Choosing the set of rendezvous points in shared trees minimizing traffic concentration

In the current Internet there are two main types of intra-domain multicast routing protocols: dense mode and sparse mode. Dense mode protocols construct shortest path trees from a sender to receivers while sparse mode protocols construct shared trees rooted at a certain router, called core or RP (rendezvous point), to which all senders of a certain group send their packets in order to be transmitted to all receivers along such shared tree. These kinds of trees are well suited for wide-area networks, because we are sending information only to interested receivers and we maintain the same routing state for each group, independently of the number of senders, and only on the routers along the shared tree. While solving important scalability problems, such trees bring other drawbacks; mainly traffic concentration and delay. In current standards, PIM-SM (Estrin, Farinacci, Helmy, Thaler, Deering, Handley, Jacobson, Liu, Sharma, Wei, 1998) and CBT (Ballardie, 1997), no algorithms are specified to choose such RPs. In this paper, we present an approach to select the best set of RPs that minimizes traffic concentration while limiting the maximum delay.