A Simulation Study of Delay and Delay Variation in ATM Networks, Part 1: CBR Traffic

Through comprehensive simulation studies, we have evaluated the ATM layer end-to-end performance of a Constant Bit Rate (CBR) MPEG2 connection. For most practical cases that we have considered, a Cell Delay Variation (CDV) value of 160sec is obtained (using 155 Mbps OC-3 rate), well below the 1 msec worst case stated in prior studies 1]]2]. The results also indicate that the Uniform distribution proposed in the ATM Forum provides a pessimistic model for the cell delay variation. We demonstrate that a Gamma distribution adequately models the cell delay and delay variation (CDV). We also study the eeect of various network/source parameters (such as the background load, the number of background sources, the number of hops, and the link-speed) on the variances of CDV and the end-to-end delay of the reference connection. Finally, we examine the variation in the cell delay correlation of a reference connection with the above parameters. We show that the correlation is a decreasing non-periodic/periodic function if the reference CBR is multiplexed with the same/other classes of CBR connections .