Scheduling algorithms for input-queued switches with virtual output queueing

A set of packet scheduling algorithms are proposed for improving the performance of an iterative longest port first (iLPF) algorithm for virtual output queueing (VOQ) switches. In our proposed algorithms, scheduling priority is given according to different criteria that include input port occupancy, output port occupancy and critical port in VOQ. One of the proposed algorithms, called longest input port first with throughput maximization (LIPF with TM), gives significant performance improvement in mean packet delay and throughput when compared with iLPF. We found that for a 16×16 switch with input load p=0.85, the mean packet delay is 7.08 slots for iLPF and 3.21 slots for LIPF with TM. This represents a 55% cut in mean packet delay