A performance-enhanced parallel scheduling algorithm for MIQ switches providing a QoS guarantee

A novel parallel scheduling algorithm, namely a parallel solitary-request-first (PSRF) algorithm, is proposed to improve the performance of the multiple input-queued (MIQ) switch. The proposed algorithm is basically based on the three-phase scheme consisting of request, grant, and accept phases. The essential idea of PSRF is to select the solitary requests with preference. By doing so, PSRF enhances the throughput of the MIQ switch whose input has less number of queues than the switch size. Simulation results for the i.i.d. Bernoulli traffic demonstrate that 2 or 4 queues are appropriate in terms of simplicity, efficiency, and operation speed. Further, to provide a QoS guarantee in the MIQ switch, we developed an enhanced PSRF scheduler which is a kind of the hierarchical or hybrid scheduling algorithm. Hierarchical scheduling is a mixture of a static scheduling with a dynamic scheduling. That is, after finding out an optimal set of input-output matchings, the scheduler chooses one VC connection or a cell in the corresponding virtual queue so as to provide a high throughput as well as the QoS guarantee.