The effect of router buffer size on R-bias in high-speed variants of TCP
Aun Haider, Akihiro Nakao · International Symposium on Performance Evaluation of Computer and Telecommunication Systems · 2009
This paper investigates the effect of changes in router buffer size on throughput and fairness characteristics of high-speed variants of TCP. Whereas for fairness, round-triptime (R)-bias has been focussed. A generalized model for R-bias has been developed, while using Droptail and Random Early Detection (RED) routers, [1], at a bottleneck link. An existing optimal buffer sizing scheme has been also generalized to include the case of high-speed variants of TCP. In addition, through NS-2 based simulations, we have found that R-bias for most of the high-speed TCPs, under Droptail, increases as buffer size grows; whereas Hamilton TCP [2] and Compound TCP [3] have shown the best performance under smaller buffer size. On the other hand, while using a RED router, R-bias for all the high-speed TCPs has been shown to be much less than Droptail, though with a slight drop in total throughput of all TCP connections. An interesting observation is that R-bias for HighSpeed TCP [4] and Scalable TCP [5], initially increases as buffer size grows, which later on start decreasing and reach almost to negligible values for the larger size of buffers for RED router; thus providing a quite good intra-protocol fairness. Another contribution of this paper is that R-bias in high-speed TCPs can be effectively controlled by employing delay-loss based congestion avoidance, [3], as well as by active queue management schemes, such as RED.