Accurate approximate analysis of cell-based switch architectures

In this paper, we present an accurate new approximate analytical technique for the performance analysis of cell-based switch architectures, and validate it by means of numerical results derived for a number of switch configurations that allow a comparison of the approximate analytical performance predictions against either analytical results or simulation point estimates and confidence intervals. The new approximate analytical technique is based on the separate study of two parts of the switch: the internal switching fabric, and the buffers associated with the output line interfaces. The study of the first part, subjected to the switch input traffic, allows the probabilistic characterization of the cell flows at the ingress of the output buffers. This in turn permits the study of the second part, separately considering each output buffer subjected to an input cell flow generated by a synthetic source that tries to mimic the characteristics of the true cell flow entering the output buffer under investigation. In addition to the numerical results that allow the validation of the approximate analysis technique, we also present some example analytical results for large switch configurations, for which an exact analysis is not feasible, and simulation is extremely costly, as well as some results that permit the assessment of the robustness of the approach with respect to errors in the characterization of cell flows at the output buffer ingresses.