Performance of a MAC Protocol for WDM Networks with On-Line Scheduling

This paper investigates the performance of media access protocols based on on-line scheduling for an optically connected star-coupled system with Wavelength Division Multiple Access channels. Hybrid access protocols combining reservation and pre-allocation of receiver channels have been recently proposed. Transmission consisted of a reservation phase followed by a data phase. Each node was allowed to place a reservation for one WDM channel. This protocol is extended in this paper by allowing reservations on multiple channels and using simple on-line scheduling algorithms. Existing scheduling algorithms (all are off-line) for similar reservation problems tend to have high implementation and computational complexity. We require that scheduling algorithms be real-time and amenable to hardware implementation. The performance of the extended protocol incorporating two simple on-line scheduling algorithms is presented in this paper. We show that the slight increased computational overhead with scheduling is justified by reduced packet latency and higher utilization, especially for client-server traffic.