RRGS-round-robin greedy scheduling for input/output terabit switches

摘要

A novel protocol for scheduling of packets in high-speed cell based switches is provided. The switch is assumed to use a logical cross-bar fabric with input buffers. The scheduler may be used in optical as well as electronic switches with terabit capacity. The proposed round-robin greedy scheduling (RRGS) achieves optimal scheduling at terabit throughput, using a pipeline technique. The pipeline approach avoids the need for internal speedup of the switching fabric to achieve high utilization. A method for determining a time slot in a NN crossbar switch for a round robin greedy scheduling protocol, comprising N logical queues corresponding to N output ports, the input for the protocol being a state of all the input-output queues, output of the protocol being a schedule, the method comprising: choosing input corresponding to i(constant-k1)mod N, stopping if there are no more inputs, otherwise choosing the next input in a round robin fashion determined by i(i1)mod N; choosing an output j such that a pair (i,j) to a set C(i,j) there is at least one packet from I to j, if the pair (i,j) exists; removing i from a set of inputs and repeating the steps if the pair (i,j) does not exist; removing i from the set of inputs and j from a set of outputs; and adding the pair (i,j) to the schedule and repeating the steps.