Performance evaluation of the rate-based flow control mechanism for ABR service

In this paper we investigate the performances of the EFCI-based (Explicit F orward Congestion Indication) and ER-based (Explicit Rate) algorithms for t he rate-based flow control of the ABR (Available Bit Rate) traffic in an AT M network. We consider the case of two switches in tandem. We present sever al definitions of a bottleneck, and provide conditions that determine wheth er the first, the second or both queues are bottleneck. We show that it is not necessarily the queue with the slowest transmission rate in which conge stion actually occurs. We derive analytic formulas for the maximum queue le ngth. We compare our results to those obtained by approximating a network b y a simpler one, containing only the bottleneck switch. We show that the ma ximum queue lengths under the approximating approach may largely underestim ate the ones obtained in the real network.