5G • Core Network
BSF
Binding Support Function
5GC discovery function that correlates user PDU sessions with the specific serving PCF instance.
Technical Explanation
In distributed networks with multiple PCFs, the BSF maintains binding information mapping a UE's IP/Ethernet address, SUPI, and DNN to the specific PCF serving that PDU session. Other NFs (e.g. AF, NEF, SMF) query BSF over the Nbsf interface to locate the authoritative PCF.
Key Functions
- Stores binding between UE IP address and serving PCF instance
- Enables Application Functions (AF) to locate the correct PCF
- Prevents policy conflicts in multi-PCF distributed cloud deployments
Specifications
3GPP TS 23.501, TS 29.521
Interfaces
Nbsf
Related 5G Concepts
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