Section: 4.11.4.3.6 Use of N10 interface instead of S6b
Content: This clause applies to scnearios when ePDG is connected to SMF+PGW-C and S6b in not used. It is applicable for procedures specified in TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] including mobility between EPC/ePDG and EPC/EUTRAN and also for mobility between EPC/ePDG and 5GS. When S6b, as specified in TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], is not deployed between SMF+PGW-C and AAA and the UE creates and deletes a PDN connection via ePDG connected to SMF+PGW-C, the registration and de-registration of PDN GW is performed on the N10 interface instead of the S6b interface. If SMF+PGW-C is selected for a UE that does not support 5GC NAS, the SMF+PGW-C determines the PDU Session ID and S-NSSAI in the same way as for PDN connection via EPC/EUTRAN as specified in clause 4.11.0a.5. For roaming scenario with local-breakout (TS 23.501[ System architecture for the 5G System (5GS) ]  [2], Figure 4.3.4.2.1), the use of N10 interface instead of S6b interface may be based on support of this feature from HSS+UDM to SMF+PGW-C on N10 interface. The specific impacts to procedures in clauses 7 and 8 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] are as follows: 7.2.4 Initial Attach with GTP on S2b - Instead of Step C.1 in Figure 7.2.4-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], step 16c (Nudm_UECM_Registration with an optional indication that access is from ePDG) from Figure 4.3.2.2.1-1 are performed between the SMF+PGW-C and HSS+UDM. Based on this indication, the HSS+UDM does not send notification of PGW-C assignment on SWx to AAA. 7.2.5 Initial Attach for emergency session (GTP on S2b) - Instead of step 5 in Figure 7.2.5-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], step 16c (Nudm_UECM_Registration with an optional indication that access is from ePDG) from Figure 4.3.2.2.1-1 are performed between the SMF+PGW-C and HSS+UDM. Based on this indication, the HSS+UDM does not send notification of PGW-C assignment on SWx to AAA. The indication of access from ePDG is forwarded on the interface between UDM and HSS. 7.4.3 UE/ePDG-initiated Detach Procedure and UE-Requested PDN Disconnection with GTP on S2b 7.4.3.1 Non-Roaming, Home Routed Roaming and Local Breakout Case - Instead of Step A.2 in Figure 7.4.3-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], step 12 (Nudm_UECM_Deregistration) from Figure 4.3.4.2-1 is performed between the SMF+PGW-C and HSS+UDM. 7.4.4 HSS/AAA-initiated Detach Procedure with GTP on S2b 7.4.4.1 Non-Roaming, Home Routed Roaming and Local Breakout Case - Instead of step 3 in Figure 7.4.1-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] (referenced by Figure 7.4.4-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26]), Step 12 (Nudm_UECM_Deregistration) from Figure 4.3.4.2-1 is performed between the SMF+PGW-C and HSS+UDM 7.9.2 PDN GW initiated Resource Allocation Deactivation with GTP on S2b - Instead of step 5 in Figure 7.9.2-1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], Step 12 (Nudm_UECM_Deregistration) from Figure 4.3.4.2-1 is performed between the SMF+PGW-C and HSS+UDM. 8.6.1.1 General Procedure for GTP based S5/S8 for E-UTRAN Access - Step 18 of clause 8.6.1.1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] refers to clause 7.9.2 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26]. The Nudm_UECM_Deregistration in the impacted referenced clause 7.9.2 above is not performed as resources in the SMF+PGW-C are not released. 8.6.2.1 3GPP Access to Untrusted Non-3GPP IP Access Handover with GTP on S2b - In Step B.2 of clause 8.6.2.1 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26], if the registration of the SMF+PGW-C in the HSS+UDM is not already done, step 16c (Nudm_UECM_Registration with an optional indication that access is from ePDG) from Figure 4.3.2.2.1-1 is performed between the SMF+PGW-C and HSS+UDM. The impacts to procedure in clause 4.11.4.1 (Handover from EPC/ePDG to 5GS) are as follows: - For step 0, the impacts to clause 7.2.4 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] are captured above. - In step 2, if the Request Type indicates "Existing Emergency PDU Session", the AMF shall use the Emergency Information containing SMF+PGW-C FQDN for the S2b interface and the S NSSAI locally configured in Emergency Configuration Data. - In step 3, the impacts to clause 7.9.2 of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] are captured above. Nudm_UECM_Deregistration is not performed by SMF+PGW-C, as resources in the SMF+PGW-C are not released. The impacts to procedures in clause 4.11.4.2 (Handover from 5GS to EPC/ePDG) are as follows: - For step 2, impacts to clause 8.6.2.1 (3GPP Access to Untrusted Non-3GPP IP Access Handover with GTP on S2b) of TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [26] are captured above and Step 16c of Figure 4.3.2.2.1-1 is not performed as SMF+PGW-C already registered in the HSS+UDM when the UE is in 5GS.