Analysis and improvement of fairness between long-lived and short-lived TCP connections

摘要

Short-lived TCP connections, which send small data, suffer from significant low throughput compared with long-lived TCP connections, which transmit large documents. It is because of an inherent nature of the ACK-based window flow control of TCP. In this paper, we focus on the unfairness problem of TCP connections transmitting differently sized documents. To improve the fairness, it is necessary to treat packets from short-lived TCP connections preferentially over those from long-lived TCP connections. For realizing it, we first introduce a new analysis approach to estimate the throughput of TCP connections in the case where the packet loss probability of each transmitted packet from the same connection is different. Our analysis can give a better estimation of the TCP throughput than the existing analysises. Using the analysis results, we propose a new algorithm to improve the fairness, and investigate its effectiveness through simulation experiments. We show that our proposed algorithm can improve the fairness without degradation of the network utilization.