Enhancing scalability of tree-based reliable multicast by approximating logical tree to multicast routing tree

Tree-based approach has been proven to be most scalable for one-to-many rel iable multicast. It efficiently combines distributed recovery with local re covery over a logical tree of the sender and receivers. It has also been kn own that the performance of the tree-based protocols heavily depends upon t he quality of the logical tree. In this paper, we propose an end-to-end sch eme to further enhance the scalability of the tree-based approach. By excha nging packet loss information observed at the end hosts, the scheme constru cts and maintains a logical tree congruent with the underlying multicast ro uting tree even in the presence of session membership and multicast route c hanges. The scheme also groups the tree nodes and assigns separate multicas t. addresses to them in order to enable efficient multicast retransmission for reducing both delay and exposure. We compare the proposed scheme with T ree-based Multicast Transport Protocol (TMTP), a static tree-based protocol . Extensive simulations up to 300 node sessions reveal that the proposed sc heme reduces implosion and exposure more than 20% and 50%, respectively. Th e results also indicate that the scheme is highly scalable such that the im provement gets more significant as the size of the session increases.