Work-conserving-based packet scheduling algorithm for CICQ switches

Although packet scheduling for combined input-crosspoint-queued (CICQ) switches has been extensively investigated, the performance in terms of throughput and average delay of packets is not satisfied, especially compared to the results obtained by employing output queued architecture. The key reason is that output queneing(OQ) switch can operate in work-conserving state. Different from the popular approaches appeared in the literatures, our work focuses on scheduling packet so that the switch works approximately in work-conserving state to the largest extent. First, the sufficient and necessary conditions for the switch with CICQ architecture to work in work-conserving state are investigated and proved. Then, a new CICQ input scheduling algorithm called crossbuffer queue balance (CQB) is put forward, which is combined with the classical longest queue first (LQF) scheduling used for output arbiter to obtain CQB-LQF algorithm. Simulation results show that the performance in terms of throughput and average packet delay obtained by CQB-LQF is much better than the classical and popular algorithms.