Throughput analysis of tree-based protocols for many-to-many reliable multicast

Tree-based reliable multicast protocols are known to be most scalable for one-to-many sessions. However, there is still an open question whether these protocols are also scalable for many-to-many sessions. We categorize existing tree-based protocols into four classes according to feedback/retransmission policies employed, and analyze and compare them based on a spatial loss model proposed in this paper. The proposed model considers the correlation of packet loss events for more realistic analysis unlike the previous work. The analysis reveals that in many-to-many cases, tree-based protocol with unicast NACK, unicast retransmission and periodic polling is most scalable with respect to throughput for practical session sizes. The protocol is also simple to implement.