Modified Controlling Queue Delay for TCP fairness improvement

Abstract

For overcoming performance decline caused by current long fat networks, many high performance TCPs have been proposed, such as Compound TCP and CUBIC TCP. These proposals have raised a new issue, which is fairness among these modern TCPs. For this issue, several fairness evaluations and some proposals for improving fairness were published. In our past work, we focused on Controlling Queue Delay (CoDel) and proposed a method for improving performance fairness of modern TCPs by modifying CoDel. However, this existing method assumed that the most bandwidth-consuming connection was given for network elements. In this paper, we discuss a method for improving TCP fairness without such an assumption. First, we present fairness evaluation among modern TCPs with and without CoDel, and then demonstrate that fairness among these TCPs is very poor. Second, we propose a method for improving performance fairness. The method monitors network packets and guesses the most bandwidth-consuming connection from the monitored packets. Then, it drops packets in the most bandwidth-consuming connections more aggressively in the network element. Third, we evaluate our proposed method and show that our method can improve performance fairness.