Wred-Ecn - Dell Force10 S4810P Reference Manual

Command Modes CONFIGURATION (conf-qos-policy-out)
Command History
Version 8.3.11.1
Version 8.3.7.0
Version 8.2.1.0
pre-Version
6.1.1.1
Usage Use this command to assign drop precedence to green or yellow traffic. If there is no honoring
Information enabled on the input, all the traffic defaults to green drop precedence.
Related
wred-profile
Commands
trust

wred-ecn

Use explicit congestion notification (ECN) to indicate network congestion, rather than dropping packets.
E-Series, Z-Series, S4810
Syntax wred-ecn
To stop marking packets, use the no wred-ecn command.
Defaults none
Command Modes CONFIGURATION (conf-qos-policy-out)
Command History
Version 8.3.11.1
Version 8.3.7.0
Usage
When you enable wred-ecn, and the number of packets in the queue is below the minimum
Information
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 three scenarios can
occur:
When you enable wred-ecn, 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.
Introduced on the Z9000.
Introduced on the S4810.
Profile name character limit increased from 16 to 32.
Introduced on the .E-Series
– creates a WRED profile and name that profile.
– defines the dynamic classification to trust DSCP.
Introduced on the Z9000.
Introduced on the S4810.
• 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.
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