Configuring Modular QoS Service Packet Classification and Marking on Cisco ASR 9000 Series Routers
Information About Configuring Modular QoS Packet Classification and Marking on Cisco ASR 9000 Series Routers
QC-12
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide
OL-23108-02
A traffic class contains three major elements: a name, a series of match commands, and, if more than
one match command exists in the traffic class, an instruction on how to evaluate these match commands.
The traffic class is named in the class-map command. For example, if you use the word cisco with the
class-map command, the traffic class would be named cisco.
The match commands are used to specify various criteria for classifying packets. Packets are checked
to determine whether they match the criteria specified in the match commands. If a packet matches the
specified criteria, that packet is considered a member of the class and is forwarded according to the QoS
specifications set in the traffic policy. Packets that fail to meet any of the matching criteria are classified
as members of the default traffic class. See the
“Default Traffic Class” section on page 12.
The instruction on how to evaluate these match commands needs to be specified if more than one match
criterion exists in the traffic class. The evaluation instruction is specified with the class-map match-any
command. If the match-any option is specified as the evaluation instruction, the traffic being evaluated
by the traffic class must match at least one of the specified criteria. If the match-all option is specified,
the traffic must match all of the match criteria.
The function of these commands is described more thoroughly in the Cisco ASR 9000 Series
Aggregation
Services Routers Modular Quality of Service Command Reference. The traffic class
configuration task is described in the
“Creating a Traffic Class” section on page 19.
Traffic Policy Elements
The purpose of a traffic policy is to configure the QoS features that should be associated with the traffic
that has been classified in a user-specified traffic class or classes. The policy-map command is used to
create a traffic policy. A traffic policy contains three elements: a name, a traffic class (specified with the
class command), and the QoS policies. The name of a traffic policy is specified in the policy map
Modular Quality of Service (MQC) (for example, the policy-map policy1 command creates a traffic
policy named policy1). The traffic class that is used to classify traffic to the specified traffic policy is
defined in class map configuration mode. After choosing the traffic class that is used to classify traffic
to the traffic policy, the user can enter the QoS features to apply to the classified traffic.
The MQC does not necessarily require that users associate only one traffic class to one traffic policy.
When packets match to more than one match criterion, as many as 1024 traffic classes can be associated
to a single traffic policy. The 1024 class maps include the default class and the classes of the child
policies, if any.
The order in which classes are configured in a policy map is important. The match rules of the classes
are programmed into the TCAM in the order in which the classes are specified in a policy map.
Therefore, if a packet can possibly match multiple classes, only the first matching class is returned and
the corresponding policy is applied.
The function of these commands is described more thoroughly in the Cisco ASR 9000 Series
Aggregation Services Router Modular Quality of Service Command Reference.
The traffic policy configuration task is described in the “Creating a Traffic Policy” section on page 22.
Default Traffic Class
Unclassified traffic (traffic that does not meet the match criteria specified in the traffic classes) is treated
as belonging to the default traffic class.
If the user does not configure a default class, packets are still treated as members of the default class.
However, by default, the default class has no enabled features. Therefore, packets belonging to a default
class with no configured features have no QoS functionality. These packets are then placed into a first
To Next Page
Loading...
Need help?
General
