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Subscribers Detachment in Services Control Gateway


Subscriber deletion is initiated by one of the following methods:

  • Accounting Stop from PGW

  • PCRF-initiated deletion

  • TDF-initiated deletion

    • Idle timer timeout

    • Clear subscribers from the CLI

    • TDF initiated subscriber deletion when PGW reboots

    • TDF initiated subscriber deletion when PCRF or OCS reboots

RADIUS Accounting Stop Messages Triggering Subscriber Deletion

The AAA process receives a steered Accounting Stop message from the ingress Packet Forwarding Engine. The AAA daemon triggers subscriber deletion towards SMD. The application framework processes this message and decides whether the subscriber needs to be deleted. The following steps illustrate subscriber deletion when an Accounting Stop message is received.

  1. Subscriber deletion is initiated with the Accounting Stopmessage received from the PGW. Packet Forwarding Engine forwards the accounting stop message received from the PGW to the AAA daemon.

  2. AAA forwards this message to the application function (AF). When all the bearers of the subscriber have been deleted, AF initiates the subscriber deletion finite state machine (FSM).

  3. AF notifies the backup session PIC about the subscriber deletion (delete intention)

  4. AF notifies the Gx module about the subscriber deletion. Gx sends a CCR-T message to the PCRF. Upon receiving the response from PCRF, Gx notifies the Traffic Flow Template (TFT) manager and the associated rules are deleted from the Packet Forwarding Engine.

  5. AF notifies the pfe manager to delete the subscriber from the Packet Forwarding Engine.

  6. AF notifies the service PIC and backup session PIC about the subscriber deletion (final deletion)

  7. Once all the modules have deleted the subscriber, AF deletes the subscriber from the Global IP table.

  8. SMD notifies the AAA daemon of the deletion completion and AAA daemon sends Accounting Stopresponse to PGW. In the other scenarios where TDF initiates the subscriber deletion or when the PCRF initiates the deletion, SMD deletes the subscriber and sends a deletion completion message to AAA daemon. Since TDF sends a CCR-T message to the PCRF during the deletion process, PCRF notifies the subscriber deletion to the PGW. Hence, subscriber deletion notification from TDF to the PGW is not needed.

Subscriber Session Update in a Services Control Gateway Network

Session Update can be initiated by

  • RAR message from PCRF.

  • Events generated on TDF such as Application-Start

Subscriber session update initiated by RAR from PCRF occurs in the following manner:

  1. PCRF initiates an RAR message with a set of rules to be added/modified/deleted. The Packet Forwarding Engine forwards this message to AAAD.

  2. AAAD forwards this message to AF.

  3. The AF module processes the RAR message and sends it to the Gx module. Gx processes this message.

  4. The new rules are synchronized to the backup session PIC.

  5. Gx processes the rules and programs the new rules on the services PIC.