RADIUS Accounting Packets

This section describes only the most important aspects of the RADIUS accounting packets. The RADIUS Accounting Request for Comment document (RFC 2866) provides detailed information on these packets.

RADIUS accounting packets can be divided into:

1. Accounting-Start packet contains userid, nas-identifier/ipaddress, plus other information received from the NAS.
2. Accounting-Stop record contains userid, nas-identifier/ipaddress, plus other information received from the NAS.
3. Accounting-On record contains nas-identifier/ipaddress record and indicates that a particular NAS has restarted.
4. Accounting-Off record contains nas-identifier/ipaddress record and indicates that a particular NAS has been shutdown.
5. Accounting-Interim record is an accounting record that could be received from the NAS. This record is sent periodically by the NAS for each user that is logged on at the NAS. This feature is generally supported in newer versions of NAS.

The following issues are important to consider when collecting accounting information made available through RADIUS: In rare cases, records could be lost during transmission and may never reach the RADIUS server.

1. The RADIUS server is not notified if the NAS aborts.
2. If the authentication and accounting requests are received from a RADIUS Proxy, then the other ISP may not forward accounting-on, off records.
3. ISDN supports multiple sessions and each session generates an accounting start/stop pair of records. There is an accounting attribute called multi-session identifier that clearly identifies such multi-session records. Check for the multi-session identifier in addition to the session identifier to calculate the number of sessions.

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Build date: 10/1/2007