Cisco Technology, Inc.

Tauseef Hashmi

Thomas James Edsall

Arthur Lin

A router classifies packets assigned to X*Y classes of service into X classes of service supported by the router, each of the X classes of service having Y loss-priority levels. The router maintains a free queue that links available entries of a buffer in which packets are stored. A weighted average depth of the free queue is used to determine whether to retain a given packet. If the weighted average is above a maximum threshold, the packet is retained. If the weighted average is below a minimum threshold, the packet is discarded. If the weighted average is between the two thresholds, a probability of discard that is based on the X*Y classes of service is calculated and compared to a random value to determine whether the packet should be retained.

Router with class of service mapping

A router includes a classifier that classifies packets assigned to 2 classes of service into 2 classes of service that are supported by the router. The classifier then sets the loss priorities of the respective packets to one of m levels. The router uses a modified weighted random early detection scheme that is based on probabilities of discard associated with the 2 classes of service to determine whether to retain or discard particular packets. The router uses a single buffer to store packets directed to all of the various output ports. The available storage locations in the buffer are linked to a free queue and a weighted average depth of the free queue, is used to determined whether or not to retain a given packet. The router compares the weighted average depth of the free queue to maximum and minimum thresholds associated with the particular 2 class of service to which the packet is assigned. If the weighted average is above the maximum threshold, the packet is retained. If the weighted average is below the minimum threshold, the packet is discarded. If the weighted average is between the two thresholds, a probability of discard that is based on the 2 classes of service is calculated and compared to a random value to determine whether or not the packet should be retained. If the probability of discard exceeds the random value, the packet is discarded. The other packets exit various output ports of the router based on weighting factors associated with the 2 classes of service.

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Freemont, CA, United States of America

Tauseef Hashmi