Space-memory-memory Clos-network switches with in-sequence service

Clos-network switches have attracted a lot of attention because of their modularity and scalability. However, out-of-sequence problems weigh heavily against the application of buffered Clos-network switches. A space-memory-memory (SMM) Clos-network switch is proposed in this study which is able to provide in-sequence service. There are two features in the proposed switch which are different from the previously proposed schemes. First, two-stage load-balanced Birkhoff-von Neumann (LB-BvN) switches are adopted for each second-stage module. Second, no inter-stage matching is needed. The key idea to provide in-order cell delivery in the proposed SMM Clos-network switch is that cells belonging to the same flow will experience the identical delay when passing through the LB-BvN switches at the second stage, and arrive at their destined third-stage module in order. Each switching module operates independently, which makes the proposed SMM Clos-network switch practical to implement in hardware. Simulations show that the proposed switch can achieve high performance under both Bernoulli and Bursty arrival traffic.