COST-QUALITY TRADEOFFS IN THE INTERNET

The data delivery service currently offered in the Internet is a point -to-point best effort service. Work is underway in various IETF (Inter net Engineering Task Force) working groups to include new services for applications that require a specific quality of service. Examples of such applications include the so-called real-time applications such as audio and videoconferencing, distributed interactive simulation, etc. The cost in terms of network resources for providing these services i s higher than that for providing best effort service. Thus, the existe nce of new services presents a tradeoff between quality and cost. Furt hermore, recent work has shown that many real-time applications can ad apt their output rates (and hence their network resource requirements) depending on network conditions (and hence on the available network s ervice). Such tate adaptive applications present a further tradeoff be tween cost and quality of the data sent into the network.In this paper , we describe these tradeoffs and analyze their impact on the applicat ions and on the network. We illustrate our points with recent results and measurements obtained with IVS, which is a rate-adaptive audio and videoconference application for the Internet developed at INRIA.