Section: 4.11.4.3.3 Initial Attach with GTP on S2b
Content: The procedure in clause 7.2.4 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] applies with the following modifications: - In Step A.1 IKEv2 tunnel establishment procedure, the 5GC NAS capable UE shall indicate its support of 5GC NAS in IKEv2. The UE allocates a PDU Session ID and also includes it in IKEv2 signalling sent to the ePDG. For 5GC NAS capable UE even if the NAS capability is currently disabled (i.e. N1 mode is disabled), the UE may also allocate a PDU Session ID and include it in IKEv2 signalling sent to the ePDG. - In Step A.1, UE's mobility restriction parameters related to 5GS or indication of support for interworking with 5GS for this APN or both as defined for MME in clause 4.11.0a.3 apply to the ePDG and are obtained by the ePDG as part of the reply from the HSS via the 3GPP AAA Server. These parameters and the 5G NAS support indicator from the UE, may be used by the ePDG to determine if a combined SMF+PGW-C or a standalone PGW should be selected. - In Step B.1, if the PDN connection is not restricted to interworking with 5GS by user subscription and if PDU Session ID is received from the UE, the ePDG shall send the 5GC Not Restricted Indication, 5GS Interworking Indication and the PDU Session ID to the SMF+PGW-C. - In Step B.1, if the SMF+PGW-C supports more than one S-NSSAI and the APN is valid for more than one S-NSSAI, the SMF+PGW-C selects S-NSSAI as specified in clause 4.11.0a.5. - In Step D.1 (Create Session Response), if the PDU Session ID is present and 5GC Not Restricted Indication is set, the SMF+PGW-C assigns a S-NSSAI to be associated with the PDN connection as specified in clause 5.15.7.1 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]. The SMF+PGW-C sends the S-NSSAI to the ePDG together with a PLMN ID that the S-NSSAI relates to. - In Steps B.1 and D.1, if the UE does not support 5GC NAS but has 5GS subscription and a SMF+PGW-C is selected and interaction with UDM, PCF and UPF is required, the SMF+PGW-C assigns PDU Session ID as specified in clause 4.11.0a.5. The SMF+PGW-C shall not provide any 5GS related parameters to the UE. - In the IKEv2 Authentication Response message, the ePDG sends S-NSSAI and the PLMN ID that the S-NSSAI relates to, to the UE. The UE associates the received S-NSSAI and the PLMN ID that the S-NSSAI relates to, with the PDN Connection. - After step D.1, the SMF+PGW-C provides the PCF ID selected for the PDN connection in the UDM using the Nudm_UECM_Registration service operation.