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Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 24 Configuring QoS
Configuring Quality of Service (QoS)
This example shows how to create an ACL that permits IP traffic from a source host at 10.1.1.1 to a
destination host at 10.1.1.2:
Router(config)# access-list 100 permit ip host 10.1.1.1 host 10.1.1.2
Using Class Maps to Define a Traffic Class
You use the class-map global configuration command to name and to isolate a specific traffic flow (or
class) from all other traffic. A class map defines the criteria to use to match against a specific traffic flow
to further classify it. Match statements can include criteria such as CoS value, DSCP value, IP
precedence values, or QoS group values, or VLAN IDs. You define match criterion with one or more
match statements entered in the class-map configuration mode.
Follow these guidelines when configuring class maps:
• A match-all class map cannot have more than one classification criterion (one match statement), but
a match-any class map can contain multiple match statements.
• The match cos and match vlan commands are supported only on Layer 2 802.1Q trunk ports.
• You use a class map with the match vlan command in the parent policy in input hierarchical policy
maps for per-port, per-VLAN QoS on trunk ports. A policy is considered a parent policy map when
it has one or more of its classes associated with a child policy map. Each class within a parent policy
map is called a parent class. You can configure only the match vlan command in parent classes. You
cannot configure the match vlan command in classes within the child policy map.
• You cannot configure match qos-group for an input policy map.
• In an output policy map, no two class maps can have the same classification criteria; that is, the same
match qualifiers and values.
• The maximum number of class maps supported on the Cisco ASR 901 router is 256.
Complete the following steps to create a class map and to define the match criterion to classify traffic:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
class-map [match-all | match-any]
class-map-name
Create a class map, and enter class-map configuration mode. By default, no
class maps are defined.
• (Optional) Use the match-all keyword to perform a logical-AND of all
matching statements under this class map. All match criteria in the class
map must be matched.
• (Optional) Use the match-any keyword to perform a logical-OR of all
matching statements under this class map. One or more match criteria
must be matched.
• For class-map-name, specify the name of the class map.
If no matching statements are specified, the default is match-all.
Note A match-all class map cannot have more than one classification
criterion (match statement).