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TDF Subscriber Management Using RADIUS Accounting Messages


Subscriber management functionality includes the creation, update and deletion of the subscribers while interacting with various modules in this process. Subscriber creation in a Services Control Gateway network is initiated by the Accounting start message received from the subscriber edge network element.

RADIUS Accounting-Start Message Triggering Subscriber Creation

The ingress Packet Forwarding Engine on Service Control Gateway receives a RADIUS accounting start message and steers accounting start message to the AAA process. The AAA daemon or process invokes AF API, if a new subscriber must be created.

The following sequence of events occur during the subscriber creation:

  1. Packet Forwarding Engine steers the Accounting-start message from subscriber edge network element to AAA. AAA processes the message and triggers session create event.

  2. Mobile subscriber management daemon (mobile-smd) receives session create message from AAA. The create message contains IP address, VRF APN and IMSI for wireless subscribers. Mobile-smd performs the following steps:

    • Checks for the existing session for the given IP address and VRF.

    • For new sessions, Tdf-service is obtained from the service selection profile using either the Apn or the IP address-range from the configuration. If no service selection profile exists, default tdf-service is applied.

    • Mobile-smd updates the global {IP VRF} table through RCM module with the information received in the session create message.(IPv4/v6, IMSI if available)

    • Mobile-smd selects the service PIC based on the IP address chunk in LAM.

    AF in mobile-smd sends a request to Gx to initiate Gx session creation and waits for the response from Gx.

  3. Rules information is synchronized to backup session PIC.

  4. PCC rules are programmed in the service Packet Forwarding Engine if the support is available.

  5. Application function (AF) in mobile-smd sends request to Gy to initiate Gy session creation and waits for the response from Gy. By default, the name of the file that records trace output for mobile charging is mobile-smd.

  6. Subscriber record is synced to backup session PIC.

  7. Mobile-smd informs Packet Forwarding Engine manager to program the subscriber record in service Packet Forwarding Engine if it is supported.

  8. Subscriber record and rules are updated in the Service PIC. Success response is sent to AAA after the successful completion of all the previous steps.

  9. AAA receives session create response from SMD and generates Accounting response to be sent to PGW.


    In case of an error condition at any stage during the processing of the create request, respective resources are deallocated and appropriate error response is sent to AAA.