Feature Description

During a session, if the User Plane function (UPF) is in congested state, it rejects the Packet Forwarding Control Protocol (PFCP) establishment messages from SMF with a cause code in the response message. To reduce call loss, the SMF retries to send PFCP establishment messages to a different UPF. Then, SMF selects a UPF based on priority (configuration) and capacity (load information from UPF).

The UPF failure handling support on N4 interface feature in SMF introduces a new failure handling template (FHT) profile for PFCP. This profile is associated with the UPF profile in SMF (in network elements).

The FHT template provides flexibility for SMF to fine tune its interactions with UPFs for sessions. It supports SMF to handle the error cause codes in response from UPF for both new and existing sessions. Based on the error cause codes in response from UPF, this feature provides the following configurable actions:

  • terminate

  • retry-terminate