Enabling conferencing applications on the Internet using an overlay multicast architecture

In response to the serious scalability and deployment concerns with IP Mult icast, we and other researchers have advocated an alternate architecture fo r supporting group communication applications over the Internet where all m ulticast functionality is pushed to the edge. We refer to such an architect ure as End System Multicast. While End System Multicast has several potenti al advantages, a key concern is the performance penalty associated with suc h a design. While preliminary simulation results conducted in static enviro nments are promising, they have yet to consider the challenging performance requirements of real world applications in a dynamic and heterogeneous Int ernet environment. In this paper, we explore how Internet environments and application require ments can influence End System Multicast design. We explore these issues in the context of audio and video conferencing: an important class of applica tions with stringent performance requirements. We conduct an extensive eval uation study of schemes for constructing overlay networks on a wide-area te st-bed of about twenty hosts distributed around the Internet. Our results d emonstrate that it is important to adapt to both latency and bandwidth whil e constructing overlays optimized for conferencing applications. Further, w hen relatively simple techniques are incorporated into current self-organiz ing protocols to enable dynamic adaptation to latency and bandwidth, the pe rformance benefits are significant. Our results indicate that End System Mu lticast is a promising architecture for enabling performance-demanding conf erencing applications in a dynamic and heterogeneous Internet environment.