VRing: a case for building application-layer multicast rings (rather than trees)

The paper presents the design, analysis and performance evaluation of VRing, a novel application-layer multicast (ALM) protocol that establishes a virtual ring as an overlay network among the multicast group members in a self-organizing and distributed manner. In order to reduce the routing delay of the ring overlay network, we propose to form a spare ring overlay structure that improves connectivity among group members. The design of the spare ring is justified by proposing, and analytically studying, the performance of a data delivery and duplicate suppression mechanism that makes use of both the original ring and the spare ring for forwarding data packets. We conduct simulations of both VRing and a hierarchical ALM protocol, NICE, using the J-Sim network simulator Simulation results show that, although VRing has a higher path stretch and a higher link stress than NICE, it provides less control overhead, consumes less bandwidth, and provides lower average node degree than NICE. Furthermore, VRing achieves a higher average data delivery ratio in the presence of failures than NICE. The performance improvement is especially pronounced for larger multicast groups.