Two Problems of TCP AIMD Congestion Control

AIMD (additive increase and multiplicative decrease) algorithm has been used in many congestion control protocols, including TCP in the Internet. In this paper, we compare AIMD and MAIMD (multiplicative additive increase and multiplicative decrease). Our evaluation shows that the convergence speeds to fair states of AIMD and MAIMD are close to each other. However, MAIMD has some advantages. For example, its speed to use available network bandwidth can be much faster than AIMD. We have also investigated AIMD behaviors under a more realistic asynchronous system model. Under this model, AIMD system can have more than one attractors, which can be another contributor to the fairness problem of TCP.