Feature Description

SMF supports Final Unit Indication (FUI) in Credit Control Answer-Initial (CCA-I)/Credit Control Answer-Update (CCA-U) from the Online Charging System (OCS) to indicate that the given quota is the final quota from the server and the corresponding action as specified in the AVP must be taken.

Upon receiving the Final Unit Action (FUA), the SMF installs a new Forwarding Action Rules (FAR) and associate its FAR-ID in Usage Reporting Rule (URR). If a FAR with the same parameters already exists, the SMF uses its FAR-ID in create/update URR. The UPF takes an appropriate action as set in FAR after the quota exhaustion.

In case of Final Unit Action terminate, the SMF installs a new FAR with the application action “drop” and associate its FAR-ID in URR. The SMF will terminate the Protocol Data Unit (PDU) session immediately after reporting the final Used-Service-Unit to OCS without requesting further quota, if configured to terminate the session and, the quota is exhausted for that service/MSCC regardless of the state of the other MSCCs.

By default, the terminate configuration is not activated to terminate the session and the SMF will only report the final Used Service Unit to OCS without requesting further quota. The UPF should drop the further traffic after the quota exhaustion until OCS allocates the new quota through re-authorization.

Upon receiving further quota from the OCS after FUI activation, the previous FUI gets overwritten.

Note

Currently, the SMF with Gy interface supports only Terminate FU actions.

Levels of FUI

FUI exists at two levels:

  • Final Unit Indication at MSCC Level: If FUI is received at the MSCC level then the SMF terminates the session after the quota exhausts, only if the FUI CLI is configured to terminate the session. Also, if there is no quota and FUI is received, the SMF terminates the session immediately, only if the FUI CLI is configured to terminate the session.

  • Final Unit Indication at Command Level: If FUI is received at the Command level, the SMF terminates the session after quota exhaust irrespective of FUI CLI configuration. Also, if there is no quota and FUI is received, then the SMF terminates the session immediately.