The breadcrumb forwarding service

Abstract

If ubiquitously deployed, IP Multicast promises to provide an efficient datagram service for an arbitrary sending host to reach an arbitrary and dynamic set of destination hosts anywhere in the Internet. Unfortunately, two very difficult problems ---interdomain multicast routing and viable end-to-end multicast transport--- have yet to be solved and deployed satisfactorily.This paper proposes that two existing but independent network mechanisms--- the EXPRESS service model and the network component of the Pragmatic Multicast protocol (PGM)--- be synthesized in a scheme we call the Breadcrumb Forwarding Service (BCFS) to simultaneously tackle the problems of interdomain multicast routing and end-to-end reliable multicast. Like EXPRESS, BCFS utilizes explicit-source group join and like PGM, enhances the network forwarding architecture with finer-grained group control. In this paper, we detail BCFS service model and router mechanisms to support the service. To demonstrate the flexibility and efficiency of BCFS, we describe the application examples built on this service model, which can accommodate not only PGM and also a novel reliable multicast transport protocol.