Patent ID: 7852866
Filing Date: 2010-12-14
Classification: H04L

Abstract:
1. For use in a buffered crossbar switch having a plurality of output ports, a plurality of input ports, each of the plurality of input ports having a virtual output queue corresponding to each of the plurality of output ports, and a switch fabric coupling each of the input ports with each of the output ports, defining crosspoints and including a buffer in the switch fabric at each input port-output port crosspoint, a scheduling method comprising: a) for each input port, selecting either (A) the previously served virtual output queue, or (B) a virtual output queue corresponding to a uniform probability selection output for a time slot, as a function of queue lengths of the previously served virtual output queues of all of the plurality of input ports and queue lengths of the virtual output queue corresponding to the uniform probability selection output, for all of the plurality of input ports; b) if both (1) the selected virtual output queue is non-empty and (2) the corresponding crosspoint buffer is not full, then serving the selected virtual output queue, otherwise serving another, non-empty, virtual output queue with a corresponding non-full crosspoint buffer, using an alternative selection discipline; c) for each output port, selecting either (A) the previously served crosspoint buffer, or (B) a crosspoint buffer corresponding to the uniform probability selection output for the time slot, as a function of queue lengths of the previously served virtual output queues of all of the plurality of input ports and queue lengths of the virtual output queue corresponding to the uniform probability selection output, for all of the plurality of input ports; and d) if the selected crosspoint buffer is non-empty, then serving the selected crosspoint buffer, otherwise serving another, non-empty, crosspoint buffer using an alternative selection discipline.