Dynamic Reconfiguration of Optically Interconnected Networks with Time-Division Multiplexing

Routing performance of optical interconnection networks is limited by both switch complexity and network connectivity. One way to overcome these limitations is to allocate the network bandwidth in a time-division multiplexed (TDM) fashion. With this technique, an appropriate subset of input-to-output connections can be established during a time slot and all possible connections can be established over several time slots. Emulating a fully connected network, however, requires a large multiplexing degree, and thus introduces latencies which may be prohibitive. As a solution, we propose a technique called Reconfiguration with Time Division Multiplexing (RTDM). With RTDM, only a subset, as required by applications, of all possible connections needs to be multiplexed in the network by letting the network go through a sequence of configurations. Network reconfiguration with TDM can be done either statically or dynamically. Static RTDM is applied when communication requirements of an application are known a priori. This paper deals mainly with dynamic RTDM, which requires run time control to accommodate dynamic connection requests. We show that reconfiguration overhead can be amortized over a sequence of configurations. In particular, we describe how the complexity of a dynamic reconfiguration control algorithm can be reduced through pipelined processing of requests. Our simulations show that dynamic RTDM allows for fair and fast allocation of network resources to connection requests. As a result, network service time decreases and communication efficiency increases.