Configuring the UPF Failure Handling on N4 Interface

This section describes how to configure the UPF failure handling on N4 interface feature.

configure 
   profile failure-handling pfcp_name 
      interface pfcp message N4SessionEstablishmentReq 
      cause-code pfcp-entity-in-congestion 
      action retry-terminate max-retry value 
      end 

NOTES:

  • profile failure-handling: Specifies the UPF profile that is associated with FHT.

  • interface pfcp message {N4SessionEstablishmentReq | N4SessionModificationReq}: Specifies the failure handling for N4SessionEstablishmentReq (for new sessions) and N4SessionModificationReq messages (for existing sessions).

    Note

    UPF reselection is not applicable for message type N4SessionModificationReq because the session is already active on a UPF.

  • cause-code {pfcp-entity-in-congestion | mandatory-ie-incorrect | mandatory-ie-missing | session-ctx-not-found | system-failure | service-not-supported | no-resource-available | no-response-received | reject}: Specifies the error codes that SMF receives in the failure response message from UPF.

    Note
    • The no-response-received cause code is introduced in this feature to identify the scenarios where SMF does not receive any response from UPF.

    • FHT does not support the following cause codes, which are configured with their default behaviour:

      request-reject-unspecified , cond-ie-missing , invalid-length , invalid-fw-policy , invalid-fteid-alloc-opt , no-established-pfcp-assoc , rule-creation-mod-failure .
    • pfcp-entity-in-congestion: Specifies the cause code when UPF is congested.

    • reject: Specifies the option to handle the cause codes in the failure response message from UPF, which are not configured by using the CLI commands available for this feature.

  • action {retry-terminate | terminate}: Specifies the action to perform based on the error cause code received in the failure response message from UPF.

    • retry-terminate: Specifies a retry attempt to an alternate UPF. If the retry attempt fails, the session is terminated.

      Note

      If all UPFs are in congested state, call fails even if the action is set to continue.

    • max-retry: Specifies the number of retry attempts to reselect an alternate UPF.

      • Default value: 2

      • Maximum value: 5

Configuring the Failure Profile Association

This section describes how to configure the failure profile association in this feature.

configure 
   profile upf-group upf upf_group_name 
      failure-profile pfcp_name 
      end 

NOTES:

  • profile upf-group upf: Specifies the UPF group.

  • failure-profile: Specifies the FHT profile for PFCP.

Configuration Matrix

This section describes the configuration options available for N4 Session Establishment Request and N4 Session Modification Request messages in this feature.

Message Type Applicable Action Applicable Cause Code Default Behaviour
N4SessionEstablishmentReq retry-terminate
  • pfcp-entity-in-congestion

  • system-failure

  • service-not-supported

  • no-resource-available

  • no-response-received

terminate

N4SessionModificationReq

terminate

  • mandatory-ie-incorrect

  • session-ctx-not-found

  • no-response-received

continue