Desynchronized Two-Dimensional Round-Robin Scheduler for Input Buffered Switches

We propose a new arbitration algorithm, called the desynchronized two-dimensional round-robin (D2DRR), for input queued packet switches in which each input port maintains a separate logical queue for each output. D2DRR is an enhanced version of 2DRR, and thus improves fairness over 2DRR without a starvation problem. Iterative maximal matching schemes including iSLIP yield better throughput with more iterations. However, since many iterations require much time for arbitration, it is not desirable for high speed switching. Thus, D2DRR attempts to resolve contentions with less iterations, while yielding high throughput. The proposed arbitration algorithm is compared in terms of average cell latency with conventional algorithms, especially iSLIP and wrapped wave front arbitration (WWFA).