7.1 Introduction

23.2033GPPPolicy and charging control architectureRelease 17TS

The specification of the PCC procedures and flows is valid for the general scenario. Access specific information is included in Annex A, Annex D, Annex H and Annex P.

The description includes procedures for IP‑CAN Session Establishment, Modification and Termination. The IP‑CAN Session modification comprises IP‑CAN bearer establishment, modification, termination, as well as unsolicited PCC decisions.

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, as described in TS 23.401 [17] and the IP‑CAN specific Annexes, and non-3GPP accesses where GTP-based S2a or GTP-based S2b is employed, as described in TS 23.402 [18]).

Case 2: A Gateway Control Session is required. The BBERF establishes a Gateway Control Session prior to any IP‑CAN session establishment. There are two sub-cases:

2a) The UE acquires a care of address (CoA) that is used for the S2c reference point. The same Gateway Control session applies for all IP‑CAN sessions using that CoA.

2b) A Gateway Control Session is required, as described in TS 23.402 [18] and the IP‑CAN specific Annexes, Gateway Control Session Establishment, as defined in clause 7.7.1.
Each IP‑CAN session is handled in a separate Gateway Control Session.

The PCRF determines at Gx and Gxx session establishment what case applies initially as follows:

1. If the BBERF, at establishment of the Gateway Controls Session, provides an APN, then case 2b applies for the IP‑CAN session.

2. If the BBERF, at establishment of the Gateway Controls Session, does not provide any APN, then case 2a applies for the UE. For this case, the PCRF expects tunnelling header information for each IP‑CAN session to be provided by the applicable PCEF.

3. If there is no Gateway Control Session for the UE with the same IP‑CAN type as indicated over Gx, case 1 applies.

In a handover procedure the applicable case may change for an IP‑CAN session. The PCRF determines the new case in the same manner as described above. Details are defined in each such procedure.

The procedures cover non-roaming, roaming with home routed access and roaming with access to a visited PDN.

For the non-roaming case, the H‑PCRF plays the full role of PCRF. The V‑PCRF is not applicable in this case.

For the roaming case with home routed access, the H‑PCRF interacts with the PCEF and, if the Gxx applies, the V‑PCRF interacts with the BBERF.

For the roaming case with visited access (a.k.a. local breakout in TS 23.401 [17] and TS 23.402 [18]), the V‑PCRF interacts with the PCEF and, if Gxx applies, the BBERF and, if Sd applies, the TDF.

NOTE: The roaming scenario (figure 5.1-4) with visited access is not applicable for traffic steering control.

Procedures defined in this clause cover the traffic cases where the TDF is located on Gi/SGi interface.

Procedures defined in clause 7 cover all the traffic cases where roaming partners both operate PCC. For limited PCC deployment scenarios, Annex K and Annex L specify the impacts to these procedures.

In the text describing the steps in each sequence diagram, the designation PCRF, without specifying V‑ or H‑, refers to the PCRF in non-roaming case and refers to either the V‑PCRF or the H‑PCRF in the roaming cases. The interpretation of the text "PCRF" is thus dependent on the network scenario.

When NBIFOM (defined in TS 23.161 [43]) applies, the description of the flows in this clause 7 is complemented by the description of NBIFOM dedicated behaviours documented in clause 6.1.18.