An Intelligent Global Message Prioritization Algorithm for High-Performance Scheduling in WDM Star Networks

Abstract

In this article we propose the Minimization of Probability and Size of scheduling Latency (MinPSL) protocol for remarkably efficient load balancing and scheduling of variable length messages in WDM star networks. Our EMPS protocol has been shown to noticeably increase the performance of practical networks with non-uniform destinations and non-negligible transceiver tuning latencies, while other well-known schemes like EATS and MSL seem to suffer under these realistic conditions. EMPS tries to balance the offered load by only considering the heads of the message queues maintained by the source nodes. As a result, its performance is degraded, especially for medium to high offered loads and for rather slowly tunable transceivers. The proposed MinPSL scheme, on the other hand, examines each source node’s message queue up to a certain depth and assigns higher priorities to messages intended for the least used destinations. In this way, MinPSL perfectly minimizes the probability of having to schedule two or more messages intended for the same destination simultaneously or at close times. Furthermore, it also minimizes the actual performance penalty incurred, when scheduling of consecutive messages with the same destination cannot be avoided. Extensive simulations are carried out in order to study the performance of MinPSL and compare it to the EMPS scheme under various conditions. The simulation results ascertain the fact that the proposed MinPSL protocol always brings about a considerable performance improvement.