HyperCast - Towards Super-Scalable Multicast Communications

Jorg Liebeherr
Electrical Engineering Department
Polytechnic University


Multimedia collaborative applications for the Internet require the availability of multicast protocols that enhance the basic connectionless IP Multicast service. A critical requirement of such protocols is their ability to support a large group of simultaneous users. For this it is crucial that there exist mechanisms to efficiently exchange control information between the members of a group. In this paper, we present a new approach for distributing control information within a multicast group. The goal of our approach is to scale to very large group sizes (in excess of 100,000 users). Multicast group members are organized as a logical n-dimensional hypercube, and all control information is transmitted along the edges of the hypercube. We analyze the scalability of the hypercube control topology and show that the hypercube balances the load per member for processing control information better than existing topologies. We use actual data traces of the group membership in an MBONE conference to gain insight into the transient changes of the load at each node. We present a set of protocol mechanisms that maintain the hypercube topology in a soft-state fashion without requiring any entity to have global state information.

Luis Gravano