A QoS multicast routing protocol for resource-intensive groups

The emergence of new multimedia group-based applications drives the need for efficient network support for quality of service (QoS) multicasting. In the core based tree (CBT) multicast distribution model, when a new receiver joins the group, it always attempts to establish a path to the core node of the multicast tree, making the core the hot spot node in the network. The situation becomes even worse when many groups have the same node as their core. Hence, the network resources around the core become the bottleneck for future join requests. Thus, the CBT-based protocols suffer from the problem of "hot spot traffic concentration" around the core. We propose a single-probe multi-destination (SPMD) protocol for QoS multicasting, which aims at alleviating the traffic concentration around the core. In our protocol, a receiver joining an existing multicast session establishes a path by performing a single path search towards multiple members of the multicast tree, rather than to the core node alone as in the case of CBT. We demonstrate the effectiveness of the proposed SPMD routing protocol through extensive simulation studies by evaluating its performance in terms of average call acceptance rate (ACAR) and average call setup time (ACST). Our studies show that the proposed protocol performs better than the single-destination multicast routing protocols (in terms of ACAR), especially when the groups are resource-intensive, such as high bandwidth groups.