Multicast Access Protocols in an Optical Burst Switched WDM Ring Network

Abstract

Optical metropolitan area networks are commonly implemented in a ring architecture. In this research, we study various access protocols for multicasting in an optical burst switched (OBS) WDM ring environment. To our knowledge, this is the first detailed study of multicast protocols in an OBS ring architecture. A ring topology is appropriate for multicasting since routing is significantly simplified as compared to a mesh topology. This allows us to forgo complex routing algorithms and focus on performance of various access protocols. We have developed multicast access protocols that use simple scheduling and coordination schemes, and therefore are easy to implement in hardware. We consider only distributed protocols to avoid having a single point of failure. We study reliable versus unreliable protocols, and collision versus collision-free protocols. Ring nodes are equipped with a single fixed transmitter and tunable receiver (FT-TR). Signaling is done via a dedicated control wavelength. The performance of the multicast access protocols is analyzed by simulation. We measure the performance of the access protocols in terms of throughput, delay, channel utilization, and fairness. We show that there is a relationship between throughput, delay, and channel utilization. Specifically, throughput and delay performance can be increased at the expense of higher channel utilization. One of the proposed protocols, named Unicast Token, has high channel utilization, but performs well in terms of throughput, delay, and fairness.