4.0 General

29.2133GPPPolicy and charging control signalling flows and Quality of Service (QoS) parameter mappingRelease 17TS

There are three distinct network scenarios for an IP-CAN Session:

Case 1. No Gateway Control Session is required, no Gateway Control Establishment occurs at all (e.g. 3GPP Access where GTP-based S5/S8 are employed, and Non-3GPP access where GTP-based S2a or GTP-based S2b is employed).

Case 2. A Gateway Control Session is required. There are two subcases:

2a) The BBERF assigns a Care of Address (CoA) to the UE and establishes a Gateway Control Session prior to any IP-CAN session establishment that will apply for all IP-CAN sessions using that CoA.

2b) At IP-CAN session establishment a Gateway Control Session is required before the PCEF announces the IP-CAN Session to the PCRF. At BBERF change and pre-registration the Gateway Control Session shall match an IP-CAN session that the PCEF has already announced. Each IP-CAN session is handled in a separate Gateway Control Session.

The PCRF shall select whether case 2a or case 2b applies based on the information received in the Gateway Control Session Establishment. For a user identified with a Subscription-Id AVP, when the PDN identifier included as part of the Called-Station-Id AVP is received, case 2b applies. If not received, case 2a applies.

The following considerations shall be taken into account when interpreting the signalling flows:

– V-PCRF is included to also cover the roaming scenarios.

– H-PCRF will act as a PCRF for non-roaming Ues.

– The steps numbered as “number+letter” (e.g. “3a”) will be executed, for the roaming case, instead of steps numbered as “number” (e.g. “3”), as indicated in the explanatory text below the signalling flows.

– Emergency services and RLOS are handled locally in the serving network, therefore the S9 reference point does not apply.

NOTE: For the Visited Access case, the operator can by roaming agreement decide not to use S9 reference point.

The procedure to detect that the Gx session or a Gateway Control Session is restricted to Emergency Services is described in 3GPP TS 29.212 [9].

– The procedure to detect that the Gx session is restricted to RLOS is described in 3GPP TS 29.212 [9].

– Subscription-related information is not relevant for the policy control of Emergency Sessions and RLOS; therefore Sp reference point does not apply in that case.

– With the UDC-based architecture as defined in 3GPP TS 23.203 [2] and 3GPP TS 23.335 [51], SPR, whenever mentioned in the present specification, refers to UDR. The Ud interface as defined in 3GPP TS 29.335 [52] is the interface between the PCRF and the UDR.

– When monitoring event reporting via PCRF applies as defined in 3GPP TS 23.682 [38], the SCEF is acting as an AF. In this case, only the flows where the AF is located in the home network apply. Support of this functionality is detailed in 3GPP TS 29.214 [10], Annex D.

– If the PCEF/BBERF/TDF needs to send an IP-CAN session/ Gateway Control Session/ TDF session modification request towards a PCRF which is known to have restarted since the IP-CAN session/ Gateway Control Session/ TDF session establishment, the PCEF/BBERF/TDF shall follow the PCRF Failure and Restoration procedure as defined in 3GPP TS 29.212 [9].

NOTE: Only the interaction with OCS for spending limits reporting over Sy interface is introduced in this document.

– The PCEF and TDF are depicted as monolithic entities in the signalling flows, but each of those can be decomposed into a User Plane Function and a Control Plane Function connected via the Sx reference point. Signalling on the Sx reference point is not shown.