Dell C1048P Port Extender Networking Command-Line Reference Guide for the C900 - Page 1541

Command History Version 9.9(0.0) 9.2.1.0 9.3.0.0 Description Introduced on the C9010. Introduced on the Z9500 switch. Introduced on the S6000 and Z9000 platforms Usage Information If the average queue size is more than the maximum threshold of WRED, the packet is dropped. If the average queue size is between the minimum and maximum threshold values, the decision to drop or queue the packet is taken based on the packet drop probability. The probability that a packet is dropped depends on the minimum threshold, maximum threshold, and mark probability denominator. Example Dell(conf-qos-policy-out)# wred weight 5 wred ecn To indicate network congestion without dropping packets, use explicit congestion notification (ECN). C9000 Series Syntax wred ecn To stop marking packets, use the no wred ecn command. Defaults none Command Modes QOS-POLICY-OUT mode Command History This guide is platform-specific. For command information about other platforms, refer to the relevant Dell Networking OS Command Line Reference Guide. The following is a list of the Dell Networking OS version history for this command. Version 9.9(0.0) 9.2(1.0) 8.3.19.0 8.3.11.1 8.3.7.0 Description Introduced on the C9010. Introduced on the Z9500. Introduced on the S4820t. Introduced on the Z9000. Introduced on the S4810. Usage Information When you enable wred ecn, and the number of packets in the queue is below the minimum threshold, packets are transmitted per the usual WRED treatment. When you enable wred ecn, and the number of packets in the queue is between the minimum threshold and the maximum threshold, one of the following scenarios can occur: • If the transmission endpoints are ECN-capable and traffic is congested, and the WRED algorithm determines that the packet should have been dropped based on the drop probability, the packet is transmitted and marked so the routers know the system is congested and can slow transmission rates. Quality of Service (QoS) 1541