Configuring Modular QoS Congestion Avoidance on Cisco ASR 9000 Series Routers
How to Configure Modular QoS Congestion Avoidance on Cisco ASR 9000 Series Routers
QC-76
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide
OL-23108-02
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 “Default Traffic Class” section of the “Configuring Modular Quality of Service Packet
Classification and Marking on Cisco
ASR 9000 Series Routers” module.
How to Configure Modular QoS Congestion Avoidance on
Cisco
ASR 9000 Series Routers
This section contains instructions for the following tasks:
• Configuring Random Early Detection, page 76 (required)
• Configuring Weighted Random Early Detection, page 79 (required)
• Configuring Tail Drop, page 82 (required)
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:
• shape average
• bandwidth
• bandwidth remaining
SUMMARY STEPS
1. configure
2. policy-map policy-name
3. class class-name
4. random-detect {cos value | default | discard-class value | dscp value | exp value | precedence
value | min-threshold [units] max-threshold [units] }
To Next Page
Loading...
Need help?
General
