S-NSSAI
Single Network Slice Selection Assistance Information: identifies a single network slice using SST (Slice/Service Type) and an optional SD (Slice Differentiator).
An S-NSSAI is the identifier for one network slice. It's built from two parts: a mandatory SST (Slice/Service Type, 8 bits) saying what kind of slice it is, and an optional SD (Slice Differentiator, 24 bits) that tells apart multiple slices of the same type. So SST=1 alone means "a generic eMBB slice," while SST=1, SD=000001 and SST=1, SD=000002 are two distinct eMBB slices — say, one per enterprise tenant.
One wrinkle worth knowing: an S-NSSAI can have different values on the two sides of a roaming boundary. There's a mapped S-NSSAI concept so the home and visited networks can line up their slice identifiers. On the job you'll see S-NSSAIs everywhere slicing touches the UE — in the NSSAI lists during registration, in subscription data, and tied one-to-one to each PDU session's slice.
Frequently asked questions
- What is the difference between SST and SD in an S-NSSAI?
- SST says what type of slice it is (the broad category — eMBB, URLLC, mMTC, etc.), and it is mandatory. SD is an optional sub-identifier that distinguishes multiple slices sharing the same SST, typically to separate tenants or services. SST answers "what kind of slice," SD answers "which specific one of that kind."
Related terms
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