NSSF: slice selection logic

NSSF — The Slice Traffic Controller

The Network Slice Selection Function is the brain behind slice assignment in 5G. When a UE sends a Registration Request, the AMF may consult the NSSF to determine which S-NSSAIs to allow and which AMF set should serve this particular UE. The NSSF makes its decision by evaluating the UE's Requested NSSAI, the subscriber's Subscribed NSSAI from UDM, current network policy, and slice availability in the serving area. The AMF calls the NSSF via the Nnssf_NSSelection service operation during the registration procedure.