Aggregated multicast: an approach to reduce multicast state

IP multicast suffers from a scalability problem with the number of concurrently active multicast groups because it requires a router to keep the forwarding state for every multicast tree passing through it and the number of forwarding entries grows with the number of groups. In this paper, we propose an approach to reduce the multicast forwarding state. In our approach, multiple groups are forced to share a single delivery tree. We discuss the advantages and some implementation issues of our approach, and conclude that it is feasible and promising. We then propose metrics to quantify state reduction and analyze the bounds on state reduction of our approach. Finally, we use simulations to verify our analytical bounds and quantify the state reduction. These initial simulation results suggest that our method can reduce multicast state significantly.