Section: 6.2.14 NSSF
Content: The Network Slice Selection Function (NSSF) supports the following functionality: - Selecting the set of Network Slice instances serving the UE; - Determining the Allowed NSSAI and, if needed, the mapping to the Subscribed S-NSSAIs; - Determining the Configured NSSAI and, if needed, the mapping to the Subscribed S-NSSAIs; - Determining the AMF Set to be used to serve the UE, or, based on configuration, a list of candidate AMF(s), possibly by querying the NRF; - The NSSF may provide support for Network Slice restriction and Network Slice instance restriction based on NWDAF analytics. - Determining whether an S-NSSAI has to be replaced and providing to the AMF the indication that the S-NSSAI is unavailable and a corresponding Alternative S-NSSAI, e.g. based on received NWDAF analytics (e.g. for Service Experience for a Network Slice or Slice load level), or local trigger from the OAM system.