3 Cloud Native Core Network Functions

The 4G/5G Network Funtions that are part of this document are following:

Table 3-1 5G Network Functions

Network Functions	Abbreviation	Description
Network Repository Function	NRF	NRF provides registration, discovery and authorization services to all the Network Functions (NF) in the 5G core network.
Service Communication Proxy	SCP	SCP provides a 5G-aware service mesh. The SCP is not a part of the current 3GPP 5G specification, but is expected to be added to a future iteration.
InterWorking Function	IWF	IWF provides 4G/5G inter-working support.
Network Slice Selection Function	NSSF	NSSF works with the Access and Mobility Function (AMF) to select the network slice to be used by the User Equipment (UE).
Security Edge Protection Proxy	SEPP	In the roaming architecture, the home and the visited network are connected through Security Protection Proxy (SEPP) for the control plane of the internetwork interconnect.
Unified Data Repository	UDR/UDSF	UDR is a repository of subscriber information, and is used by various NFs (including UDR, PCF, and NEF). The UDSF is a part of the Unified Data Management Function (UDF) and is used to store state information for Network Functions (NF).
Unified Data Management/Authentication Server Function	UDM/AUSF	UDM uses the subscription data stored in UDR and implements the application logic to perform various functionalities such as authentication credential generation, user identification, service and session continuity etc. The Authentication Server Function (AUSF) uses data stored in the UDM to perform authentication.
Network Exposure Function	NEF	Securely exposes network capabilities and events to Application Functions (AF).
Cloud Native Core Policy	CNC Policy	The CNC Policy is a functional element for policy control decision and flows based charging control functionalities.
Binding Support Function	BSF	Provides PCF binding (mapping and selection) for User Equipment (UE).

Table 3-2 4G Network Functions

Network Functions	Abbreviation	Description
Cloud Native 4G Diameter Routing Agent Network	cnDRA	Provides core (subset) 4G DSR capabilities delivered in a CNE microservice.