Construction of Application-Layer Multicast Trees for Message Distribution

This paper considers the problem of constructing minimum-delay multicast trees for message dissemination in overlay networks in which nodal delays for processing messages are taken into account in addition to communication delays. The objective is to find a multicast tree to deliver a message from a source to multiple destinations in minimum delay time. This paper introduces a new delay measure called reception-and-processing delay that takes nodal processing delays into account for constructing multicast trees. In the process of constructing a multicast tree, the branches of the multicast tree may intersect or overlap with each other. An efficient method is devised to avoid this undesirable phenomenon. Several heuristic algorithms are developed for constructing multicast trees. The performances of the heuristic algorithms are studied via simulation. Our simulation results show that constructing the multicast tree by iteratively attaching the destination node with the smallest reception-and-processing delay to the current multicast tree yields the lowest average multicast delay among the heuristic algorithms studied in this paper.