STX Scheme for Reducing Latency with Centralized Matching Algorithms

This research work is motivated by the need to achieve low latency in an input-queued centrally-scheduled cell switch for high-performance computing applications; specifically, the aim is to reduce the latency incurred between a request and response arrival of the corresponding grant. The minimum latency in switches with centralized scheduling comprises two components, namely, the control-path latency and the data-path latency, which in a practical high-capacity, distributed switch implementation can be far greater than the cell duration. We introduce a speculative transmission scheme to significantly reduce the average control-path latency by allowing cells to proceed without waiting for a grant, under certain conditions. It operates in conjunction with any centralized matching algorithm to achieve a high maximum utilization. Using this model, performance measures such as the mean delay and the rate of successful speculative transmissions are derived.