Executive Summary
OpenAI, in collaboration with AMD, Broadcom, Intel, Microsoft, and NVIDIA, has developed and released the Multipath Reliable Connection (MRC) protocol. Delivered as a specification through the Open Compute Project (OCP), MRC is a new networking protocol designed to improve the performance and resilience of large-scale AI training clusters. The protocol addresses key challenges like network congestion and link failures by spreading data transfers across hundreds of paths, enabling microsecond-level rerouting around failures and simplifying network design.
Key Takeaways
* Protocol Name: Multipath Reliable Connection (MRC).
* Core Function: MRC sprays packets from a single data transfer across hundreds of network paths simultaneously, which improves load balancing and fault tolerance.
* Microsecond Fault Tolerance: The protocol can detect network failures or congestion and reroute traffic in microseconds, minimizing interruptions to synchronous training jobs that are highly sensitive to delays.
* Simplified Network Design: MRC utilizes IPv6 Segment Routing (SRv6), allowing the sender to specify the exact path a packet travels. This eliminates the need for complex dynamic routing protocols like BGP, reducing a potential source of failure.
* Enables Multi-plane Topologies: The protocol is designed for multi-plane networks where a single high-speed interface is split into multiple lower-speed parallel networks. This increases path diversity, lowers costs, and reduces power consumption.
* Availability: The MRC specification is now available through the Open Compute Project (OCP) for industry-wide adoption. It is already deployed in OpenAI's largest NVIDIA GB200 supercomputers.
Strategic Importance
By open-sourcing MRC, OpenAI is standardizing a critical component of the AI infrastructure stack, aiming to unblock a key bottleneck in scaling AI models and fostering a broader ecosystem for building more efficient and resilient supercomputers.