Quality of Service and the End-to-End Argument

Audio-visual services are now commonly used on the Internet. Many of them are based on batch downloading of contents for later replay. Real-time interactive and streaming services are now rapidly becoming popular. These services would benefit from quality of service if it were widely provided. The purpose of this article is to show how QoS solutions may be introduced incrementally. Quality is obtained by means of a probe-based admission control that can be exerted outside the network. The introduction of QoS starts from self-admission control in the application layer, followed by transport layer service differentiation. These two steps do not require any change to the network. If motivated, scheduling for service class separation in the network may be added. We show by proof of concept how QoS may be provided in agreement with the end-to-end argument. The three steps of our proposal are compared and discussed with respect to the possibility of deployment.