| This research examines the performance of fully connected switches, crossbars, with respect to the Message Length Distribution (MLD) of the traffic passing through the switch. The switches studied are input-queued with no blocking due to output limitations and are studied in the saturated condition with traffic having a uniform destination distribution. By examining previous literature and investigating theoretical models, this research establishes that theoretical state models are far too difficult to derive and, if they exist, would be virtually impossible to use for numerical studies. Thus, the research turns to simulation. Previous studies and newer models developed in this research were are to validate the simulator. The simulator provides the ability to test many switch scenarios. Simulations lead to two MLD parameters (Average Message Length (AML) and variance) that determine the influence of MLD on throughput. The research provides six major contributions. (1) New theoretical models for 2 x 2 and 4 x 4 switches experiencing bimodal MLDs are developed. (2) A robust simulator that models the input-queued crossbar switch with a wide variety of MLDs are developed and validated. (3) Two conjectures, the Synchronization Conjecture and the MLD Independence Conjecture, relating to switches using wormhole routing are formed. (4) Switch throughput models with respect to MLD are developed for wormhole routed and individual routed switches. (5) Methods for using the models to compare total throughput, data throughput, and service time using the models are developed and applied to a parallel web saver. (6) The simulator is modified to model the Tandem ServerNet II switch architecture and used to find that the previous models apply to the ServerNet II switch as well. |
