Adaptive Hybrid Multicast with Partial Network Support

In this paper, we propose a new multicast scheme, PAM, which as opposed to native IP multicast, does not require all routers to be IP multicast-enabled, and as opposed to existing application-level multicast, does not exclude network support. Instead, PAM relies on partial network support, selects a small subset of routers as PAM-enabled multicast routers that are strategically located to serve group communication, and adapts its selection based on group dynamics. As a result, PAM (1) is suitable for both sparse and dense communication groups, (2) can reduce the network overhead inherent in native IP multicast, and (3) does not suffer the delay stretch and the high stress inherent in application-level multicast. Experimental results on both synthetic and realistic Internet topologies, for both sparse and dense groups, reveal that PAM can achieve efficient group communication with no delay stretch, an average stress of merely 1.25, while using less than 15% of the multicast routers that are needed in native IP multicast.