Improved Multicast Algorithm for Overlay Multicast in P2P Based Video Streaming

In this paper we introduce some significant improvements to a well known algorithm for multicast in overlay networks, namely ZigZag. The improvements are mainly related to a better handling of peer churn, avoiding service interruption to the subtree rooted at the departed node. Since the target is a video streaming service, additional constraints are related to a minimum serving quality for outgoing links. This translates in a maximum number of children for each node depending on its outgoing link capacity: to allow this, more realistic constraints on node heterogeneity are introduced so that the multicast tree is allowed to grow unbalanced. It is also shown that exploiting the overlapped control structure with scalable coded video it is possible to minimize service interruptions due to peers departure while minimizing signaling overhead. The changes have been implemented and validated using network simulator 2 to show the effectiveness of the procedures.