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Parameters
service-class Define the mapping between the service class and policy-
based QoS or routing.
wred Associate WRED with ECN to mark packets instead of
dropping them.
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
9.3.0.0 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. For the Z9500, you
can configure queues 0-7. 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
Quality of Service (QoS)
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