Why it matters

RoCE competes with IB. Understanding shapes network choice.

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The architecture

Standard Ethernet + RDMA verbs.

Requires lossless Ethernet (PFC).

Compatible with IB verbs.

RoCE v2 stackEthernet fabric400/800Gb switchPFClossless configRDMA verbssame as IBMeta + Google use RoCE at scale; requires careful PFC + ECN tuning
RoCE v2.
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How it works end to end

PFC: priority flow control.

ECN: congestion notification.

DCQCN algorithm for congestion.

Meta + Google use at scale.