Abstract
Traditional IP multicast is likely to imply a huge burden of storage and forwarding for routers. Some issues, such as the scalability problem, will be aggravated when various classes of quality of service are fulfilled in multicast traffic. The recent proposed application layer multicast is more scalable but increases traffic load in network layers and end-to-end delivery delay. In this paper, we present a multicast protocol that supports comparable multi-class services over an overlay network where edge routers are multicast-aware and core routers are oblivious of multicast. The comparable multi-class services consist of different services required by multicast members which can be satisfied via the same delivery tree. Considering the multi-class services and resource limitation on routers, the problem of building minimum cost trees has been proven to be NP-hard. So, we design several feasible heuristic algorithms to solve it. Extensive simulations are conducted to evaluate the performance of the proposed heuristics, and validate the effectiveness of reducing the total tree cost and iteration times under considered constraints. The proposed method is expected to be combined with DiffServ or MPLS VPN networks to fulfill multi-class QoS overlay multicast.