A Control Theoretical Approach to a Window-based Flow Control Mechanism with Explicit Congestion Notification

A window-based flow control mechanism is a sort of feedback-based congestion control mechanisms, and has been widely used in current TCP/IP networks. Recently proposed TCP Vegas is another version of the TCP mechanism and has potential to achieve much better performance than current TCP Tahoe and Reno. However, it has not been fully investigated how to determine control parameters of TCP Vegas. In this paper, we focus on a window-based flow control mechanism based on a congestion avoidance mechanism of TCP Vegas. We first present a control theoretic analysis for its stability. We then discuss several drawbacks of the window-based flow control mechanism, being inherited from TCP Vegas, through simulation experiments. We finally investigate how these drawbacks is solved by incorporating the ECN (Explicit Congestion Notification) mechanism into the window-based flow control mechanism.