Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. Wehave developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group. Our Protocol Independent Multicast (PIM) architecture: (a) maintains the traditional IP multicast service model of receiver-initiated membership; (b) can be configured to adapt to different multicast group and network characteristics; (c) is not dependent on a specific unicast routing protocol; and (d) uses soft-state mechanisms to adapt to underlying network conditions and group dynamics. The robustness, flexibility, and scaling properties of this architecture make it well suited to large heterogeneous inter-networks.

Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. We have developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group. Our Protocol Independent Multicast (PIM) architecture: a) maintains the traditional IP multicast service model of receiver-initiated membership; b) can be configured to adapt to different multicast grou...

This paper addresses the problem of constructing multicast trees with reservation of resources. The main features of the approach described are that it tolerates asymmetric traffic loads on network links and algorithmically locates data distribution centers for every multiparticipant interaction. A fast and scalable algorithm for locating distribution centers based on the network load and a priori knowledge of participant's locations and resource requirements is given. To explicitly handle cases of disjoint send and receive paths between two nodes, a protocol to build separate send-trees and receive-trees around the centers located in the above manner is given. Simulation results on various topologies are presented showing that, with the above center location mechanism, center-specific trees yield lower tree cost than source-specific trees for many concurrent senders with only a modest increase in the average path length. The use of distribution centers, a priori information, and sensi...