Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Random Early Detection (RED) Floyd/Jacobson (1993,ToN) 。 Design goals - Congestion avoidance,as opposed to congestion reaction. Control average delay through a router.Achieved by controlling queue length. Fairness.For instance,don't always select newly arriving packets to drop. Avoid network-wide collapse. 。 Metric is moving average of queue lengths small bursts pass through unharmed only affects sustained overloads Packet drop probability is a function of mean queue length prevents severe reaction to mild overload Can mark packets instead of dropping them allows sources to detect network state without losses 。 No bias against bursty sources Controls queue length regardless of endpoint cooperation 2616009:Network Traffic Engineering 5:Buffer Management Page.142616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.14 Random Early Detection (RED) • Floyd/Jacobson (1993, ToN) • Design goals - Congestion avoidance, as opposed to congestion reaction. - Control average delay through a router. Achieved by controlling queue length. - Fairness. For instance, don’t always select newly arriving packets to drop. - Avoid network- wide collapse. • Metric is moving average of queue lengths - small bursts pass through unharmed - only affects sustained overloads • Packet drop probability is a function of mean queue length - prevents severe reaction to mild overload • Can mark packets instead of dropping them - allows sources to detect network state without losses • No bias against bursty sources • Controls queue length regardless of endpoint cooperation