How To Configure Modular Qos Congestion Avoidance On Cisco Asr 9000 Series Routers; Configuring Random Early Detection - Cisco ASR 9000 Series Service Configuration Manual

How to Configure Modular QoS Congestion Avoidance on Cisco ASR 9000 Series Routers

Tail Drop and the FIFO Queue
Tail drop is a congestion avoidance technique that drops packets when an output queue is full until
congestion is eliminated. Tail drop treats all traffic flow equally and does not differentiate between
classes of service. It manages the packets that are unclassified, placed into a first-in, first-out (FIFO)
queue, and forwarded at a rate determined by the available underlying link bandwidth.
See the
Classification and Marking on Cisco ASR 9000 Series Routers"
How to Configure Modular QoS Congestion Avoidance on
Cisco ASR 9000 Series Routers
This section contains instructions for the following tasks:
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•
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Configuring Random Early Detection

You can configure Random Early Detection (RED) by configuring the random-detect command with
the default keyword on any class. In this way, a single RED profile is applied to all packets matching
the class.
This configuration task is similar to that used for WRED except that the random-detect precedence
command is not configured and the random-detect command with the default keyword must be used to
enable RED.
Restrictions
If you configure the random-detect default command on any class including class-default, you must
configure one of the following commands:
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•
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SUMMARY STEPS
1.
2.
3.
4.
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide
QC-76
"Default Traffic Class"
Configuring Random Early Detection, page 76
Configuring Weighted Random Early Detection, page 79
Configuring Tail Drop, page 82
shape average
bandwidth
bandwidth remaining
configure
policy-map policy-name
class class-name
random-detect {cos value | default | discard-class value | dscp value | exp value | precedence
value | min-threshold [units] max-threshold [units] }
Configuring Modular QoS Congestion Avoidance on Cisco ASR 9000 Series Routers
section of the "Configuring Modular Quality of Service Packet
(required)
(required)
module.
(required)
OL-23108-02