UPF: User Plane Function
UPF processes and forwards user data to/from SMF.
It will connect to external data networks.
It will generate charging data records and traffic usage records.
It is capabe of performing packet inspection and apply configured policies.
UPF applies QoS policies on packets in Downlink Direction.
UPF resembles SGW and PGW.
There can be multiple UPF in series.
UDM: Unified Data Mangement
Frontend for Unified Data Repository (UDR). It will store all the subscription information.
UDM uses subscription data to perform access authorization, registration management and rechability for events like SMS.
UDM generates auth credentials used during auth process.
UDM keeps track of which AMF is serving a user.
UDM is always located in home PLMN.
UDM is similar to HSS.
UDR: Unified Data Repository
It is the repository for all subscription information and all data related to user policies
UDR provides services to other network functions like IDM, PCF, NEF(Network Exposure Function).
AUSF: Authentication Server Function
5G – EIR (Equipment ID Registry)
Checks if the device is valid or not
PCF: Policy Control Function
PCF will provide policy control for session management related functionality.
It will provide functionality for access and mobility realted functionality.
PCF will interacts with Application Functions and SMF to provide autorized QOS.
PCF will interact with AMF for access and mobility policy control.
PCF will also interact with UE via NAS(AMF) to provide network slice selection policy, Session Continuuty Mode selection policy.
NRF: Network Repository Function.
NRF will hold the repository of the profiles of Network Functions that are availabe in the network.
The purpose of NRF is to allow the consumer to discover and select suitable producers.