Notification of Counter Changes from CHF
In case of changes in the subscribed policy counters, the CHF notifies PCF using the Nchf_SpendingLimitControl_Notify operation. The PCF supports this operation through the PCF REST endpoint.
On receiving the notification, the REST EP performs a datastore lookup to determine the route and then forward the notification message to the selected engine group.
On the PCF Engine, the existing session is updated with the new counter information and policy is recalculated (using the new VS) and applicable decisions are pushed on the N7 interface towards SMF via N7 Notify operation.

Step |
Description |
---|---|
1 |
If the N7 and N28 sessions are available, then CHF sends a N28 Notify request to the PCF. |
2 |
After the N28 session is updated with the new information, the policy is recalculated and the updated session is saved in the CDL. |
3 |
The PCF sends a N7 Update Notification message to the SMF. |
4 |
The SMF sends response for the N7 Update Notification message to the PCF. |
5 |
The PCF sends a N28 Notification Success response to the CHF. |