Towards experimental evaluation of explicit congestion control

Abstract

Innovative efforts to provide a clean-slate design of congestion control for future high-speed heterogeneous networks have recently led to the development of explicit congestion control. These methods rely on multi-byte router feedback and aim to contribute to the design of a more scalable Internet of tomorrow. However, experimental evaluation and deployment experience with these approaches is still limited to either low bandwidth networks or simple topologies. In addition, all existing implementations are exclusively applicable to either rate- or window-based protocols and are unable to study performance of different protocols on a common platform. This paper aims to fill this void by designing a unified Linux implementation framework for both rate- and window-based methods that does not incur any interference with the system's network stack or applications. Using this implementation, we implement and reveal several key properties of four recent explicit congestion control protocols XCP, JetMax, RCP, and PIQI-RCP using Emulab's gigabit testbed with a ariety of simple yet representative network topologies. Our experiments not only confirm the known behavior of these methods, but also demonstrate their previously undocumented properties (e.g., RCP's transient overshoot under abrupt traffic load changes and JetMax's low utilization in the presence mice flows).