The impact of scaling on a multimedia connection architecture

As the last two meetings of the Internet Engineering Task Force have shown, the demand for Internet teleconferencing has arrived. Packet audio and video have now been multicast to approximately 170 different hosts in ten countries, and for upcoming meetings the number of remote participants is likely to be substantially larger. Yet the network infrastructure to support wide-scale packet teleconferencing is not in place. These experiments represent a departure from the two- to ten-site telemeetings that are the norm today. They represent an increase in scale of multiple orders of magnitude in several interrelated dimensions.This paper discusses the impact of scaling on our efforts to define a multimedia teleconferencing architecture. Three scaling dimensions of particular interest are: (1) very large numbers of participants per conference, (2) many simultaneous teleconferences, and (3) a widely dispersed user population. Here we present a strawman architecture and describe how conference-specific information is captured, then conveyed among end systems. We provide a comparison of connection models and outline the tradeoffs and requirements that change as we travel along each dimension of scale. In conclusion, we identify five critical needs for a scalable teleconferencing architecture.