Editing RADIUS (section)

===Accounting===
[[File:Drawing RADIUS 1813.svg|thumb|350px|right|RADIUS Accounting Flow]]
Accounting is described in RFC 2866.

When network access is granted to the user by the [[Network access server|NAS]], an ''Accounting Start'' (a RADIUS Accounting Request packet containing an Acct-Status-Type attribute with the value "start") is sent by the NAS to the RADIUS server to signal the start of the user's network access. "Start" records typically contain the user's identification, network address, point of attachment and a unique session identifier.<ref>RFC 2866 RADIUS Accounting</ref>

Periodically, ''Interim Update'' records (a RADIUS Accounting Request packet containing an Acct-Status-Type attribute with the value "interim-update") may be sent by the NAS to the RADIUS server, to update it on the status of an active session. "Interim" records typically convey the current session duration and information on current data usage.

Finally, when the user's network access is closed, the NAS issues a final ''Accounting Stop'' record (a RADIUS Accounting Request packet containing an Acct-Status-Type attribute with the value "stop") to the RADIUS server, providing information on the final usage in terms of time, packets transferred, data transferred, reason for disconnect and other information related to the user's network access.

Typically, the client sends Accounting-Request packets until it receives an Accounting-Response acknowledgement, using some retry interval.

The primary purpose of this data is that the user can be [[Bill (payment)|billed]] accordingly; the data is also commonly used for [[statistical]] purposes and for general network monitoring.