A hierarchical overlay multicast network

Overlay multicast has drawn a lot of attention as an alternative to IP multicast. In the recently proposed overlay multicast solution, most of the implementations do not address the inter-domain administrative issue. For wide area multicast, it is unavoidable to have communication among several administrative domains. At this time, multicast routing cannot assume the knowledge of the global network topology, nor can it ignore the routing policy constrained by contractual commercial agreement between administrative domains. This problem can be solved by an hierarchical organization of the routing infrastructure. We propose a zone approach to overlay multicast that performs hierarchical routing on two levels - one level for within each of the administrative domains and another level for among the domains. We compare a single centralized routing to our zone-approach routing for overlay multicast and demonstrate that the performance penalty for the hierarchical organization of routing is small. The results have shown that our distributed design can achieve very close performance to the centralized algorithm. At the same time it enables the composition of different administrative networks, each with its own independent multicast protocol and administrative policy.