Cisco 3032 - Page 210

7-22
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-12247-04
Chapter 7 Configuring Switch-Based Authentication
Controlling Switch Access with RADIUS
Preconditions
To use the CoA interface, a session must already exist on the switch. CoA can be used to identify a
session and enforce a disconnect request. The update affects only the specified session.
CoA Request Response Code
The CoA Request response code can be used to convey a command to the switch. The supported
commands are listed in Table 7-4 on page 7-23.
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.