Performance Evaluation of a Synchronous Bulk Packet Switch Under Real Traffic Conditions

摘要

Real traffic flows are captured in various network environments and their statistical properties are analyzed. Based on real traffic flows, MWM (Multifractal Wavelet Model) and Poisson equivalent synthetic traffic flows are generated. Performance analysis of a SB (Synchronous Bulk) packet switch is joined with different types of traffic. Maximum throughput performance of the SB packet switch for various real traffic flows and appropriate MWM and Poisson equivalent synthetic traffic flows are evaluated by using discrete-event simulations. Different flow persistence, SF (Stretch Factor) and scheduling mechanisms are used in order to asses their influence on SB packet switch performance. Traffic asymmetry, either input or output based, has a major influence on SB packet switch performance. By increasing the level of asymmetry, maximum throughput values decrease considerably, especially if the ROT (Rotation) scheduling mechanism is applied. Traffic asymmetry also decreases the influence of the SF parameter on maximum switch throughput. As a general rule of thumb, SF values of no more then 5 must be used if asymmetrical traffic is switched. It is also advisable that OPF (Oldest Packet First) scheduling mechanism is used in such cases. The influence of burstiness and scaling of traffic flows turns out to be relatively insignificant for the SB packet switch maximum throughput results, if the OPF scheduling mechanism is used. Larger throughput discrepancies are detected, if ROT scheduling is used.