Layered transmission and caching for the multicast session directory service
Andrew Swan, Steven McCanne, Lawrence A. Rowe · 1998
The recent advent of the Internet hfulticast service has enabled a number of .mccessfulreal-time multimedia applications, yet the scalabii@ of these applications remains challenged by the inherent heterogeneity of the underlying Internet.One promisiig approach for taming this heterogene ity is to encode each media flow as a layered signal that is striped across multiple.multicast groups, thereby allowing a receiver to tune its individual reception rate by modulating its subscription to multicast groups.Though significant progress had been made on media transport protocols and congestion control strategies for adjusting multicast groups in this fashio~comparatively little work has been devoted to extending the session directory service and address allocation architecture to meet the needs and requirements of layered media.Moreover, the large-scale deployment of layered media formats is hindered by the lack of support for layered formats in existing session directory tools.To overcome these limitations, we propose a new architecture for session advertisement and caching that exploits multicast "admbistrative scope" through protocol proxies to admit layered media formats and reduce the start-up latency of a directory-stice client by an order of magnitude or more.Our architecture is fully compatible with the existing directory service allowing our implementation, -which is split acro.w a new session directory tool and network proxy, to be incrementally deployed within the current Internet multimedia conferencing architecture.