Alcatel Lucent

Bin Du

Adrian Grah

Larry Friesen

Mark Thibodeau

Robert John Johnson

At telecommunications switches and routers, RED (random early packet discard) uses the queue depth to determine whether to keep or discard each packet as it arrives at a queue. This is done by determining a discard probability (P), which is dependent on the average depth of the queue, and comparing the discard probability to a random number. One way of performing the invention uses the summed discard probabilities, instead of counting the number of packets (count) and multiplying that by the current discard probability, as in the prior art. The resulting sum is compared to the random number for discard operation. The disclosure further describes a more accurate way of calculating average depth of a queue, especially when the queue encounters periods of idleness.

Random early packet discard (RED)

Systems and methods of reducing service jitter in WFQ scheduling schemes used in packet traffic management are described. Service jitter is the variance in time between when a queue should have been selected for servicing and when it was actually serviced. The service jitter is generally not a problem in lower speed applications but in a high speed implementation such as a OC192 device latency can lead to downstream service contract violations. According to the invention jitter is controlled by applying a dampening factor to a difference amount that is used by the WFQ process to adjust its timing of queue selection. The difference amount is queue-specific and is a running difference between calculated and actual queue servicing times.

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Bin Du