Reference Guide

Quality of Service (QoS) | 979
Related
Commands
wred-ecn
z
Use Explicit Congestion Notification (ECN) to indicate network congestion, rather than dropping
packets.
Syntax
wred-ecn
Use the no wred-ecn command to stop marking packets.
Defaults
No default behavior or values
Command Modes
CONFIGURATION (conf-qos-policy-out)
Command
History
Usage
Information
When wred-ecn is enabled, and the number of packets in the queue is below the minimum threshold,
packets are transmitted per the usual WRED treatment.
When wred-ecn is enabled, and the number of packets in the queue is between the minimum threshold
and the maximum threshold, one of the following three 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.
• If neither endpoint is ECN capable, the packet may be dropped based on the WRED drop
probability. This is the identical treatment that a packet receives when WRED is enabled without
ECN configured on the router.
• If the network is experiencing congestion, the packet is transmitted. No further marking is
required.
When wred-ecn is enabled, and the number of packets in the queue is above the maximum threshold,
packets are dropped based on the drop probability. This is the identical treatment a packet receives
when WRED is enabled without ECN configured on the router.
Related
Commands
wred-profile Create a WRED profile and name that profile
trust Define the dynamic classification to trust DSCP
Version 8.3.11.0 Introduced on Z9000
Version 8.3.8.0 Introduced on S4810
wred-profile Create a WRED profile and name that profile