TCP Westwood Experiments over Large Bandwidth-Delay Product Networks

Abstract — The Internet is evolving, and this evolution occurs at the physical, network and transport layers, promoted mainly by the advent of photonics networks. However, the nature of TCP Reno, the widely used transport layer protocol, leads to several drawbacks in photonics backbones with large bandwidth delay product (BDP) characteristic. TCP Reno suffers more from random losses whenever the BDP increases to higher values. Furthermore, the congestion avoidance mechanism takes a long time to converge to the appropriate full bandwidth utilization level. In order to address these problems, some new protocols have been proposed like HSTCP, FAST and also TCP Westwood. In this paper, we will present some measurements and evaluation of TCP Westwood in the context of two in-production large BDP links; UCLA to University of Alabama and UCLA to CalTech. We will see that on one hand, TCP Westwood works as well as the others in many criteria like stability and fairness, and on the other hand it achieves better utilization of the link whenever there are high amount of random losses. I