FDDI performance analysis: Delay approximations

The authors review and propose approximations for the station waiting times in the medium access control (MAC) protocol of the fiber distributed data interface (FDDI). Simulation is used to investigate the accuracy of these approximations for different sets of system parameters. While the throughput performance of FDDI has been successfully analyzed, few useful results have been developed for delay performance. It was found that the timed-token service discipline of FDDI behaved like the exhaustive service discipline up until relatively high utilizations. That is, the timed-token service discipline only significantly affected the mean waiting times for utilizations that were within 5-20% (depending upon the case) of the maximum utilization ρmax. For a given ρ, the larger the average number M(ρ) of frames served during a station service time interval, the more exhaustive the behavior of the timed-token service discipline.