Reliable multicast with B.I.E.R.

Inter-network multicast protocols, which build and maintain multicast trees, incur both explicit protocol signalling, and maintenance of state in intermediate routers in the network. Bit-indexed explicit replication (B.I.E.R.) is a technique which can provide a multicast service yet removes such complexities: intermediate routers are unencumbered by group management, and no per-group state is to be maintained. This paper explores the use of B.I.E.R. as a basis for developing an efficient and reliable multicast mechanism, where redundant traffic is avoided, essential traffic is forwarded along shortest paths, and no per-flow state is required in intermediate routers. Evaluated by way of both an analytical model and network simulation both in generic and in real network topologies with varying background traffic loads, the proposed B.I.E.R.-based reliable multicast mechanism exhibits attractive performance attributes: It attains delivery success rates as high as any other reliable multicast service, but with significantly better link utilisation and no per-flow or per-group state in intermediate routers of the network.