A routing protocol for anycast messages

An anycast packet is one that should be delivered to one member in a group of designated recipients. Using anycast services may considerably simplify some applications. Little work has been done on routing anycast packets. in this paper, we propose and analyze a routing protocol for anycast message. It is composed of two subprotocols: the routing table establishment subpro tocol and the packet forwarding subprotocol. In the routing table establish ment subprotocol, we propose four methods (SSP, MIN-D, SET, and CBT) for en forcing an order among routers for the purpose of loop prevention. These me thods differ from each other on information used to maintain orders, the im pact on QoS, and the compatibility to the existing routing protocols. In th e packet forwarding subprotocol, we propose a Weighted-Random Selection (WR S) approach for multiple path selection in order to balance network traffic . In particular, the fixed and adaptive methods are proposed to determine t he weights. Both of them explicitly take into account the characteristics o f distribution of anycast recipient group while the adaptive method uses th e dynamic information of the anycast traffic as well. Correctness property of the protocol is formally proven. Extensive simulation is performed to ev aluate our newly designed protocol. Performance data shows that the loop-pr evention methods and the WRS approaches have great impact on the performanc e in terms of average end-to-end packet delay. In particular, the protocol using the SET or CBT loop-prevention methods and the adaptive WRS approach performs very close to a dynamic optimal routing protocol in most cases.