Restrictions And Limitations For Three-Level Hierarchical Policies - Cisco 10000 Series Configuration Manual

Chapter 13 Defining QoS for Multiple Policy Levels

Restrictions and Limitations for Three-Level Hierarchical Policies

This section lists restrictions for three-level hierarchical policies. These restrictions might not apply to
Note
other types of hierarchical policies.
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Example 13-1
only those packets that also match its parent class map. In the example, the class map named Child
matches any packet that is not IP precedence 1 (for example, IP precedence 5). The class map named
Parent matches only IP precedence 1, 2, and 3. As a result, no packets from the Child and Parent classes
intersect.
Example 13-1 Improperly Defining Bottom-Level Child and Top-Level Parent Class Maps
Router(config)# class-map Parent
Router(config-cmap)# math ip precedence 1 2 3
!
Router(config)# class-map Child
Router(config-cmap)# match not ip precedence 1
Example 13-2
packets, which in
Example 13-2 Properly Defining Bottom-Level Child and Top-Level Parent Class Maps
Router(config)# class-map Parent
Router(config-cmap)# math ip precedence 1 2 3
!
Router(config)# class-map Child
Router(config-cmap)# match ip precedence 2 3
OL-7433-09
A top-level parent policy can have only the class-default class. Do not configure any other traffic
class.
The parent class-default class can have only the shape and service-policy commands configured.
Specify the shape command first and then the service-policy command to apply a child policy to
the parent policy.
A middle-level child policy cannot have the police and set commands configured. If you use these
commands in a middle-level policy, you cannot apply a bottom-level child policy to it using the
service-policy command.
A bottom-level child policy can have only the police and set commands configured for a class.
Each bottom-level class map must match only those packets that also match its parent class map. For
example, the union of the set of packets of a bottom-level class and that of its parent class must be
equal to the set of packets that match the parent class.
If a policy does not adhere to the above restriction, the router might incorrectly classify the
traffic affected by the policy.
shows a configuration that violates the requirement that the bottom-level class map match
modifies the configuration in
Example 13-2
Example 13-1
is IP precedence 2 and 3.
Cisco 10000 Series Router Quality of Service Configuration Guide
Types of Hierarchical Policies
to ensure the union of Child and Parent
13-9