Name: Ngin Hoon Tong Degree: Doctor of Philosophy Dept: Electrical and Computer Engineering Thesis Title: Minimizing Queueing Delays in Computer Networks Abstract The current Internet provides a best-effort packet service using the Internet Protocol. It offers no guarantees on actual packet deliveries and users need not make reservations before transmitting packets through it. This architecture has been tremendously successful in supporting data applications as demonstrated by the remarkable growth of the Internet usage over the last decade. However, as the Internet evolves to become a global communication infrastructure, two key weakness have become increasingly obvious. Firstly, it is unable to provide service differentiation so that the network can utilize resources more efficiently to support the many new real-time applications that have started to proliferate over the Internet. Secondly, there is a lack of flow isolation within aggregated traffic which allows congestion unresponsive flows, such as User Datagram Protocol (UDP) flows, to squeeze out the congestion responsive ones, such as Transmission Control Protocol (TCP) flows. In this thesis, an original service differentiation framework, called the Delay-Rate Differentiated Services, is proposed. This framework is able to efficiently provide delay-based service differentiation and flow isolation within the best-effort traffic aggregates, thus resolving the key deficiencies of the best-effort paradigm. Keywords: Differentiated Services, Quality of Service, Delay Differentiation, Fair Bandwidth Allocation, Control-theoretic Approach . Name: Ngin Hoon Tong Degree: Doctor of Philosophy Dept: Electrical and Computer Engineering Thesis Title: Minimizing Queueing Delays in Computer Networks Abstract The current Internet provides. successful in supporting data applications as demonstrated by the remarkable growth of the Internet usage over the last decade. However, as the Internet evolves to become a global communication infrastructure,. a best-effort packet service using the Internet Protocol. It offers no guarantees on actual packet deliveries and users need not make reservations before transmitting packets through it. This architecture