When the target UE is connected to the 5G core network via non-3GPP access, the POIs present in the following NFs of the PLMN where the N3IWF resides provide the LI functions:
When the PLMN that has the N3IWF is the HPLMN, as illustrated in clause A.1
, the IRI-POI present in the UDM also provide the LI functions.
When the PLMN that has N3IWF is different from the PLMN that provides the 3GPP access to the target UE, two different AMFs are involved in handling the target UE's registration accepts (this is not illustrated in this clause). In this case, depending on the operator policy, the SMSF present in either of the two networks may perform the routing of SMS messages to and from the target UE.
The PLMN that provides the 3GPP access can be a VPLMN and PLMN where the N3IWF resides can be the HPLMN. In this case, the AMF in the HPLMN provides the IRI-POI functions for non-3GPP access related registration events when the target UE is roaming. The SMSF present in the HPLMN may have to provide the IRI-POI functions for the SMS related messages routed via non-3GPP access network.
The overall network configuration for non-3GPP access in a non-roaming scenario with the LI aspects is shown in figure A.4-1. In this view, the target UE is not connected to a 3GPP access network.
The 5G core system is shown using the service-based representation (as shown in TS 23.501
) with the use of point-to-point LI system.
Figure A.4-1 shows the network topology of 5G system in a service-based representation, however, all the LI-related interfaces remain to be point-to-point.
The IRI-POIs present in the AMF, UDM, SMSF and SMF deliver the xIRI to the MDF2 and CC-POI present in the UPF delivers the xCC to the MDF3. The MDF3 address to CC-POI present in UPF is provided by the CC-TF present in the SMF over LI_T3 reference point.
The LIPF present in the ADMF provisions the IRI-POIs present in the NFs with the intercept related data. The LI_X1 interfaces between the LIPF and the UPF is to monitor the user plane data.