InfiniBand · IB
A low-latency lossless fabric with native RDMA, the historical default for non-blocking AI training back-ends.
Current numbers
~100 ns switch hop; ~1 us cited application examplefabric latency must name its measurement boundary: NVIDIA cites about 100 ns for an InfiniBand switch hop and about 1 microsecond in application-latency examples; NIC-to-NIC and RoCEv2 results are topology, NIC, software and workload specific
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