A Highly Scalable LLM Clusters with Optical Interconnect

TL;DR

This paper proposes a novel physical topology design for optical circuit switch clusters, called Cross Wiring, which optimizes logical compatibility, scalability, and polynomial-solvability, verified through experiments and simulations.

Contribution

It introduces a new topology design approach using Symmetric Integer Matrix Decomposition and presents Cross Wiring as a practical implementation.

Findings

Cross Wiring achieves high scalability and compatibility.

Experimental results validate the effectiveness of the topology.

Simulations show improved performance over existing designs.

Abstract

Recent years have witnessed the adoption of optical circuit switch (OCS) technology. How to design the physical topology, defined by the physical wiring between electrical switching equipments and the OCS, is fundamental to designing efficient OCS-based clusters. We identify three features to evaluate the quality of a physical topology design: logical topology compatibility, cluster scalability, and topology engineering polynomial-solvability. However, none of existing physical topologies has achieved these three features simultaneously. This paper explores designing an optimal physical topology that simultaneously maximizes all. We begin by analyzing the importance of these features in OCS-based cluster and examine the limitations of current designs. Leveraging a proposed \emph{Symmetric Integer Matrix Decomposition Theorem}, we outline a general approach for designing optimal physical topologies and introduce \textbf{Cross Wiring} as a concrete instantiation. The feasibility and advantages of Cross Wiring are verified through a 128-NPU testbed and large-scale real-trace-based simulations.