Stability Analysis of a Window-based Flow Control Mechanism for TCP Connections with Different Propagation Delays

A feedback-based congestion control mechanism is essential to realize an efficient best-effort service in highspeed networks. A window-based flow control mechanism called TCP (Transmission Control Protocol), a sort of feedbackbased congestion control mechanism, has been widely used in the current Internet. Recently, TCP Vegas has been proposed, which is another version of TCP mechanism, and achieves much better performance than currently used TCP Reno. In this paper, we focus on a window-based flow control mechanism based on the congestion avoidance mechanism of TCP Vegas, and analyze its stability using a control theoretic approach. The main objective of this paper is to analyze the dynamics of the window-based flow control mechanism when TCP connections have different propagation delays. We analytically show that the network always becomes stable if the control parameter of each connection, which determines the amount of window size increase/decrease per round-trip time, is set to be less than the ratio of its propagation delay to the shortest one among connections. 英文 key words TCP/IP Network, Window-Based Flow Control Mechanism, TCP Vegas, Control Theory, Stability Analysis