Near-optimal multihop scheduling in general circuit-switched networks

Abstract

Circuit switched networks with high-bandwidth links are essential to handling ever increasing traffic demands in today's data centers. As these networks incur a non-trivial reconfiguration delay, they are mainly suited for bursty traffic or large flows. To address the reconfiguration delay vs. high-bandwidth tradeoff in circuit networks, an essential traffic scheduling problem is to determine a sequence of network configurations to optimally serve a given traffic. Recent works have addressed this scheduling problem for one-hop traffic in fully-connected circuit networks. In this work, we consider the traffic scheduling problem in general circuit networks with multi-hop traffic load. Such a general model is essential for networks with indirect routes between some nodes, e.g., for recently proposed wireless optical (FSO-based) networks, or to allow multi-hop routes for load balancing. In this context, we develop an efficient algorithm that empirically delivers high network throughput, while also guaranteeing a constant-factor approximation with respect to an objective closely related to network throughput. We generalize our technique and approximation result to more general settings, including to the joint optimization problem of determining flow routes as well as a sequence of network configurations. We demonstrate the effectiveness of our techniques via extensive simulations on synthetic traffic loads based on published traffic characteristics as well as publicly available real traffic loads; we observe significant performance gains in terms of network throughput when compared to approaches based on prior work, and very similar performance to an appropriate upper bound.