21-6
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 21 VLAN Tag-Based Quality of Service
Restrictions for VLAN Tag-Based QoS
•
In a class map, you cannot specify the
match-vlan
command as the classification criteria if QoS
services are defined for the corresponding traffic class in a child policy of a hierarchical policy.
•
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.
•
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
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).
Note
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.
•
For an output parent policy, the PRE2 allows you to configure only the
shape
command on the
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
parent policy.
For example, the following sample configuration shows how to configure an output parent policy:
policy-map Egress_Parent
class vgrp1
shape 128000
service-policy Child3
class vgrp2
shape 512000
service-policy Child2
class class-default
shape 2000000
service-policy Child1
