6.2.9 Traffic Detection Function (TDF)

23.2033GPPPolicy and charging control architectureRelease 17TS General

The TDF is a functional entity that performs application detection and reporting of detected application and its service data flow description to the PCRF. The TDF supports solicited application reporting and/or unsolicited application reporting. The application detection filter may be extended with the PFDs provided by the PFDF as described in clause 6.1.20. The new PFDs provided by the PFDF replace the existing ones in the PCEF.

The TDF shall detect Start and Stop of the application traffic for the ADC rules that the PCRF has activated at the TDF (solicited application reporting) or which are pre-provisioned at the TDF (unsolicited application reporting). The TDF shall report, unless the notification is muted for the specific ADC Rule in case of solicited application reporting, to the PCRF:

– For the Start of application event trigger: the application identifier and, when service data flow descriptions are deducible, the application instance identifier and the service data flow descriptions to use for detecting that application traffic with a dynamic PCC rule as defined in clause 6.1.4.

– For the Stop of application event trigger: the application identifier and if the application instance identifier was reported for the Start, also the application instance identifier as defined in the clause 6.1.4.

For solicited application reporting, the PCRF can request the TDF to also perform enforcement actions, charging and usage monitoring.

For those cases where service data flow description is not possible to be provided by the TDF to the PCRF, the TDF performs:

– Gating;

– Redirection;

– Bandwidth limitation;

– Charging.

for the detected applications.

For those cases where service data flow description is provided by the TDF to the PCRF the actions resulting of application detection may be performed by the PCEF as part of the charging and policy enforcement per service data flow as defined in this document or may be performed by the TDF.

NOTE: The PCEF can be enhanced with application detection and control feature as specified in clause

The TDF shall support usage monitoring as specified in clause 4.4 and the usage reporting functions as specified in clause for the PCEF.

The TDF shall support data volume, duration, combined volume/duration and event based measurement for charging. The Measurement method indicates what measurement type is applicable for the ADC rule.

NOTE 1: Events to be charged are predefined in the TDF.

The TDF measurement measures all the user plane traffic, except packets discarded by ADC-rule enforcement or due to MBR-enforcement.

The TDF shall maintain a measurement per TDF session and Charging Key combination.

If Service identifier level reporting is mandated in an ADC rule, the TDF shall maintain a measurement for that Charging Key and Service identifier combination, for the TDF session.

If there are required events which cannot be monitored in the TDF (e.g. related to the location changes), the TDF shall request the information about these Event Triggers from the PCRF using either:

– The IP-CAN Session Establishment procedure, as defined in clause 7.2, or

– The PCEF initiated IP-CAN Session Modification procedure, as defined in clause 7.4.1, or

– In the response to a PCRF initiated IP-CAN Session Modification, as defined in clause 7.4.2, or

– Within the Update of the subscription information in the PCRF procedure, as defined in clause 7.5.

For unsolicited application reporting, the TDF performs only application detection and reporting functionality but neither enforcement actions nor usage monitoring. The TDF should handle each IPv4 address and IPv6 prefix, assuming the max prefix length used in the access network, within a separate TDF session. The PCRF shall, if needed, correlate TDF sessions that correspond to the same IP-CAN session.

The TDF shall support traffic steering as specified in clause 6.1.17. Traffic steering

When the PCRF provides a Traffic Steering Policy Identifier(s) in an ADC rule, the TDF shall enforce the referenced traffic steering policy for the application. A traffic steering policy is locally configured and can be used for the uplink, the downlink or for both directions.

To enforce the traffic steering policy, the TDF performs deployment specific actions as configured for that traffic steering policy. The TDF may for example perform packet marking where, for the traffic identified by the Application Identifier or by the service data flow filter list (defined by an active ADC rule), the TDF provides information for traffic steering, as part of the packets, to the (S)Gi-LAN. This information for traffic steering identifies, explicitly or implicitly, a specific set of service functions and their order via which the traffic needs to be steered in the (S)Gi-LAN.