Content Filtering Policy ID on N7 Interface
The CF categories are configured under the active charging service under specific policy IDs. The rulebase and APN also have an associated policy ID. For any session, one policy ID can be associated with the session at anytime. The categories configured under that CF policy ID are applicable for the session on the UPF.
The PCF can override the CF policy ID by sending this value on the N7 interface. For this purpose, a proprietary IE is available in the YAML definition for the N7 interface. The hierarchy for the CF policy ID is as follows:
smPolicyDecision
ciscoAvpSet:
cfPolicyId: uint32 value
When the PCF does not send a CF policy ID, the existing CF policy ID in the rulebase configuration or the policy ID configured in the APN configuration is selected, in the order of precedence. This CF policy ID value is sent to the UPF in PFCP Session Establishment Request message in the "Subscriber Parameters" attribute. During PDU Session Modification, if the PCF changes the CF policy ID, the ID is sent to the UPF in PFCP Session Modification Request message.