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

Abstract

Tree-based approach has been proven to be most scalable for one-to-many reliable multicast. It efficiently combines distributed recovery with local recovery over a logical tree of the sender and receivers. It has also been known that the performance of the tree-based protocols heavily depends upon the quality of the logical tree. In this paper, we propose an end-to-end scheme to further enhance the scalability of the tree-based approach. By exchanging packet loss information observed at the end hosts, the scheme constructs and maintains a logical tree congruent with the underlying multicast routing tree even in the presence of session membership and multicast route changes. The scheme also groups the tree nodes and assigns separate multicast. addresses to them in order to enable efficient multicast retransmission for reducing both delay and exposure. We compare the proposed scheme with Tree-based Multicast Transport Protocol (TMTP), a static tree-based protocol. Extensive simulations up to 300 node sessions reveal that the proposed scheme reduces implosion and exposure more than 20% and 50%, respectively. The results also indicate that the scheme is highly scalable such that the improvement gets more significant as the size of the session increases.