Patent ID: 6982956

Claim:
A method for controlling congestion at an output from a node in a data communications network wherein data is transmitted in packets, each packet having a discardability characteristic, said method comprising the steps of: establishing a set of available, alternative discard strategies for packets having different discardability characteristics; maintaining a profile of packets recently received at the output, the profile reflecting the discardability characteristics of said packets, wherein the step of maintaining a profile further comprises the steps of maintaining a count of the number of packets actually stored in an output buffer at the output, and maintaining counts of the number of said packets which would have been stored in the output buffer if different discard strategies in a set of available discard strategies had been in effect during the receipt of the packets actually stored in the output buffer, monitoring the output to detect the onset of congestion; upon detection of congestion, using the profile to select an initial discard strategy; initiating the selected initial discard strategy; continuing to monitor the degree of congestion at the output; and selecting and initiating one or more subsequent discard strategies as the degree of congestion changes, wherein each successively initiated discard strategy is intended to result in the discard of fewer packets than the previously initiated discard strategy.