MRC · Multipath Reliable Connection
An open RoCEv2 extension adding packet spray, trimming, and selective acknowledgment; already proven at frontier training scale, but training-first in scope rather than a general-purpose transport.
Current numbers
May 2026MRC public release: an OpenAI-led open OCP spec, a RoCEv2 extension already in production at 50k–75k GPUs
131,072GPUs in a two-tier 512×100G fabric, 800G NICs split into eight 100G planes (MRC design; deployed at 4×200G and 8×100G)