Configuring UPF Failure Handling Profile

To configure the UPF failure handling profile, use the following sample configuration:

config 
   profile failure-handling fh_profile_name 
      interface pfcp message { N4SessionEstablishmentReq | N4SessionModificationReq | N4SessionReportReq } 
         cause-code cause_ID 
         action { ignore | retry-terminate { max-retry retry_value } | terminate } 
         end 

NOTES:

  • profile failure-handling fh_profile_name : Specify the UPF failure handling profile name.

  • interface pfcp message { N4SessionEstablishmentReq | N4SessionModificationReq | N4SessionReportReq } : Specify the failure handling for N4SessionEstablishmentReq (for new sessions), N4SessionModificationReq messages (for existing sessions), and N4 Session Report Request.

    .

    Note

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

  • cause-code cause_ID : Specify the error codes that the SMF receives in the failure response message from the UPF.

    For the N4SessionEstablishmentReq and N4SessionModificationReq message types, the cause_ID must be one of the following values:

    • pfcp-entity-in-congestion : Specify this cause code when the UPF is congested.

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

    • no-response-received : Specify this option to determine 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 .

    For the N4SessionReportReq message type, the cause_ID must be an integer in the range of 2– 255. Separate the cause code value using either '-' or ',' or both. For example, cause-code 72-74,76,78-100

    When the N4SessionReportReq keyword is configured, the SMF triggers the Session Deletion Request followed by the rejection of Session Report. The UPF responds to the delete request and clears the session gracefully.

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

    • ignore —Specify to ignore the session. This FH action is applicable for N4SessionReportReq message type.

    • retry-terminate max-retry retry_value —Specify number of retry attempts to an alternate UPF. If the retry attempt fails, the session is terminated. This FH action is applicable for N4SessionEstablishmentReq message type.

      Default value: 2

      Maximum value: 5

      Note

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

    • terminate —Specify to terminate the session. This FH action is applicable for N4SessionEstablishmentReq, N4SessionModificationReq, and N4SessionReportReq message types.

      You can configure different failure handling conditions based on the procedures applicable only for the N4SessionModificationReq message type. To configure the conditions, use the following command:

      action terminate condition { handover-execution | handover-preparation | modify | idft | handover-cancel }

      Configuring the condition command is optional.

      Note

      The SMF allows configuration of one or more conditions for failure handling of N4 session modifications.

      The SMF either terminates or allows the existing session to continue according to the configured conditions. For example, if any of the handover execution procedures fail during N4 modification, the SMF terminates the session.

      The cause codes 0-255 are supported. Precedence of the cause codes are in the following order:

      1. Predefined string

      2. Number

      3. Range

      4. Reject

      Reject is the default cause code.

      The following table describes the configuration for cause codes:

      Configuration for Cause Codes
      Cause code Configuration

      0-63

      Corresponding template configuration

      64-255

      reject

Verifying the UPF Failure Handling Configuration

Use the show running-config command to view the configuration.

The following is an example output of the command.

show running-config profile failure-handling interface pfcp
profile failure-handling FH1
 interface pfcp message N4SessionEstablishmentReq
  cause-code pfcp-entity-in-congestion action retry-terminate max-retry 2
  cause-code system-failure action terminate
  cause-code service-not-supported action terminate
  cause-code no-resource-available action retry-terminate max-retry 3
  cause-code no-response-received action retry-terminate max-retry 1
  cause-code reject action terminate
 exit
 interface pfcp message N4SessionModificationReq
  cause-code mandatory-ie-incorrect action terminate
  cause-code session-ctx-not-found action terminate
  cause-code reject action terminate
 exit
 interface pfcp message N4SessionReportReq
  cause-code 69 action terminate
  cause-code 72-74,76,78-100 action terminate
 exit
exit