Selection of candidate cores for core-based multicast routing architectures

A core based tree established by the core based tree multicast routing architecture (CBT), the protocol independent multicast-sparse mode (PIM-SM), or the core-manager based multicast routing (CMMR) is rooted at a center node called core or rendezvous point (RP). The routes from the core (or RP) to the members of the multicast group are shortest paths. The costs of the trees constructed based on the core and the packet delays are dependent on the location of the core. In existing core based multicast routing architectures (CBT, PIM-SM, and CMMR), the core for a multicast group is selected from a set of candidate cores. However, none of them suggests a method for selecting the set of candidate cores. We propose three methods for selecting the set of candidate cores. The three proposed methods are compared with a method which select the candidate cores randomly. Three performance measures, namely, tree cost, mean packet delay, and maximum packet delay are considered. Our results show that the three proposed methods produce lower tree cost and significantly lower mean packet delay and maximum packet delay than the method which selects the candidate cores randomly. One of the three proposed methods, namely, k-maximum path count method.