InfiniBand · IB
A low-latency lossless fabric with native RDMA, the historical default for non-blocking AI training back-ends.
Current numbers
2x400GbEConnectX-8: one 800 Gb/s port runs Ethernet as 2×400GbE (single 800GbE unsupported) and XDR IB at 800G; the dual-plane substrate
~16 → ≤6 SMsGPU SMs consumed by a reduction after composing NVLink-SHARP + IB-SHARP in NCCL 2.27
<100 ns switching; as low as 1 µs application (2012 examples)InfiniBand switch-hop and best-case application latency quoted in Mellanox’s 2012 trading solution brief