Cisco Cisco IOS Software Release 12.2(27)SBC

Cisco AV pairs are part of vendor-specific attributes (VSAs) that allow a policy map to be applied to the 
LNS. Cisco AV pairs are a combination of an attribute and a value. The purpose of Cisco VSA (attribute 
26) is to communicate vendor-specific information between the LNS and the RADIUS server. The Cisco 
VSA encapsulates vendor-specific attributes that allow vendors such as Cisco to support their own 
extended attributes. 

For this configuration, one of two Cisco AV pairs can be used (formatted as shown below):

lcp:interface-config=service-policy output/input <policy name>

This Cisco AV pair is considered a “legacy” AV pair. It is of earlier origin but is still an available 
choice. 

sub-qos-policy-in/out=<policy name>

This Cisco AV pair takes advantage of more recent technology and is the recommended choice. This 
Cisco AV pair is the one shown in the configuration tasks and examples.

The Cisco AV pair is added to the subscriber’s user file on the RADIUS server. A subscriber’s user file 
contains an entry for each user that the RADIUS server will authenticate. Each entry establishes an 
attribute the user can access. 

When looking at a user file, the data to the left of the equal sign (=) is an attribute defined in the 
dictionary file, and the data to the right of the equal sign is the configuration data.

The Cisco AV pair identifies the policy map that was used to configure the specific QoS features. When 
the LNS requests the policy map name (specified in the Cisco AV pair), the policy map is pulled to the 
LNS from the RADIUS server when the session is established. The Cisco AV pair applies the appropriate 
policy map (and, therefore, the QoS feature) directly to the LNS from the RADIUS server. 

Authentication, authorization, and accounting (AAA) must be enabled.

The RADIUS server must be configured.

The subscriber’s user profile on the RADIUS server must be created.

The PPP session is established. 

A policy map is configured.