> ## Documentation Index
> Fetch the complete documentation index at: https://docs.coreweave.com/llms.txt
> Use this file to discover all available pages before exploring further.

# How do I configure InfiniBand and RDMA for multi-node training?

Request InfiniBand resources in your Pod's container spec with `rdma/ib: 1` (the same resource is used for both InfiniBand and RoCE Nodes). Set the NCCL and UCX environment variables that CoreWeave documents: `NCCL_SOCKET_IFNAME=eth0`, `NCCL_IB_HCA=ibp`, `UCX_TLS=tcp`, and `UCX_NET_DEVICES=eth0`. These ensure NCCL uses the InfiniBand HCA instead of falling back to TCP. Schedule the Pods onto Nodes with InfiniBand support, and verify from inside the Pod with `ibstat` that interfaces show `State: Active` and `Physical state: LinkUp`.

For full details and a complete Pod YAML, see [Use GPUDirect RDMA with InfiniBand](/products/networking/hpc-interconnect/use-gpudirect-rdma). If performance is poor after configuration, see [Why is my multi-node NCCL training slow?](/support/platform/articles/why-is-my-multi-node-nccl-training-slow).

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