Disable P2P net option by default (#1793)

src/init.cc

@@ -504,7 +504,7 @@ static ncclResult_t commFree(ncclComm_t comm) {
   return ncclSuccess;
 }
 
-RCCL_PARAM(P2pNetDisable, "P2P_NET_DISABLE", 0);
+RCCL_PARAM(P2pNetDisable, "P2P_NET_DISABLE", 1);
 RCCL_PARAM(PivotAlltoallEnable, "PIVOT_ALLTOALL_ENABLE", 1);
 RCCL_PARAM(LL128ForceEnable, "LL128_FORCE_ENABLE", 0);
 NCCL_PARAM(AggChannelSize, "AGG_CHANNEL_SIZE", -2);