Impact of scheduling algorithms on performances of buffered crossbar switch fabrics

In this paper, the impacts of different scheduling algorithms on buffered crossbar switch (BCS) performances are analyzed. Four BCSs are considered: combined input- and crosspoint-queued (CICQ) switch, output-queued with speed-up N (OQ-N) switch virtual ouput-queued with iterative longest input part first (VOQ) switch and virtual output-queued with longest input port first and with throughput maximization (VOQL) switch. As solutions for input buffers and crosspoint buffers scheduling procedures, longest queue first (LQF), oldest cell first (OCF) and round robin (RR) algorithms are implemented. The simulation results show that different BCSs have very close performances, irrespective which scheduling algorithm is implemented, for both uniform and bursty traffic. Also simulations indicate that CICQ switches an very close to OQ-N. Taking into account cost-effectiveness it is proved that the RR scheduling algorithm has great perspective as an easy solution for CICQ high speed switch implementation.