This is a joint effort with Deborah Estrin, University of Southern California under award NCR-9628729. Many applications require reliable multipoint data delivery. Some well known examples are netnews, electronic mailing list, and network routing protocols such as BGP. Up until now, however, due to the lack of widely available support for both IP multicast and reliable multicast transport, these applications have been using multiple TCP connections to achieve reliable data delivery to multiple destinations, which results in both poor scalability and inefficient utilization of network resources. The goal of this research is to develop a framework and a set of mechanisms to provide efficient, robust, scalable, and reliable multicast data delivery both over very large networks and with very large multicast groups. The basic principles that have guided the design include the application level framing (ALF), the IP multicast group concept and receiver-initiated group management, and the core design principles of TCP/IP --- simple datagram service, the end-to-end approach to reliability, and automatic adaptation to changing operational environment. The research will (1) systematically investigate the scaling issues with the proposed adaptive error recovery scheme; (2) develop mechanisms to localize error recovery traffic and substantially reduce the recovery overhead in the current design; (3) develop flow and congestion algorithms for many-to-many multicast data delivery; and (4) investigate new models for session message distribution to further improve the scalability.
