context.portChannels.emplace_back(context.proxyService->basePortChannel(context.proxySemaphores[index++]));
+            context.portChannels.emplace_back(context.proxyService->basePortChannel(proxySemaphores[index++]));
           }
         }
       }