NF Registration and NF Update Call Flow
The following figure illustrates the call flow representing the NF registration and NF update messaging from SMF on NF profile change trigger from REST-EP.

-
The SMF REST-EP, on start-up, reads the SMF profile configuration and accordingly populates the NF management profile. The REST-EP then triggers SMF to indicate the NF Profile change.
-
The SMF maintains the NF registration status and the registered profile in an external cache pod. The SMF detects whether the NF registration with NRF is completed. If the SMF detects that the registration is not completed during NF profile change handling, perform Step 3. If the NF registration is complete, perform Step 4.
-
The SMF sends NF Register to NRF. It allows an NF instance to register its NF profile in the NRF. It includes the registration of the general parameters of the NF instance along with the list of services exposed by the NF instance.
-
The SMF fetches the registered NF profile and then compares it with the new profile.
-
The SMF sends NF update (PUT) request to the NRF when any of the parameters in the NF management profile changes due to SMF profile configuration change.
Load parameter is not set as part of the PUT message. Heartbeat is set as the current active heartbeat interval.
-
The SMF ignores the trigger if there is no change detected.
ImportantThe NF update is sent only from the elected SMF.