# MetaRoCE: A New RDMA Transport Built for AI-Scale Ethernet

[Meta](https://yomu.fyi/company/meta) · By Arvind Srinivasan, Neil Spring, Omar Baldonado, Rajiv Krishnamurthy · Aug 24, 2026

## Summary

Scaling frontier AI training and inference across massive GPU clusters places severe demands on network fabrics, yet conventional RoCE relies on Priority Flow Control to enforce in-order packet delivery. Meta introduced MetaRoCE, a clean-sheet RDMA transport protocol engineered specifically for lossy, multiplane commodity Ethernet without requiring PFC. By shifting intelligence to endpoint NICs, the protocol sprays packets across fine-grained logical paths, writing out-of-order data directly into destination memory without reorder buffers or head-of-line blocking. Congestion is managed via per-path ECN windows paired with receiver-driven rate hints returned in acknowledgments. In validation on a 64-node AMD GPU cluster running collective operations, MetaRoCE outperformed RoCEv2, sustaining roughly 86% throughput under 1% packet loss and achieving linear scaling across multiplane fabrics.

## Takeaways

- MetaRoCE eliminates Priority Flow Control (PFC) and reorder buffers by enabling out-of-order packets to write directly to their target memory locations on arrival.
- Congestion management combines sender-driven ECN path windows with receiver-allocated bandwidth hints in acknowledgments, resolving network incast in one or two round trips.
- Cluster benchmarks across 4-plane and 8-plane topologies showed throughput scaling linearly with plane count while sustaining approximately 86% throughput during 1% packet loss.

**Tags:** [Architecture](https://yomu.fyi/topic/architecture), [Open Source](https://yomu.fyi/topic/open-source), [Performance](https://yomu.fyi/topic/performance), [Reliability](https://yomu.fyi/topic/reliability), [Scalability](https://yomu.fyi/topic/scalability)

[Read original post](https://engineering.fb.com/2026/08/24/networking-traffic/metaroce-rdma-transport-ai-ethernet)