On the Multicast Scheduling Mechanisms for Interconnected WDM Optical Networks

In this paper, we first propose and compare various multicast scheduling protocols for an asynchronous WDM optical star network. A central traffic scheduler is allocated to coordinate message transmissions. The proposed scheduling schemes can be executed in real time and are conducted in two phases. The first phase is to search (through input queues) for a candidate multicast message that can be sent, without partition, to all of its intended recipients. The second phase efficiently partitions a multicast message into multiple transmissions, when phase 1 fails. Such an approach significantly improves channel and receiver utilization levels, thus effectively reducing the performance degradation caused by head-of-line blocking effects. To apply these mechanisms to a wider range of networking environments, we further consider an interconnected dual-star architecture and propose associated algorithms. By using a simple heuristic approach, these schemes are able to successfully exploit the inter data channels and properly utilize the wavelength reuse property of the intra data channels. Performance results have shown the merits of deploying the multicast algorithms in such an interconnected structure.