A scalable issue in multicast protocols: reducing forwarding states

Forwarding state explosion may cause a scalability problem in multicast protocols. In this paper we describe a technique, called dynamic overlap tree path (DOTP), to improve the scalability of existing multicast protocols. This technique, which can be incorporated in both the dense and sparse modes of multicast protocols, dynamically finds overlapped tree paths and merges their forwarding states to reduce the storage requirement in multicast routers without introducing any additional control-message overheads. Using the OPNET simulation package, we implemented some multicast protocols such as CBT and PIM and their modifications to investigate the efficiency of our proposed technique. According to the simulation, the overall average forwarding-state table size of the networks simulated can be reduced by about 30%.