NSSF (Network Slice Selection Function)
Also known as: Network Slice Selection Function
The NSSF is the 5G core function that selects the set of network slice instances serving a UE and the appropriate AMF for a given registration request. It maps Requested/Allowed NSSAI to concrete slice instances based on subscription, roaming agreements and operator policy. Because slice selection determines which set of NFs a subscriber actually reaches, NSSF integrity is critical to slice isolation.
Categories: Core Network
NSSF in context
The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.
To place NSSF in the wider telecom-security picture, review NWDAF, Network Slice, Zero Trust (Telecom), Slice Hopping, BSF and URSP.
Related terms
Equipment
5G SBA control (NRF, SCP, NSSF, BSF, NWDAF)
Related topic hubs
- 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
- SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
- SS7 Firewall GSMA FS.11 category 1/2/3 SS7 message screening at the STP edge.
- SMS Firewall SMS spam, phishing, A2P bypass and MAP-layer SMS filtering.
More from the TelcoSec Glossary
Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.