5G • Services
S-NSSAI
Single Network Slice Selection Assistance Information
The 3GPP identifier structure used to uniquely identify a specific network slice across 5G RAN and 5G Core.
Technical Explanation
An S-NSSAI is composed of an 8-bit Slice/Service Type (SST) and an optional 24-bit Slice Differentiator (SD). Standardized SST values include: SST=1 (eMBB), SST=2 (URLLC), SST=3 (MIoT/mMTC), SST=4 (V2X), SST=5 (High-performance Machine-Type). The SD provides operator-specific discrimination between multiple slices of the same service type (e.g., different enterprise customers requesting distinct URLLC slices). A collection of S-NSSAIs is called an NSSAI.
Key Functions
- Global identification of network slices during registration and session setup
- Signaled by UE in RRC and NAS establishment requests
- Assists AMF and NSSF in selecting slice-specific SMF and UPF instances
- Enables RAN scheduling policies mapped to slice priorities
Specifications
3GPP TS 23.501, TS 23.003
Interfaces
N1 (NAS)N2 (NGAP)Nnssf
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