Self organizing hierarchical multicast trees and their optimization

Multicast routing protocols suitable for wide-area networks are being developed for the Internet. Protocols based on hierarchical trees appear to be well suited for their superior scalability and flexibility. We show how to construct a class of hierarchical multicast trees and we analyze their performances. This study gives insight into how the chosen hierarchical structure impacts the tree performance with respect to network resource consumption. Optimal structures which minimize resource consumption are deduced, which allows for simple dimensioning rules, such as how many hierarchical levels should be used. A stochastic geometric approach turned out to be well adapted for this study. This approach leads to explicit expressions for the average tree cost, as a function of the hierarchical clustering, from which the optimal tree structure can then be easily deduced.