A Viable Solution for Large Scale Multicast Support

In this work, we propose a Two-tier OverlayMulticast Architecture (TOMA) to provide scalable and efficient multicast support for a variety of group communication applications. In TOMA, Multicast Service Overlay Network (MSON) is advocated as the backbone service domain, while end users in the access domains form a number of small clusters, in which an application-layer multicast protocol is used for the communication between the clustered end users. Our two-tier architecture is able to provide efficient resource utilization with less control overhead, especially for large-scale applications. It also alleviates the forwarding state scalability problem and simplifies multicast tree construction and maintenance when there are large numbers of groups ongoing in the networks. We conduct simulation studies and the preliminary results demonstrate the promising performance of TOMA. Currently, we are in the process of implementing TOMA in a commercial on-line audio/vedio communication system, iVisit, to check the feasibility of TOMA and to further investigate its performance in real environments.