PIQI-RCP: Design and Analysis of Rate-Based Explicit Congestion Control

Recent research has created a significant interest [18], [19] in the design and development of a new global-scale communication network that can overcome the limitations of the current Internet. Among the many directions for improving networking technology, recent pursuit to design better flow control has led to the emergence of explicit congestion control methods that solicit active feedback from intermediate routers [5], [11], [22], [25], [26]. As a step towards understanding these methods, we analyze stability and transient performance of Rate Control Protocol (RCP) [5], which is a recent method that aims to emulate processor sharing and achieve quick flow completion. However, we find that RCP can become unstable in certain topologies and may exhibit very high buffering requirements at routers. To address these limitations, we propose a new controller called Proportional Integral Queue Independent RCP (PIQI-RCP), prove its stability under heterogeneous delay, and use ns2 simulations, as well as Linux experiments, to show that the new method has significantly better transient dynamics (i.e., much smaller link-capacity overshoot) and better stability properties in single-and multi-bottleneck scenarios.