AQoSM: Scalable QoS multicast provisioning in Diff-Serv networks
The deployment of IP multicast support is impeded by several factors among which are the state scalability problem, the cumbersome management and routing, and the difficulty of supporting QoS. In this paper, we propose an architecture, called Aggregated QoS Multicast (AQoSM), to provide scalable and efficient QoS multicast in Diff-Serv networks. The key idea of AQoSM is to separate the concept of groups from the concept of distribution tree by ''mapping'' many groups to one distribution tree. In this way, multicast groups can now be routed and rerouted very quickly by assigning different labels (e.g., tree IDs) to the packets. Therefore, we can have load-balancing and dynamic rerouting to meet QoS requirements. In addition, the aggregation of groups on fewer trees leads to routing state reduction and less tree management overhead. Thus, AQoSM enables multicast to be seamlessly integrated into Diff-Serv without violating the design principle of Diff-Serv of keeping network core ''QoS stateless'' and without sacrificing the efficiency of multicast. Finally, efficient resource utilization and strong QoS support can be achieved through statistical multiplexing at the level of aggregated trees. We design a detailed MPLS-based AQoSM protocol with efficient admission control and MPLS multicast tree management. By simulation studies, we show that our protocol achieves significant multicast state reduction (up to 82%) and tree maintenance overhead reduction (up to 86%) with modest (12%) bandwidth overhead. It also reduces the blocking ratio of user requests with strong QoS requirements due to its load balancing and statistical multiplexing capabilities.