TCP Startup Performance in Large Bandwidth Delay Networks
Ren Wang, Giovanni Pau, K. Yamada, M.Y. Sanadidi, Mário Gerla · Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna) · 2004
.4brtroct- Nest generation nehvorlis with large bandwidth and long drlay pose a major challenge to TCP performance, especially during the startup period. In this paper we evaluate the performance of TCP RenaiNcwrcno. Vegns and Hoe's modification in large bandwidth delay nrhvork. We propose n modified Slow-start mechanism, rnllcd Adaptive Start (Astart), to improve the startup performance in such networks. When a connection initially begins or re-starts after a coarse timrout,- Astart ndaptivcly and repentedly resets the Slow-start Threshold (suthreslr) based on an cligihlr sending I'iitr estimation mrchanisrn proposrd in TCP Westwond. By iidapting to network conditions during the startup phase. it wndw is able to grow the congestion window (ocnh fast without incurring risk of huNw owrflow and multiple Iossrs. Simulation rxpcrirncnts show that Astart can significantly improve the link utiliiation under various bandwidth, buNrr sur;~nd round-trip propagation timrs. The mrthud avoids both under-utiliriition dur to prrmature Slowstart termination, as wcll ils multiple I~XII~S due to initinlly setting srrlire.sli too high, or. increaing nmd tin) fiat. Experiments also show that Astart uchiews good fttirnrss rind fricndlincss toward TCP NewReno. Lab measuremrnts using a FrreBSD Astart implementation are also reported in this paper, providing futrhcr evidence of the gains nchirvahlr via Astart. Kqw-orr%r-congesrionn control;.sIow-.start; rate estimution. large bundwidth ddq nehvorks I.