diff --git a/tools/topo_expl/model.cpp b/tools/topo_expl/model.cpp
index 910da923e1..9c4449f280 100644
--- a/tools/topo_expl/model.cpp
+++ b/tools/topo_expl/model.cpp
@@ -78,7 +78,7 @@ int busIdToCudaDev(int64_t busId) {
 static int useMemcpy = 0;
 
 /* Determine if two peers can communicate with P2P */
-ncclResult_t p2pCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
+ncclResult_t p2pCanConnect(int* ret,  struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
   if (!info1->hasFineGrain || !info2->hasFineGrain)  {
     *ret = 0;
     return ncclSuccess;
@@ -92,7 +92,7 @@ ncclResult_t p2pCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTop
 
   // Check topology / p2p level.
   int intermediateRank;
-  NCCLCHECK(ncclTopoCheckP2p(topo, info1->busId, info2->busId, ret, NULL, &intermediateRank));
+  NCCLCHECK(ncclTopoCheckP2p(comm->topo, info1->rank, info2->rank, ret, NULL, &intermediateRank));
   if (*ret == 0) return ncclSuccess;
   if (intermediateRank != -1) {
     if (useMemcpy) *ret = 0;
@@ -101,7 +101,7 @@ ncclResult_t p2pCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTop
 
   // Check if NET would work better
   int useNet = 0;
-  NCCLCHECK(ncclTopoCheckNet(topo, info1->busId, info2->busId, &useNet));
+  NCCLCHECK(ncclTopoCheckNet(comm->topo, info1->rank, info2->rank, &useNet));
   if (useNet) {
     *ret = 0;
     return ncclSuccess;
@@ -146,12 +146,12 @@ struct ncclTransport p2pTransport = {
 NCCL_PARAM(ShmDisable, "SHM_DISABLE", 0);
 
 /* Determine if two peers can communicate with SHM */
-ncclResult_t shmCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
+ncclResult_t shmCanConnect(int* ret,  struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
   *ret = 0;
   if (ncclParamShmDisable() == 1) return ncclSuccess;
 
   int useNet = 0;
-  NCCLCHECK(ncclTopoCheckNet(topo, info1->busId, info2->busId, &useNet));
+  NCCLCHECK(ncclTopoCheckNet(comm->topo, info1->rank, info2->rank, &useNet));
   if (useNet) return ncclSuccess;
 
   // Same host?
@@ -197,7 +197,7 @@ struct setupReq {
 };
 
 /* Determine if two peers can communicate with NET */
-ncclResult_t netCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
+ncclResult_t netCanConnect(int* ret,  struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
   *ret = 1;
   return ncclSuccess;
 }
@@ -257,7 +257,7 @@ struct ncclTransport netTransport = {
 };
 
 /* Determine if two peers can communicate with NET */
-ncclResult_t collNetCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
+ncclResult_t collNetCanConnect(int* ret,  struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
   *ret = 1;
   return ncclSuccess;
 }
diff --git a/tools/topo_expl/utils.cpp b/tools/topo_expl/utils.cpp
index 2e793b8346..340f1fff50 100644
--- a/tools/topo_expl/utils.cpp
+++ b/tools/topo_expl/utils.cpp
@@ -353,7 +353,7 @@ static ncclResult_t selectTransport(struct ncclComm* comm, struct ncclTopoGraph*
     struct ncclTransport *transport = ncclTransports[t];
     struct ncclTransportComm* transportComm = type == 1 ? &transport->send : &transport->recv;
     int ret = 0;
-    NCCLCHECK(transport->canConnect(&ret, comm->topo, graph, myInfo, peerInfo));
+    NCCLCHECK(transport->canConnect(&ret, comm, graph, myInfo, peerInfo));
     if (ret) {
       connector->transportComm = transportComm;
       NCCLCHECK(transportComm->setup(comm, graph, myInfo, peerInfo, connect, connector, channelId, connIndex));
@@ -721,7 +721,7 @@ ncclResult_t initTransportsRank_1(struct ncclComm* comm, struct allGatherInfo *a
   //struct ncclTopoGraph treeGraph;
   //struct ncclTopoGraph collNetGraph;
   //struct ncclTopoGraph nvlsGraph;
-  struct ncclTopoGraph* graphs[] = { &treeGraph, &ringGraph, &collNetGraph, &collNetGraph, &nvlsGraph, &nvlsGraph };
+  struct ncclTopoGraph* graphs[] = { &treeGraph, &ringGraph, &collNetGraph, &collNetGraph, &nvlsGraph, &nvlsGraph, &nvlsGraph};
 
   int nChannelsOrig;
   struct ncclTopoRanks** allTopoRanks = NULL;
@@ -963,6 +963,7 @@ ncclResult_t initTransportsRank_1(struct ncclComm* comm, struct allGatherInfo *a
   }
 
   comm->nChannels = std::min(treeGraph.nChannels, ringGraph.nChannels);
+  TRACE(NCCL_INIT,"treeGraph.nChannels: %d , ringGraph.nChannels: %d", treeGraph.nChannels, ringGraph.nChannels);
   NCCLCHECKGOTO(ncclTopoPreset(comm, graphs, &allGather3Data[rank].topoRanks), ret, fail);
 fail:
   return ret;
@@ -975,7 +976,7 @@ ncclResult_t initTransportsRank_3(struct ncclComm* comm, struct allGatherInfo *a
   int nranks = comm->nRanks;
   cpu_set_t affinitySave;
 
-  struct ncclTopoGraph* graphs[] = { &treeGraph, &ringGraph, &collNetGraph, &collNetGraph, &nvlsGraph, &nvlsGraph };
+  struct ncclTopoGraph* graphs[] = { &treeGraph, &ringGraph, &collNetGraph, &collNetGraph, &nvlsGraph, &nvlsGraph, &nvlsGraph};
 
   int nChannelsOrig;
   struct ncclTopoRanks** allTopoRanks = NULL;
@@ -1090,6 +1091,7 @@ ncclResult_t initTransportsRank_3(struct ncclComm* comm, struct allGatherInfo *a
   }
 
   NCCLCHECKGOTO(ncclCalloc(&rings, nranks*MAXCHANNELS), ret, fail);
+  TRACE(NCCL_INIT, "rank %d nranks %d nchannels %d", rank, nranks, comm->nChannels);
 
   NCCLCHECKGOTO(ncclTopoPostset(comm, nodesFirstRank, nodesTreePatterns, allTopoRanks, rings, graphs, NULL, nc), ret, fail);
   if (comm->topo->treeDefined) NCCLCHECK(ncclTreeBasePostset(comm, &treeGraph));