Fairness Comparisons among Modern TCP Implementations

Over modern long fat networks, enough throughput is not obtained using TCP Reno, which is the classical standard TCP congestion avoidance algorithm. For this reason, many high performance TCPs have been proposed, such as Compound TCP (CTCP) and CUBIC TCP. Then, these proposals caused a new issue, which is fairness among these modern TCPs. For this issue, several fairness evaluations and some proposals for improving fairness have been published. However, most evaluations are executed using network simulator, so fairness in actual network elements and actual TCP implementations has not been discussed enough yet. In this paper, we present fairness evaluation among modern TCPs with actual network elements and actual TCP implementations. Our evaluations demonstrated that fairness among modern TCPs is very poor, especially in case of using CUBIC. Furthermore, we evaluated existing fairness improving method. The results show that the methods can improve fairness.