New bandwidth and delay-constrained distributed multicast routing

Nowadays, many multicast QoS routing algorithms have low success ratio of routing when receivers QoS requirements are strict. This paper proposes a new bandwidth- and delay-constrained distributed multicast routing called QDMR (QoS-based Distributed Multicast Routing). QDMR uses RBMF(Reverse Best Metric Forwarding) instead of RPF ( Reverse Path Forwarding) in selecting path to in-tree routers. Query message is forwarded if and only if it travels from a path whose reverse route is a RBMP (Reverse Best Metric Path) from a new receiver to the current node. If RBMP's satisfy the new receivers QoS requirements, one of them with the smallest hop counts to the multicast tree will be selected as the branch connected to the existing multicast tree. At the end, simulation shows that QDMR improves success ratio of routing reasonably and reduces protocol overheads meanwhile.