Roughly described, a packet switching fabric contains a separate queue scheduler for each combination of an input module and a fabric output port. The schedulers may also be specific to a single class of service. Each queue scheduler schedules its packets without regard to state of other input queues and without regard to packets destined for other output ports. In an aspect, the fabric manages per-flow bandwidth utilization of output port bandwidth capacity by monitoring the same and asserting backpressure toward the queue scheduler for any thread that is exceeding its bandwidth allocation. In another aspect, a switching fabric uses leaky buckets to apply backpressure in response to overutilization of downstream port capacity by particular subflows. In another aspect, a switching fabric includes a cascaded backpressure scheme.
CROSS-REFERENCES
This application claims the benefit of U.S. Provisional Application No. 60/362,144, filed Mar. 6, 2002, incorporated herein by reference in its entirety.
