SEAM: Scalable and efficient ATM multicast

Abstract

This paper proposes a multipoint-to-multipoint multicast architecture for ATM networks. The necessity for such an architecture stems from the scalability requirements, both in terms of state to be maintained in the network and in terms of the group population dynamics, of a wide range of networking applications. We argue that approaches of using multicast servers or meshes of point-to-multipoint virtual circuits (VCs) may be inadequate solutions to this problem. We propose a true multipoint-to-multipoint architecture called SEAM, which uses a single VC for a multicast group consisting of multiple senders and receivers. We achieve this without changes to ATM's AAL5. SEAM relies on an additional switching feature we call cut-through forwarding, which enables the mapping of several incoming VCs into outgoing VCs. We believe that SEAM is both an important and necessary step in the evolution of ATM. It will enable applications relying on group multicast to benefit directly from ATM's quality of service support and scalable bandwidth and the resulting performance advantages. Also, it considerably simplifies the problem of supporting IP multicast over large ATM networks.