Evaluation of the performance of the simulation of a campus network in OPNET

Thumbnail Image



Journal Title

Journal ISSN

Volume Title


University of New Brunswick


Simulation is widely used to test the performance of computer networks under different operating conditions. The aim of this report is to evaluate the accuracy of the network simulation using OPNET. Measuring the data transfer rate of an FTP session on the FCS campus network was used as the case study. Two approaches were used to validate the results of simulation. The first approach compared the simulation results with the calculations based on an analytical model. The second approach was based on the comparison of the results obtained from the simulator with the network measurements. The results show that in the case of a simple scenario (three clients connecting to a server) the simulator's network model was close to the actual network performance (the average transfer rate difference between individual flow data rates of 24.7 Mbps) and the analytical results were almost the same as those of the simulation (difference of 0.1 Mbps). In a more complex scenario (up to thirteen clients), the results from the simulator's network model differed from the measurement of the actual network (average transfer rate difference of 404.7 Mbps) and from the analytical calculations (average transfer rate difference of 326.7 Mbps). Furthermore, this difference was large when measured between the data rates of individual (pairs of) flows, while the difference between the averages of all flows in one time slot between OPNET and Iperf was small.