Counter Subscription/Retrieval (N28 Session Creation)
This section describes the Counter Subscription/Retrieval (N28 Session Creation) call flow.
The decision to subscribe to N28 counters is determined based on the presence of the SpendingLimitRequest service configuration. If this service configuration is present in the policy, then the Policy Engine triggers the N28 session creation.

Note |
|
Step |
Description |
---|---|
1 |
The SMF sends a N7 Create request to the PCF. |
2 |
Based on the routing configuration, PCF configures the lookup or caches the CHF. |
3 |
If CHF is not found locally, then the PCF sends a Discover CH request to NRF. |
4 |
The NRF responds with the CHF profiles with the PCF. |
5 |
The PCF sends a N28 Subscribe request to the CHF. |
6 |
The CHF responds with the N28 Subscribe result to the PCF. |
7 |
The PCF performs the policy calculation. |
8 |
The PCF sends the N7 Create response after calculating the policy to the SMF. |