Multiple Priorities in a Virtual-Priority-Output Queueing Buffered Crossbar

In order to support multiple priority levels, separate queues per priority are required at each crosspoint, much more memories and many schedulers are needed in a buffered crossbar, which are costly and inefficient. According to effectively support multiple priorities, this paper presents a virtual-priority-output queueing (VPOQ) architecture, based on a buffered crossbar, and proposes a novel scheduling mechanism by definition of dual priority. At each input port of a buffered crossbar, a parallel scheduling on priority queues and a round robin scheduling algorithm, both based on dual priority, are put forward. Schedulers at crosspoints function in a round robin manner. Compared with current scheduling algorithms supporting multiple priorities in a buffered crossbar, our project need not per priority queueing at per crosspoint, can not only avoid complicated scheduling in the fabric but also provide flow isolation and protection, and the implementation is relatively simple. Simulation results are presented to evaluate the delay property of our scheme, indicating that our scheme can match a buffered crossbar with per priority queueing at per crosspoint