Policy and Scope Management for Multicast Channel Announcement

Abstract

A scalable multicast session announcement system is a key component of a group communication framework over the Internet. It enables the announcement of session parameters (like the {source address; group address} pair) to a potentially large number of users, according to each site administrator's policy. This system should accommodate any flavor of group communication system, like the Any-Source Multicast (ASM) and Source-Specific Multicast (SSM) schemes. In this paper we first highlight the limitations of the current Session Announcement Protocol (SAP) and study several other information distribution protocols. This critical analysis leads us to formulate the requirements of an ideal multicast session announcement system. We then introduce a new session announcement system called Reflector. It appears as a hierarchical directory system and offers an effective policy and scope control technique. We finally mention some design aspects, like the protocol messages and configuration structures the Channel Reflector uses.