Content for  TS 23.402  Word version:  18.3.0

If dynamic PCC is deployed, the PCRF sends a PCC decision provision (QoS policy) message to the PDN-GW. This corresponds to the initial steps of the PCRF-Initiated IP-CAN Session Modification procedure or to the PCRF response in the PCEF initiated IP-CAN Session Modification procedure as defined in TS 23.203, up to the point that the PDN-GW requests IP-CAN Bearer Signalling. If dynamic PCC is not deployed, the PDN-GW may apply local QoS policy. The PCRF may also include a request to provide the User Location Info to the PDN-GW.

The PDN-GW uses this QoS policy to assign the EPS Bearer QoS, i.e., it assigns the values to the bearer level QoS parameters QCI, ARP, GBR and MBR. If this dedicated bearer is created as part of the handover from 3GPP access with GTP-based S5/S8, then the PDN-GW applies the Charging ID already in use for the corresponding dedicated bearer while the UE was in 3GPP access (i.e. bearer with the same QCI and ARP as in 3GPP access). Otherwise, the PGW generates a new Charging Id for the dedicated bearer. The PDN-GW sends a Create Bearer Request message (IMSI, EPS Bearer QoS, TFT, PDN-GW Address for the user plane, PDN-GW TEID of the user plane, Charging Id, LBI) to the ePDG. The Linked EPS Bearer Identity (LBI) is the EPS Bearer Identity of the default bearer. Steps 3 and 4 only applies if both the UE, and the ePDG support a separate IPsec SA per dedicated S2b bearer

The ePDG shall trigger an IKEv2 CREATE_CHILD_SA message, as defined in RFC 7296. The CREATE_CHILD_SA message shall contain an IKEv2 Notify Payload "TFT" that is a copy of the TFTs received over S2b in step 1. The CREATE_CHILD_SA message shall also contain an IKEv2 Notify Payload "Bearer QoS information".

The UE shall respond with CREATE-CHILD_SA-Response, and shall maintain a binding between the IPsec SA and the applicable TFT and bearer QoS information.

The ePDG selects an EPS Bearer Identity, which has not yet been assigned to the UE. The ePDG then stores the EPS Bearer Identity and links the dedicated bearer to the default bearer indicated by the Linked EPS Bearer Identity (LBI). The ePDG uses the uplink packet filter (UL TFT) and/or IPsec SA where applicable, to determine the mapping of uplink traffic flows to the S2b bearer. The ePDG then acknowledges the S2b bearer activation to the PGW by sending a Create Bearer Response (EPS Bearer Identity, ePDG Address for the user plane, ePDG TEID of the user plane, User Location Information) message. If the ePDG has established a IPsec SA association with the UE for a dedicated S2b bearer, it shall maintain a binding between the IPsec SA and the EPS bearer ID. The User Location Information shall include UE local IP address and optionally UDP or TCP source port number (if NAT is detected). It may also include WLAN Location Information (and its Age) the ePDG may have received from the 3GPP AAA server about the UE. When the PDN-GW receives no WLAN Location Information from the ePDG it shall delete any such information it may have stored for the PDN connection.

If the dedicated bearer activation procedure was triggered by a PCC Decision Provision message from the PCRF, the PDN-GW indicates to the PCRF whether the requested PCC decision (QoS policy) could be enforced or not, allowing the completion of the PCRF-Initiated IP-CAN Session Modification procedure or the PCEF initiated IP-CAN Session Modification procedure as defined in TS 23.203, after the completion of IP-CAN bearer signalling. If requested by the PCRF, the PDN-GW forwards to the PCRF following information extracted from User Location Information it may have received from the ePDG:

• WLAN location information in conjunction with the Age of this information,
• The UE local IP address and optionally UDP or TCP source port number (if NAT is detected).