InfiniBand · IB
A low-latency lossless fabric with native RDMA, the historical default for non-blocking AI training back-ends.
Current numbers
2x400GbEConnectX-8: the single 800 Gb/s physical port runs Ethernet as 2×400GbE (single 800GbE link unsupported; XDR IB carries 800G on the same port) — the dual-plane substrate
80–90%share of the InfiniBand throughput gap careful DCQCN tuning closes on a 100k H100-class RoCEv2 fabric — analyst estimate, not a portable acceptance target
~16 → ≤6 SMsGPU SMs consumed by a reduction after composing NVLink-SHARP + IB-SHARP in NCCL 2.27