Robust and efficient path diversity in application-layer multicast for video streaming

Application-layer multicast (ALM), as alternative to IP multicast, provides group communication without the need for network infrastructure support. To improve the reliability of ALM service, path diversity has been studied and two schemes to construct diverse paths for hosts are proposed. One is the random multicast forest (RMF) and the other is topology-aware hierarchical arrangement graph (THAG). RMF makes the paths from the media source to a participating host diverse by selecting parents for each host randomly, while THAG makes the paths node-disjoint by constructing multiple independent multicast trees, where any interior node in a multicast tree will be leaf node in all the other multicast trees. Topology-awareness is implemented in both schemes to make them efficient for media delivery. We compare the reliability and efficiency of THAG and RMF through extensive simulation. The results show that the reliability of THAG has been improved up to 20% compared with RMF. The efficiency metrics, such as relative delay penalty, link stress, and delay variation among different trees in THAG, are also smaller than or almost the same as that in RMF. The results indicate that THAG is a reliable and efficient ALM scheme for streaming media service.