Efficient group coordination in multicast trees

The majority of today's Internet applications relies on point-to-point communication. In recent years, however, multipoint communication support has become the foundation for such applications as multiparty video conferencing, distributed interactive simulations, and collaborative systems. We describe a novel protocol to coordinate multipoint groupwork within the IP-multicast framework. The protocol supports Internet-wide coordination for large and highly-interactive groupwork, relying on the dissemination of coordination directives among group members across a shared end-to-end multicast tree. We also describe how addressing extensions to IP multicast can be used for our multisite coordination mechanism.