Understanding RADIUS session records (CDRs)

This section explains the RADIUS session records or CDR (Call Detail Records) in more detail.

Whenever a user authentication via RADIUS server, the NAS device is responsible for sending session related data to the RADIUS server. This protocol is defined under RFC 2866 and is mandatory for all RADIUS servers.

On successful authentication process, the NAS initiated a Accounting Start packet to the radius server. This packet contains relevant information about the session like Username, MAC address of user, IP address of the user, Start Time, etc. The RADIUS server is responsible for storing this information and making it available to billing and accounting process.

While the session is in progress, the RADIUS server also sends interim information to the RADIUS server using Accounting Interim packets. It contains real-time information about the user's session like online time, upload and downloaded bytes. Once the RADIUS server receives the Interim packet, the information is updated in the CDR.

Lastly, the RADIUS server send Accounting Stop packet once the user's session is terminated. The RADIUS server is responsible for closing the CDR record and archiving it.

Following fields are available in the archived CDR records :

  • AcctSessionId : Session ID of the CDR
  • UserName : Username who logged in
  • NASIPAddress : IP address of the NAS gateway
  • AcctStartTime : Start time of the session
  • AcctStopTime : Stop time of the session
  • AcctSessionTime : Total online time in seconds
  • AcctInputOctets : Total number of bytes downloaded
  • AcctOutputOctets : Total number of bytes uploaded
  • CalledStationId : The MAC address of the NAS gateway
  • CallingStationId : The MAC address of the user's client
  • AcctTerminateCause : The reason for termination of the session
  • FramedProtocol : The protocol used for logging in
  • FramedIPAddress : The IP address of the client
  • LocationId : The location ID from where the user has logged in
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