Section: 5.30.2.13 Access to SNPN services via Trusted non-3GPP access
Content: Access to SNPN services via Trusted non-3GPP access network follows the specification in the previous (sub)clauses of clause 5.30.2 with the differences as specified in this clause. To access SNPN services via a Trusted non-3GPP access network, the UE follows the procedure for accessing a PLMN via a Trusted non-3GPP access network defined in clause 6.3.12.2 with the following clarifications and additions: - A non-3GPP access network may advertise (e.g. with ANQP), not only the PLMNs with which 5G connectivity is supported (as specified in clause 6.3.12.2), but also the SNPNs with which 5G connectivity is supported and the related parameters and indications defined in clause 5.30.2.2 (i.e. human-readable network name(s), GIN(s), indication whether access using credentials from a Credentials Holder is supported, indication whether SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, etc.). - The UE initiates the access network selection procedure specified in clause 6.3.12.2 and constructs a list of available SNPNs. This list contains the SNPNs advertised by all discovered non-3GPP access networks. - The UE selects an SNPN that is included in the list of available SNPNs following the procedure in clause 5.30.2.4. - The UE selects a non-3GPP access network that supports 5G connectivity to the selected SNPN and initiates the registration procedure via Trusted non-3GPP access specified in clause 4.12a.2.2 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3] in order to register with the selected SNPN via the selected non-3GPP access network. During the EAP authentication procedure the NAI provided by the UE indicates that 5G connectivity to a specific SNPN is required (e.g. NAI = "<username>@nai.5gc.nid<NID>.mnc<MNC>.mcc<MCC>.3gppnetwork.org"). NOTE: In the case of SNPN ID with self-assigned NID, if the UE, when trying to register with an SNPN ID via TNAN X, is rejected by the AMF with a cause code that temporarily prevents the UE from registering with this SNPN ID, the UE does temporarily not attempt to register with the same SNPN ID, even if the same SNPN ID is advertised via another TNAN. - If there are multiple non-3GPP access networks that support 5G connectivity to the selected SNPN, then the UE places these non-3GPP access networks in a prioritized list and selects the highest priority non-3GPP access network from this list. To determine the priority of a non-3GPP access network, the UE shall apply the WLANSP rules (if provided), and the procedure specified in clause 6.6.1.3 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [45], "UE procedure for selecting a WLAN access based on WLANSP rules". If the UE is not provided with WLANSP rules, the UE determines the priority of a non-3GPP access network by using implementation means. UE onboarding via Trusted non-3GPP access is supported as follows: - The non-3GPP access network advertises (e.g. via ANQP) an Onboarding enabled indication, as specified in clause 5.30.2.10.2.3. - The UE selects an SNPN advertising the Onboarding enabled indication following the network selection procedure specified in clause 5.30.2.10.2.5. - As part of UE registration via Trusted non-3GPP access, in Figure 4.12a.2.2-1, step 5 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3] the UE provides an onboarding indication inside the AN-Parameters.