The evolution of multicast: From the MBone to interdomain multicast to Internet2 deployment

Multicast communication - the one-to-many or many-to-many delivery of data - is a hot topic. It is of interest in the research community, among standards groups, and to network service providers. For all the attention multicast has received, there are still issues that have not been completely resolved. One result is that protocols are still evolving, and some standards ore not yet finished. From a deployment perspective, the lack of standards has slowed progress, but efforts to deploy multicast as an experimental service are in fact gaining momentum. The question now is how long it will be before multicast becomes a true Internet service. The goal of this article is to describe the past, present, and future of multicast. Starting with the Multicast Backbone (MBone), we describe how the emphasis has been on developing and refining intradomain multicast routing protocols. Starting in the middle to late 1990s, particular emphasis has been placed on developing interdomain multicast routing protocols. We provide a functional overview of the currently deployed solution. The future of multicast may hinge on several research efforts that are working to make the provision of multicast less complex by fundamentally changing the multicast model. We briefly survey these efforts. Finally, attempts are being made to deploy native multicast routing in both Internet2 networks and the commodity Internet. We examine how multicast is being deployed in these networks.