Minimizing scheduling complexity with a Clos-network space-space-memory (SSM) packet switch

In this paper we propose a three-stage space-space-memory (SSM) Clos-network switch that uses crosspoint buffers in the third-stage modules to eliminate the need for performing multiple iterations in for port matching. We show that the proposed switch not only reduces the configuration complexity of space-space-space (S3) switches but also improves switching performance and relaxes configuration timing. We demonstrate these advantages by comparing the performance of the proposed switch using the weighted module-first no-port (WFM-NP) matching scheme to that of a S3 switch using the original scheduling scheme (with port matching). For higher utilization of the SSM switch, we propose the weighted central-module-link matching (WCMM) scheme. The WCMM scheme rescinds multiple iterations for module matching and yet, it achieves higher performance than the WFM-NP scheme. The advantages of the SSM switch are achieved without memory speedup. The memory addition is a small cost to trade for complexity reduction and performance improvement.