Westwood+ TCP is a sender-side only modification of the classic Tahoe/Reno TCP that has been recently proposed to improve fairness and efficiency of TCP. The key idea ofWestwood+ TCP is to perform an end-to-end estimate of the bandwidth available for a TCP connection by properly counting and filtering the stream ofACKpackets. This estimate is used to adaptively decrease the congestion window and slow-start threshold after a congestion episode. In this way,Westwood+ TCP substitutes the classic multiplicative decrease paradigm with the adaptive decrease paradigm. In this paper we report experimental results that have been obtained running Linux 2.2.20 implementations of Westwood+, Westwood and Reno TCP to ftp data over an emulated WAN and over Internet connections spanning continental and intercontinental distances. In particular, collected measurements show that the bandwidth estimation algorithm employed byWestwood+ nicely tracks the available bandwidth, whereas the TCP Westwood bandwidth estimation algorithm greatly overestimates the available bandwidth because of ACK compression. Live Internet measurements also show that Westwood+ TCP improves the goodput w.r.t. TCP Reno. Finally, computer simulations using ns-2 have been developed to testWestwood,Westwood+ and Reno in controlled scenarios. These simulations show that Westwood+ improves fairness and goodput w.r.t. Reno.
|Autori interni:||GRIECO, Luigi Alfredo|
|Titolo:||Performance evaluation of Westwood+ TCP congestion control|
|Data di pubblicazione:||2004|
|Digital Object Identifier (DOI):||10.1016/S0166-5316(03)00098-1|
|Appare nelle tipologie:||1.1 Articolo in rivista|