A combined group/tree approach for scalable many-to-many reliable multicast

In this paper, we present the design, implementation, and performance analysis of Group-Aided Multicast (GAM), a scalable many-to-many reliable multicast transport protocol. It achieves high quality ACK trees while keeping the tree maintenance overhead reasonably low in the presence of dynamic group membership and route change. The proposed scheme is supported by a group configuration mechanism that organizes the members in a multicast session into multiple small groups and a tree configuration mechanism that maintains the logical trees according to the underlying multicast routing trees. With the two mechanisms, it builds a two-layer hierarchy of multi-level logical trees from which high-quality per-source ACK trees are generated. Simulation results show that the proposed protocol is more scalable than an existing protocol in terms of processing time for request/repair messages and recovery latency.