4.6.2.6 Provision of NSAG information to lower layers

The support for NSAG information by the UE and the network, respectively, is optional. The NSAG information provided by the network and stored in the UE includes a list of NSAGs each of which contains:

• an NSAG ID;
• a list of S-NSSAI(s), which are associated with the NSAG and shall be part of the configured NSSAI;

NOTE 0: An alternative S-NSSAI is added to the configured NSSAI if not included yet.

• a priority value that is associated with the NSAG; and

NOTE 1: The AMF can take local configuration, UE 5GMM capabilities, subscribed S-NSSAIs, the mapping information between the S-NSSAI to be replaced and the alternative S-NSSAI, HPLMN, etc. to determine the NSAG priority information for the associated NSAG to a UE.

• optionally a list of TAIs in which the NSAG is valid. If it is not provided by the network, the NSAG is valid in the PLMN or SNPN which has sent the NSAG information and its equivalent PLMN(s).

NOTE 2: If the NSAG for the PLMN and its equivalent PLMN(s) have different associations with S-NSSAIs, then the AMF includes a list of TAIs in the NSAG information.

The UE NAS layer shall provide the lower layers with:

• the most recent NSAG information stored in the UE (see clause 4.6.2.2);
• the allowed NSSAI and the partially allowed NSSAI (if any) or the requested NSSAI for the purpose of network slice-based cell reselection (see 3GPP TS 23.501 [8]); and
• zero or more S-NSSAIs related to an access attempt for the purpose of network slice-based random access, when the access attempt is made by the UE in 5GMM-IDLE mode or 5GMM-CONNECTED mode with RRC inactive indication, determined as follows:
• requested NSSAI (if any), if an access attempt occurred due to the REGISTRATION REQUEST message;
• NSSAI(s) associated with all the PDU sessions included in the Uplink data status IE (if any), PDU session status IE (if any), or Allowed PDU session status IE (if any), if an access attempt occurred due to the SERVICE REQUEST message or CONTROL PLANE SERVICE REQUEST message;

iii) the S-NSSAI associated with the PDU session, if an access attempt occurred due to:

• an uplink user data packet to be sent for a PDU session with suspended user-plane resources;
• an UL NAS TRANSPORT which carries a 5GSM message for a PDU session associated with an S-NSSAI (if any); or
• CIoT user data to be sent in a CONTROL PLANE SERVICE REQUEST message or an UL NAS TRANSPORT message;
• no S-NSSAI, if an access attempt occurred due to:
• the deregistration procedure;
• a PDU session establishment request not associated with an S-NSSAI;
• the service request procedure for the UE-initiated NAS transport procedure for sending SMS, LPP message, UPP-CMI container, SLPP message, SOR transparent container, UE policy container, UE parameters update transparent container, or a location services message; or
• emergency services; or
• the allowed NSSAI (if any) and the partially allowed NSSAI (if any), if an access attempt occurred for other reason than those specified in bullets i) - iv).