3GPP 23.501 v20.2.0 — the document's own text
6.2.10 AF
Taught in 4. What each network function does (The 5G system architecture, in depth), 2. Who does what in the core (The 5G system architecture, overview).
The Application Function (AF) interacts with the 3GPP Core Network in order to provide services, for example to support the following:
- Application Function influence on traffic routing (see clause 5.6.7);
- Application Function influence on Service Function Chaining (see clause 5.6.16.2);
- Accessing Network Exposure Function (see clause 5.20);
- Interacting with the Policy and charging control framework (see clause 5.14);
- Time synchronization service (see clause 5.27.1.8);
- IMS interactions with 5GC (see clause 5.16).
- Support PDU Set based Handling as defined in clause 5.37.5.
- Support Vertical Federated Learning (VFL) as VFL Server or VFL Client (see clause 5.4 of TS 23.288 [50]).
Based on operator deployment, Application Functions considered to be trusted by the operator can be allowed to interact directly with relevant Network Functions.
Application Functions not allowed by the operator to access directly the Network Functions shall use the external exposure framework (see clause 7.3) via the NEF to interact with relevant Network Functions.
The functionality and purpose of Application Functions are only defined in this specification with respect to their interaction with the 3GPP Core Network.