A Router-Based Congestion Control Scheme For Real-Time Continuous Media*

Many distributed multimedia applications require real-time network communication services to be effective. Although architectural models for real-time communication on the Internet are evolving (e.g., [2]), none appear to consider the problem of realizing real-time performance on existing local-area networks. This is important as the “first” and “last mile” of a network connection — the portion from a sending workstation to an Internet-bound router on the originating campus, and the portion from an inbound router to a receiving workstation on the destination campus — are likely to employ conventional LAN technologies that cannot reliably provide real-time service. We are investigating the problem of congestion control in a campus-area network. We advocate the placement of a set of simple, generic media adaptations into campus routers for the purpose of ameliorating the effects of congestion along the “first/last mile” of a connection. The adaptations and their implementation are designed to complement proposed schemes such as RSVP for real-time communication through the wide-area network. We demonstrate empirically that our router-based congestion control scheme is capable of supporting an effective, best-effort, real-time transmission service across congested campus networks.