Design and Analysis of Scheduling Algorithms for Optically Groomed Data Center Networks

Abstract

Data center networks generate high volumes of traffic. In order to reduce packet latency, packet transmissions are often centrally scheduled. Such approaches have been proposed for both packet-switched and hybrid optical-packet switched networks. This paper investigates algorithm design choices for transmission scheduling in a tightly synchronized hybrid optical packet data center network. This problem is studied in two cases: with precedence where the requests are scheduled in the order of arrival, and without precedence, where the requests can be reordered in time. It is shown that the problem without any precedence constraints is NP-complete. For scheduling with precedence constraints, a greedy algorithm is proposed and shown to be optimal. Theoretical approximation for the performance of scheduling with the greedy algorithm is presented. Simulation experiments were performed on a two-tier network with 1024 servers and 64 wavelengths. Parallel implementation aspects of the scheduling algorithm are also discussed.