5.15.4.1.2 Mapping of S-NSSAIs values in the Allowed NSSAI and in the Requested NSSAI to the S-NSSAIs values used in the HPLMN

For the roaming case, one or more S-NSSAIs in an Allowed NSSAI provided to the UE can have values which are not part of the UE's current Network Slice configuration information for the Serving PLMN. In this case, the network provides the Allowed NSSAI together with the mapping of each S-NSSAI of the Allowed NSSAI to the corresponding S-NSSAI of the HPLMN. This mapping information allows the UE to associate Applications to S-NSSAIs of the HPLMN as per NSSP of the URSP rules or as per the UE Local Configuration, as defined in clause 6.1.2.2.1 of TS 23.503 [45] and to the corresponding S-NSSAI from the Allowed NSSAI.

In the non-roaming case and if the Serving PLMN ID is the same as the PLMN ID of the SUPI, the network shall not provide any mapped S-NSSAI to the UE with the Allowed NSSAI. In the non-roaming case and if the Serving PLMN ID is not the same as the PLMN ID of the SUPI, the network shall provide the mapped S-NSSAI of the HPLMN to the UE with the Allowed NSSAI if different values are used for S-NSSAI in Serving PLMN and mapped S-NSSAI in HPLMN.

NOTE: It is recommended that the Serving PLMN and the HPLMN use the same S-NSSAI values in this case.

The UE shall provide in the Requested NSSAI the mapping of S-NSSAIs of the Serving PLMN values to the corresponding S-NSSAI values of the HPLMN, for each S-NSSAI in the Requested NSSAI for which a mapping is available. These values are found in the mapping previously received from the Serving PLMN of the S-NSSAIs of the Configured NSSAI for the Serving PLMN or of the S-NSSAIs of the Allowed NSSAI for the Serving PLMN and Access Type to the corresponding S-NSSAIs values used in the HPLMN.

If the AMF provides Partially Allowed NSSAI to the UE, in roaming case the AMF may provide the mapping information of each S-NSSAI of the Partially Allowed NSSAI to the corresponding HPLMN S-NSSAI as described in clause 5.15.17.