Towards Experimental Evaluation of Explicit Congestion Control

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 (N. Dukkipati, et al., Jun. 2005), (S. Jain, et al., June 2007), (D. Katabi, et al., Aug. 2002), (Y. Zhang, et al., April 2006) 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, especially in high- capacity networks and multi-link settings, is still missing from the literature. This paper aims to fill this void and investigate the behavior of these methods in single and multi-link topologies involving real systems and gigabit networks. We implement four recent protocols XCP (D. Katabi, et al., Aug. 2002), JetMax (Y. Zhang, et al., April 2006), RCP (N. Dukkipati, et al., Jun. 2005) and PIQI-RCP (S. Jain, et al., June 2007) in the existing Linux TCP/IP stack (Linux) in a manner that is transparent to applications and conduct experiments in Emulab using a variety of network configurations. Our experiments not only confirm the known behavior of these methods, but also demonstrate their previously undocumented properties.