Analysis of Hybrid Router-Assisted Reliable Multicast Protocols in Lossy Networks

Router-assisted concepts have been proposed in many research areas including reliable multicast protocols. These concepts can limit the implosion and repair locality problems in an effective way by attributing the role of repair locality to the specific router close to the point of packet loss. Several router-assisted reliable multicast protocols have been proposed in the literature. However, the extent of the reliability benefit of combining sender-initiated and receiver-initiated protocol classes is not known. This paper quantifies the reliability gain of combining classes for reliable multicasting in lossy networks. We define the delivery delay, the bandwidth consumption, and the buffer requirements as the performance metrics for reliability. We then use simulations to study the impact of multicast group size and loss rate on the performance of combining protocol classes. Our numerical results show that combining classes significantly improves the delivery delay, reduces the consumption of the network bandwidth and minimizes the buffer size at the routers compared to receiver-initiated class alone. The performance gains increase as the size of the network and the loss rate increase, making the combination of classes approach more scalable with respect to these parameters.