MPLS Based Approach for Heterogeneous and Scalable Multicast in DiffServ

Efficient delivery of real-time multicast applications requires quality of service (QoS) support from the underlying network. The differentiated services (DiffServ) approach is a scalable way to provide QoS for theses applications. However, integrating native IP multicasting with differentiated services IP network is a quite complex issue. First, the multicast state scalability problems arises since it is required that each router have to keep a forwarding state for each multicast tree passing through it. Therefore, the number of forwarding states grows with the number of multicast groups. Second, another main difficulty with IP multicasting is handling heterogeneous QoS requirements within the same multicast group. In this paper, we propose a new approach in order to solve multicast scalability problem and to provide heterogeneous QoS to multicast groups using MPLS labels aggregation and dynamic DSCP. The complexity of the algorithm used to forward packets using the proposed approach is reduced from O(M) to O(1) where M is the number of multicast sessions. Consequently the router´s complexity (required memory and time processing) is optimized and thus the total packets processing delays are considerably reduced