However, several issues need to be resolved before End System Multicast becomes a practical alternative to IP Multicast. A key concern is the performance penalty associated with such a model. We have studied this question in the context of a protocol we have developed called Narada . In Narada, end systems self-organize into an overlay structure using a fully distributed protocol. We have evaluated Narada using simulation and Internet experiments.
Preliminary results are encouraging.
In most simulations and Internet experiments, the delay and bandwidth penalty are low. We believe the potential benefits of repartitioning multicast functionality between end systems and routers significantly outweigh the performance penalty incurred. While we refer to end systems, it is with the understanding that this may easily be generalized to nodes at the edge of the network such as campus wide proxies and edge routers. Proxies can exploit native multicast available at the LAN level, have larger processing power than hosts, are better connected to the Internet and allow for organization level agreements. Further, they could potentially exploit temporal and spatial locality in group formations, At the other end of the spectrum, tree building mechanisms might be built into actual applications running on hosts, and could exploit application specific requirements and peculiarities.