Transitional behaviors of general AIMD rate control

Internet applications use rate control algorithms, such as the additive-increase/multiplicative-decrease (AIMD) mechanism of TCP, to adjust transmission rates dynamically. Previous analytical work of rate control algorithms mainly focuses on steady state behaviors, for instance, the steady state throughput. The goal of this paper is to analyze the General AIMD (GAIMD) rate control during transition periods, when traffic flows increase or decrease sending rates in response to changes in network conditions. We present mathematic characterizations of GAIMD flows in transition periods, verify our analytic results by simulation, and investigate the change responsiveness of GAIMD flows using our model. The results of this study show that our model is accurate unless under extremely adverse conditions. Moreover, such adverse conditions exist only for very short periods of time, and thus the errors of the proposed model are likely insignificant. Our results also reveal that previous estimation methods of change responsiveness consistently underestimate the lengths of transition periods. This research advances the understanding of how Internet traffic reacts to changes in network conditions. Such knowledge in turn are expected to help make informed design decisions of rate control algorithms.