Longest queue first in round-robin matching for input-queued switches

In this paper, we developed a new virtual output queue (VOQ) scheduling algorithm called “longest queue first in round-robin matching” (LQFRRM) for input-queued switches. Based on the well-known iSLIP algorithm, we proposed a new update policy for the output round robin pointers. That is, when a grant is not accepted, all the output round robin pointers are updated to the longest queue. The rationale is that a grant not accepted will leave an output port idle and that means a less than optimal solution. Therefore, a better alternative is to give priority to the longest queue, especially under non-uniform traffic. The simulation results showed that LQFRRM was better than iSLIP in non-uniform traffic and was comparable to iSLIP in uniform traffic.