Node-level Reporting Procedure due to GTP-u Path Failure Call Flow

When the UPF enables GTP-u Echo procedure for GTP-u endpoints and identifies a data path failure because of no response, it sends a PFCP Node Report Request to the SMF. The Node Report Type in the PFCP Node Report Request is set to User Plane Path Failure Report when it is sent to the SMF. The Node Report procedure includes only the peer IP address in Remote GTP-u Peer IE – the child IE of the User Plane Path Failure IE – since it is not specific to any PFCP session.

StepDescription
1Once the PFCP session is established and GTP-u Echo procedure is configured, UPF initiates the GTP-u Echo Request for each peer with at least one GTP-u Tunnel.
2If there is no GTP-u Echo Response received after a specified number of retries, then the UPF sends the PFCP Node Report Request to the SMF.
3Only the peer IP address is sent in the Node Report request since it is not a GTP-u tunnel-specific failure.
4Once the message is received, the SMF sends a Delete and Modify request for all the PFCP Sessions for that gNB to UPF.