An optimization approach to ABR control

Available bit rate (ABR) sources react to network feedback by adjusting their transmission rates. Most schemes fall into one of two types depending on what is fed back and where the control decision is made. Explicit congestion notification schemes allow sources to make control decisions but only with incomplete information on congestion. Explicit rate schemes use more accurate congestion information but make the control decision inside the network without regard to the different desires of various sources. We propose an optimization approach that attempts to combine the advantage of both types of scheme. The objective is to maximize the total utility of all sources over their transmission rates. The dual problem suggests treating network links and ABR sources as processors in a distributed computation system to solve the dual problem using the gradient projection algorithm. In this system ABR sources select transmission rates that maximize their own benefits and network links adjust bandwidth prices to coordinate the sources' decisions. We show how to implement such a system using features defined in the ABR standard. We provide an asynchronous distributed algorithm for links and sources and illustrate their behavior with preliminary simulation results.