Quantifying the effects of recent protocol improvements to standards-track TCP

Abstract

We assess the state-of-the-art in Internet congestion control and error recovery through a controlled study that considers the integration of standards-track TCP error recovery and both TCP and router-based congestion control. The goal is to examine and quantify the benefits of deploying standards-track technologies for Internet traffic as a function of the level of offered network load. We limit our study to the dominant and most stressful class of Internet traffic: bursty HTTP flows. Contrary to expectations and published prior work, we find that for HTTP flows (1) there is no clear benefit in using TCP SACK over TCP Reno, (2) unless congestion is a serious concern (i.e., unless average link utilization is above approximately 80%), there is little benefit to using Adaptive RED queue management, (3) above 80% link utilization there is potential benefit to using Adaptive RED with ECN marking, however, complex performance trade-offs exist and results are sensitive to parameter settings.