Exploiting Idle Resources in a High-Radix Switch for Supplemental Storage

A general-purpose switch for a high-performance network is usually designed with symmetric ports providing credit-based flow control and error recovery via link-level retransmission. Because port buffers must be sized for the longest links and modern asymmetric network topologies have a wide range of link lengths, we observe that there can be a significant amount of unused buffer memory, particularly in edge switches. We also observe that the tiled architecture used in many high-radix switches contains an abundance of internal bandwidth. We combine these observations to create a new switch architecture that allows ports to stash packets in unused buffers on other ports, accessible via excess internal bandwidth in the tiled switch. We explore this architecture through two use cases: end-to-end resilience and congestion mitigation. We find that stashing is highly effective and does not degrade network performance.