A Randomized Error Recovery Algorithm for Reliable Multicast

An efficient error recovery algorithm is essential for reliable multicast in large groups. Tree-based protocols (RMTP, TMTP, LBRRM) group receivers into local regions and select a repair server for performing error recovery in each region. Hence a single server bears the entire responsibility of error recovery for a region. In addition, the deployment of repair servers requires topological information of the underlying multicast tree, which is generally not available at the transport layer. This paper presents RRMP, a randomized reliable multicast protocol which improves the robustness of tree-based protocols by diffusing the responsibility of error recovery among all members in a group. The protocol works well within the existing IP multicast framework and does not require additional support from routers. Both analysis and simulation results show that the performance penalty due to randomization is low and can be tuned according to application requirements.