Dell C9000 series, Reference Manual

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Version Description
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.
Quality of Service (QoS) 1794