Design of switches with reconfiguration latency

Optical switching fabrics (OSF) are considered to be appealing solutions for the design of high speed packet switches, due to their excellent scalability in terms of bandwidth and power consumption. Candidate technologies are MEMS, bubble switches, broadcast-and-select networks with tunable devices. All of them suffer a reconfiguration latency each time the input/output connections are changed, due to technological constraints; unfortunately, this latency is not negligible with respect to the packet transmission time, and can adversely affect performance, especially delay and throughput. When scheduling the transmission of packets across an OSF, the multi-hop approach was shown to be a promising way to control the tradeoff between delay and throughput. In this case, the OSF is configured just once in a while, on a time scale much larger than the packet transmission time, and packets may be recirculated across the ports to provide full or partial connectivity among ports. Previous works have investigated this approach when a physical ring topology is used for the interconnection. Here, we extend the multi-hop approach to multidimensional regular topologies, which offer a better tradeoff between throughput and delay. We discuss not only the scheduling problem for these topologies, but also the design of routing. We investigate performance by simple analytical models and show the design tradeoff among throughput, speedup and delays.