PFCP Node Report Handling

For proper handling of PFCP node report, the GTP-U peer address must include a non-unique secondary session key. The Common Data Layer (CDL) stores the peer address and the UPF IP address along with the session details. If the GTP-U peer address changes during idle to active transition procedure, N2 handover (HO), 5G to 4G HO, or 4G to 5G HO, the CDL database deletes the old key and adds the new one.

  1. The UPF sends PFCP Node Report Request to the SMF along with the IP address of the failed GTP-U peer.

  2. The SMF protocol checks the node ID, that is, the UPF IP address included in the request. If the node ID is not found or if the node ID is not in associated state, the SMF protocol sends a failure response.

  3. If the node ID is found, the node manager queries the CDL for EPS session with the GTP-U peer IP address and node ID. The node manager sends bulk notification to the CDL to clear the corresponding sessions.

  4. The CDL sends the notification to rest endpoint (REST-EP) pod to clear the sessions.

  5. The REST-EP pod sends the subscriber clear notification to the SMF service based on the affinity. The SMF service clears the sessions on all interfaces.