Despite the marketing hype that would have you believe that ATM is a prerequisite for interactive network voice and video, there has been successful, large scale, interactive conferencing happening on the Internet since 1991. The main conferencing infrastructure, the MBone, currently has roughly 50,000 users spread over 3000 networks, 38 countries, and all 24 timezones.
This tutorial will give a brief introduction to the protocols of
cicuit-based conferencing (e.g., H.320 for ISDN and ATM) and
describe some of their problems and limitations. It will
describe the building blocks of Internet conferencing -- IP
multicast and Lightweight Sessions -- and show how they avoid
the problems inherent in the circuit based model. It will
describe the content and rationale behind the draft standard
protocols for Internet conferencing, RTP and SDP. It will then
take a fairly detailed walk through the main tools currently
used for Internet conferencing, vat (audio), vic (video) and wb
(shared workspace / whiteboard), describing the algorithms and
design issues of each. Finally there will be a brief discussion
of current research in this area and what the future might hold.
Lecturer
Van Jacobson is staff scientist at Lawrence Berkeley Laboratory and
heads LBL's Network Research Group. For the past decade he has been
working on various issues in the evolution of the Internet, including
TCP congestion control, gateway traffic management, network support
for "real time" traffic, and developing tools to allow interactive
conferencing over the Internet. He is a co-author of the RTP and SDP
standards and of the vat, vic, wb and sd conferencing tools.