Sansa-Otim, JulianneRai, Idris A.van der Hulst, J. M.2022-05-022022-05-022010Sansa-Otim, J., Rai, I. A., & van der Hulst, J. M. (2010, April). F-TCP: a Delay-based Protocol with Fair Co-existence. In 2010 Ninth International Conference on Networks (pp. 34-41). IEEE. DOI 10.1109/ICN.2010.1410.1109/ICN.2010.14https://nru.uncst.go.ug/handle/123456789/3154Various studies have shown that regular TCP is inefficient in high-speed networks. This paper proposes F-TCP, a delay-based TCP variant, which is able to operate efficiently in high-speed networks. The slowstart phase of F-TCP continues until a threshold determined from probing the available bandwidth. When competing with loss-based flows F-TCP reduces it’s window to a value derived from the available bandwidth. More specifically, an adaptive bandwidth share estimation with a delay-sensitive instability measure is employed to guide window backoff when congestion is detected by F-TCP. Using ns-2 simulations we show that F-TCP has good throughput efficiency, intra-protocol fairness and TCP friendliness properties. Our results also illustrate fair coexistence between a delay-based protocol (F-TCP) and a loss-based protocol (regular TCP) thus F-TCP maintains it’s fair share of the link. In addition we show that F-TCP avoids self-induced packet losses by using delay as the congestion signal hence zero packet loss is experienced in all the simulations where all the flows are F-TCP. In simulations with regular TCP, packet losses are inevitable since it is loss-based. We therefore conclude that when treated carefully, delay (or RTT) can indeed be a useful congestion signal indicator. Bandwidth estimation is a good indication of available bandwidth for delay-based flows if made aware of the early congestion back off experienced by these flows.enHigh-speed networksTCP congestion controlDelay-based protocolBandwidth estimationArticle