Performance analysis of access protocols for multi-level optical WDM MANs using wavelength routing switch

The problem of formulating a suitable access protocol for hierarchically designed optical wavelength division multiplexed (WDM) metropolitan area networks (MANs) is studied. The proposed network uses a two level hierarchy. Groups of nodes, located nearer to each other, are inter-connected through passive optical broadcast stars, which represent level-0 clusters. These level-0 clusters are connected to each other through an active wavelength routing switch (WRS). We consider a slotted-ALOHA based access protocol for both intracluster and intercluster communications and evaluate the performance of the proposed protocol in terms of network throughput and delay. Our study reveals that, even for such a simple protocol, WRS enhances the throughput of the system considerably with respect to the passive star-on-star configuration