IMPROVING TCP PERFORMANCE USING -CONTROLLED-LOAD SERVICE

Abstract

Flow and congestion control mechanisms in TCP have been designed with the premise that network capacity should be shared equally among competing connections. With the evolution of the Internet from a classless best-effort network to an integrated services network with different classes of service, the premise of equal fair sharing is no longer true. In an integrated services Internet, network bandwidth should be shared in accordance with the reservation made for each session. In this thesis, we , consider a specific class of service, namely controlled-load, which is currently under consideration for deployment in the Internet. To realize this service, we consider minor extensions to the packet queueing and discard mechanisms used in present day routers and TCP's congestion control mechanisms. These mechanisms enable the network to guarantee minimal levels of throughput to different sessions while sharing the residual network capacity in a cooperative manner. Using detailed simulation experiments, we show that with these enhancements in place, TCP is indeed able to provide the desired end-to-end behavior. We also. propose a new algorithm, which recovers multiple packet losses by enabling slow start phase earlier without waiting for long retransmission timeout. This assures controlled-load connections to obtain fair share of excess bandwidth. Software is written in C++, and works under LINUX environment..