Multicast State Balancing By Using Alternate Shortest Paths

Abstract — The lack of resources in routers will become a crucial issue with the deployment of state storing protocols such as QoS or multicast ones. In particular, single or any source multicast protocols will most probably take over resources up to their limits for maintaining multicast tree information. The aim of this paper is to study the possibility and benefit of using multiple shortest paths in order for a new member to reach a multicast tree. Such a mechanism would not reduce the overall amount of state information in the network but it would distribute this amount more evenly among all routers. The idea is to use an alternate shortest path provided by the underlying unicast routing protocol to avoid a saturated router, that is a router that can not or does not want to store any more multicast state information. As the simulation results are very sensitive to the topology used, we have used as input topology a real public Internet map. We have then simulated our multipath-aware join mechanism upon samples of this map. We have found that depending on the tree size, the use of our mechanism can increase successful join attempts by up to 55 % when the network is half saturated. I