Restrictions; Tail Drop And The Fifo Queue; How To Configure Modular Qos Congestion Avoidance On Cisco Ios Xr Software; Configuring Non-Weighted Random Early Detection - Cisco ASR 9000 Series Configuration Manual

Configuring Modular QoS Congestion Avoidance on Cisco ASR 9000 Series Routers

Restrictions

The following features are not supported by WRED for IPv4 multicast egress QoS traffic:
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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 on Cisco ASR 9000 Series Routers"
How to Configure Modular QoS Congestion Avoidance on
Cisco IOS XR Software
This section contains instructions for the following tasks:
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Configuring Non-weighted Random Early Detection

You can configure non-weighted Random Early Detection (RED) by not specifying IP precedence or any
other match criteria. 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 [default] command must be used to enable RED.
Restrictions
When configuring the random-detect dscp command, you must configure one of the following
commands: shape average, bandwidth, and bandwidth remaining.
SUMMARY STEPS
1.
2.
OL-17239-01
D r a f t — C i s c o C o n f i d e n t i a l
Classification other than DSCP or precedence.
Layer 3 set.
QoS is not active when packets go to the slow path. All packets go to the default queue.
IPv6 multicast.
"Default Traffic Class"
Configuring Non-weighted Random Early Detection, page 67
Configuring Weighted Random Early Detection, page 70
Configuring Tail Drop, page 73
Configuration Examples for Configuring Policy Maps, page 76
configure
policy-map policy-name
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide

How to Configure Modular QoS Congestion Avoidance on Cisco IOS XR Software

section of the "Configuring Modular Quality of Service Packet
module in this guide.
(required)
(required)
(required)
(optional)
QC-67