A performance prediction model for FECN rate-based flow control in ATM networks: a case study

Forward explicit congestion notification (FECN) plays an important role in rate-based flow control for asynchronous transfer mode (ATM) networks. This paper presents a case study in predicting and evaluating the performance of the FECN flow control. Two network models are under investigation; the first model assumes that a target ATM network has no traffic congestion, while the second model assumes that the network has exhibited heavy congestion. For the light-loaded network, we first estimate the number of cells issued by the source during each time interval and then calculate the required number of resource management (RM) cells in the same time interval. A general analytical form to predict allowable cell rate (ACR) at the source can be finally derived. For the heavy-loaded network, RM cells may be delayed and data cells may be discarded due to severe network congestion. Hence, to derive a general form of ACR, we need to estimate the round-trip time (RTT) of RM cells based on the queuing length of the traversed ATM switches. For the purpose of validation, we perform simulation through OPNET. The performance parameters of our interest include the ACR, the RTT of RM cells, the throughput and the cell loss ratio. We have shown that the differences between the analytical and the simulation results are quite small not only in the ACR adjusting rate, but also in the prediction of the system throughput, the CLR, and the RTT of RM cells. (C) 2002 Elsevier Science B.V. All rights reserved.