Restrictions for VLAN Tag-Based QoS
In a class map, you cannot specify the match-vlan command as the classification criteria if QoS
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services are defined for the corresponding traffic class in a child policy of a hierarchical policy.
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You can apply a child policy to any traffic class in a VLAN-group policy map. The child policy is
not restricted to being applied only to the class-default class.
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In a VLAN-group policy map, if you apply a child service policy to a traffic class of an input parent
policy, you must configure a non-queuing action such as policing before you apply the child policy.
You cannot configure any queuing actions for the parent class, such as shaping, priority, or
class-based weighted fair queuing (CBWFQ).
For example, consider the following sample configuration:
policy-map Input_Parent
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–
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Note
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For an output parent policy, the PRE2 allows you to configure only the shape command on the
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parent class. The PRE3 allows you to configure the shape command and the bandwidth remaining
ratio command on the parent class. The bandwidth remaining ratio command allows you to define
a proportionate share of the bandwidth for allocation to VLAN groups during periods of congestion.
You can configure the shape command and service-policy command for a traffic class of an output
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parent policy.
For example, the following sample configuration shows how to configure an output parent policy:
policy-map Egress_Parent
Cisco 10000 Series Router Quality of Service Configuration Guide
21-6
class vlangrp1
police percent 10
service-policy Child1
class vlangrp2
police percent 30
class vlangrp3
shape 512000
service-policy Child2
class vlangrp4
police 8000
service-policy Child3
The class vlangrp1 is a valid configuration for input traffic because it has a non-queuing action
(policing) defined before the Child1 service policy is applied.
The class vlangrp2 is a valid configuration because non-queuing actions are permitted for input
policies.
The class vlangrp3 is an invalid configuration for this input parent policy because it contains a
queuing action (shape).
If this was an output parent policy, the class vlangrp3 would be a valid configuration because
queuing actions such as shape are permitted for output policies.
The class vlangrp4 is a valid configuration for an input parent policy because it contains a
non-queuing action (police) before applying the child service policy.
class vgrp1
shape 128000
service-policy Child3
class vgrp2
shape 512000
service-policy Child2
class class-default
shape 2000000
service-policy Child1
Chapter 21
VLAN Tag-Based Quality of Service
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