PDU Session Resource Modify Unsuccessful Transfer IE

For each PDU session resource with the failed modification, NG-RAN includes PDU Session Resource Modify Unsuccessful Transfer IE of the PDU Session Resource Modify Request message. This message includes the cause value, with the details on cause for the unsuccessful modification, for SMF.

The PDU Session Resource Modify Unsuccessful Transfer IE includes the following causes and their cause values:

PDU Session Resource Modify Unsuccessful Transfer IE Causes and Cause Values
Cause Cause Value

Details

Radio Network Layer

Multiple PDU Session ID instances

NG-RAN includes this cause value after receiving the PDU Session Resource Modify Request message. This message includes various PDU Session ID IEs in the PDU Session Resource Modify Request List IE, with the same configured value.

Collision with Handovers

NG-RAN includes the following cause values after receiving the Handover request and continues with the Handover Preparation procedure:

  • NG intra-system handover triggered

  • NG inter-system handover triggered

  • Xn handover triggered

Note

The Handover request is necessary during the PDU Session Resource Modify procedure.

Unspecified

Note

For the preceding cause values, SMF stops the PDU Session Modification procedure and continues to use the same value for all the fields as existed in the earlier modification procedure. SMF maintains an N2 cause-based statistics under N2 message type.

Unknown PDU Session ID

NG-RAN includes this cause value after receiving the PDU Session Resource Modify Request message. This message includes PDU Session ID IEs, from the PDU Session Resource Modify Request List IE, which NG-RAN couldn't identify. These sessions are invalid PDU sessions.

SMF releases the PDU Session of the PDU Session IDs that NG-RAN marks as invalid or unknown. NG-RAN maintains a N2 cause-based statistics in the N2 message type.

Transport group

NG-RAN includes the transport cause value when the required transport resources are unavailable.

SMF stops the PDU Session Modification procedure and continues to use the same value for all the fields as existed in the earlier modification procedure. SMF maintains an N2 cause-based statistics in the N2 message type.

NAS

SMF stops the PDU Session Modification procedure and continues to use the same value for all the fields as existed in the earlier modification procedure. SMF maintains an N2 cause-based statistics in the N2 message type.

Protocol group

Miscellaneous

SMF triggers the release of the PDU Session after receiving the PDU Session Resource Modify Request message. This message includes the following Miscellaneous causes in N2 SM information. SMF maintains a N2 cause-based statistics in the N2 message type.

  • Hardware failure

  • Unknown PLMN

Except for the cause value of the preceding causes, SMF stops the PDU Session Modification procedure and continues to use the same value for all the fields as existed in the earlier modification procedure. SMF maintains an N2 cause-based statistics in the N2 message type.