Mobile Group Communication

Abstract

This document discusses mobility extensions to current IP layer multicast solutions. Problems arising from mobile group communication in general, in the case of multicast listener mobility and for mobile Any Source Multicast as well as Source Specific Multicast senders are documented subsequently. General aspects of multicast distribution trees are derived. The principal approaches to multicast mobility are introduced along with sample solutions as presented to the IETF. Special focus is dedicated on Source Specific Multicast (SSM) senders. We propose extensions to multicast routing for transforming (morphing) previous delivery trees into optimal trees rooted at a relocated source. This extension scheme only requires basic signaling mechanisms, explicit joins and prunes, which are present in current multicast routing protocols such as PIM-SM. First evaluations grounded on real-world Internet topologies indicate network performance superior to traditional distribution schemes. An evaluation of future trends finalizes this paper.