Performance Analysis of an Enhanced Distributed Access Mechanism in a Novel Multiservice OPS Architecture

Optical Packet Switching (OPS) technologies are among the most promising solutions for next generation Internet. In this paper, we address quality of service (QoS) and fairness issues in a novel OPS ring architecture with a slotted synchronous transmission mode. The basic MAC protocol in the studied architecture is similar to the CSMA/CA mechanism. Using this mechanism, each node in the network may use the available bandwidth in an opportunist manner. Moreover, in the considered network, optical packets bypass intermediate nodes without being delayed or converted to the electronic domain. Therefore, the chances for a ring node to find available transmission resources are tightly correlated to the matrix of traffic of the other nodes. This leads to unfair sharing of the transmission medium. In order to remedy this problem, we elaborate a distributed tag-based enhanced access mechanism (TEAM). The proposed solution evolves from two preemptive access mechanisms that we have proposed recently (namely the packet erasing mechanism PEM and the extraction and reemission mechanism ERM). In order to resolve the unfairness issue, which characterizes ring OPS architectures with transparent transit at intermediate nodes, we use an advanced distributed approach where all ring nodes cooperate together. Finally, we evaluate the performance of the TEAM mechanism through several simulation scenarios.