Abstract: 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.

Abstract: A router includes a classifier that classifies packets assigned to 2n−m classes of service into 2n 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 2n+m 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 2n+m class of service to which the packet is assigned. If the weighted average is above the maximum threshold, the packet is retained.