Administrator Guide

ecn Cause explicit congestion notification (ECN) to be used to indicate network congestion,
rather than dropping packets, queues-list Enter the queue numbers, either as individual
queue numbers separated by commas or as an inclusive list separating the starting and
ending queue numbers with a hyphen
queue-list Enter the port-queue numbers, either as individual queue numbers separated by commas
or as an inclusive list separating the starting and ending queue numbers with a hyphen; for
example, service-class wred ecn 0, 2, 4-6 backplane. The range of
queue IDs is 0 to 7.
backplane Specify that the ECN marking configured for each queue applies to backplane ports.
Default By default, ECN marking is disabled on all queues.
Command Modes CONFIGURATION mode
Command History
Version Description
9.9(0.0) Introduced on the C9010.
9.3.0.0 Introduced on the Z9500 switch.
9.3.0.0 Introduced on the Z9000 platform.
Usage Information You can add or remove ECN marking configuration on a list of queues on all backplane ports. All of the configured
attributes apply to all the backplane ports and are for each queue. You can configure all the data queues. You can
configure queues 0 to 7. By default, ECN marking is disabled on all queues. When you enable WRED with 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 with 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:
• If the transmission endpoints are ECN-capable and traffic is congested, and the WRED algorithm determines
that the packet should be 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
behavior 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 you
enable WRED with ECN and the number of packets in the queue is above the maximum threshold, packets are
dropped based on the drop probability. This behavior is the identical treatment a packet receives when WRED
is enabled without ECN configured on the router.
Example
Dell(conf)#service-class wred ecn 0, 3-5, 7 backplane
show qos dot1p-queue-mapping
Displays the dot1p priority to queue mapping on the switch.
C9000 Series
Syntax
show qos dot1p-queue-mapping
Defaults
• dot1p Priority: 0 1 2 3 4 5 6 7
• Queue: 0 0 0 1 2 3 3 3
Command Modes EXEC Privilege
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.
1356 Quality of Service (QoS)