Administrator Guide

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 9.3.0.0 Introduced on the S6000 and Z9000 platforms
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 Z9000, you can
configure queues 0-3. By default, ECN marking is disabled on all queues. When you
enable wred-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-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 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 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-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
Dellconf) #service-class wred ecn 0, 3-5, 7 backplane
service-class wred
The mechanism to configure a weight factor for WRED and ECN functionality for backplane ports is
supported on the Z9000 platform. Also, this mechanism to configure a weight for WRED and ECN
functionality for front-end ports is supported on the Z9000 platforms. Create a weighted random early
detection (WRED) profile and ECN functionality per queue granularity for backplane ports, and attach the
WRED profile with a service class. You can enable or disable these parameters for each queue and specify
minimum and maximum buffer thresholds for each color-coding of the packets. Also, you can specify
the maximum drop rate percentage for yellow and green profiles. The per-queue profile configured is
applicable to all the backplane ports.
Z9000
Syntax
[No] service-class wred {green | weight | yellow} {[queue0
number/string] || [queue1 number/string] || [queue2 number/
Quality of Service (QoS)
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