On supporting quality of service over the Internet

grantor: University of TorontoThe emergence of real-time applications has underscored the need to provide some forms of service quality in the Internet. Current discussions on quality of services (QoS), however, embrace different approaches and lack a unified definition. Until now, it is still questionable whether ubiquitous end-to-end QoS is possible in the Internet as its decentralised nature does not lend itself easily to implement homogeneous mechanisms for traffic differentiation. This thesis presents methods of delivering QoS in the Internet. It focuses on two main rudiments of QoS recently proposed by the IETF community: Integrated Services (Int-Serv) and Differentiated Services (Diff-Serv). In addition, it addresses several important issues which arise from supporting these QoS models over the Internet. For the Int-Serv model, the thesis proposes a fusion model that efficiently integrates the Int- Serv and RSVP into ATM. The architectural design, prototype implementation and experimental evaluation on the system performance are discussed. The results demonstrate an operational environment that efficiently facilitate the delivery of video over RTP/UDP/Int-Serv-IP/ATM. Furthermore, the thesis discusses a number of problems in supporting QoS given two unique characteristics of IP multicast: heterogeneity and any-point-to-any-point connectivity. Novel mechanisms, such as token forwarding and VC-merge capable scheduling, are developed. These mechanisms complement the design of a common ATM switch in the support of both multicast and scalability. Performance analysis of these mechanisms is also presented. For Diff-Serv, the thesis proposes a general feedback control extension to the current Diff-Serv framework. Based on this extension, an intra-domain flow control algorithm tailored for the network layer is developed. Our simulation analysis shows that the overall feedback controlled Diff-Serv can offer a significant improvement in resource sharing and utilisation. To justify the importance of this mechanism, the thesis also reviews the performance results and the trade-offs in terms of protocol overhead and complexity of the mechanism. While this thesis has addressed some of the important issues and provided several solutions, delivering QoS in the Internet involves many aspects of network design. The results presented in this thesis will serve as an important step towards better understanding of issues related to the support QoS over the Internet.Ph.D