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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 10 Configuring Switch-Based Authentication
Controlling Switch Access with RADIUS

Session Identification

For disconnect and CoA requests targeted at a particular session, the switch locates the session based on
one or more of the following attributes:
• Calling-Station-Id (IETF attribute #31 which contains the host MAC address)
• Audit-Session-Id (Cisco VSA)
• Acct-Session-Id (IETF attribute #44)
Unless all session identification attributes included in the CoA message match the session, the switch
returns a Disconnect-NAK or CoA-NAK with the “Invalid Attribute Value” error-code attribute.
For disconnect and CoA requests targeted to a particular session, any one of the following session
identifiers can be used:
• Calling-Station-ID (IETF attribute #31, which should contain the MAC address)
• Audit-Session-ID (Cisco vendor-specific attribute)
• Accounting-Session-ID (IETF attribute #44).
If more than one session identification attribute is included in the message, all the attributes must match
the session or the switch returns a Disconnect- negative acknowledgement (NAK) or CoA-NAK with the
error code “Invalid Attribute Value.”
The packet format for a CoA Request code as defined in RFC 5176 consists of the fields: Code,
Identifier, Length, Authenticator, and Attributes in Type:Length:Value (TLV) format.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Authenticator |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attributes ...
+-+-+-+-+-+-+-+-+-+-+-+-+-
The attributes field is used to carry Cisco VSAs.

CoA ACK Response Code

If the authorization state is changed successfully, a positive acknowledgement (ACK) is sent. The
attributes returned within CoA ACK will vary based on the CoA Request and are discussed in individual
CoA Commands.

CoA NAK Response Code

A negative acknowledgement (NAK) indicates a failure to change the authorization state and can include
attributes that indicate the reason for the failure. Use show commands to verify a successful CoA.
CoA Request Commands
This section includes:
• Session Reauthentication