PDU Session Resource Setup Unsuccessful Transfer IE

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

In case the serving NG-RAN doesn't accept the partial QoS Flow failures of a PDU Session, the SMF initiates the PDU Session Modification procedure. This procedure removes the non-accepted QoS flows from the PDU Session after PDU Setup procedure is completed.

Note

SMF supports the decoding of "Criticality Diagnostics" IE that it receives as part of the N2 message only. For example, PDU Session Resource Setup Unsuccessful Transfer message and PDU Session Resource Modify Unsuccessful Transfer message. SMF doesn't fully support the "Criticality Diagnostics" IE for other messages.

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

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

Description

Radio Network Layer

Multiple PDU Session ID instances

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

User Plane Security Enforcement

NG-RAN includes the following cause values in case the User Plane Security Enforcement information is unfulfilled. These cause values have either the Required or Preferred value:

  • UP integrity protection not possible

  • UP confidentiality protection not possible

  • UE maximum integrity protected data rate reason

Collision with Handovers

NG-RAN includes the following cause value 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 PDU Session Resource Setup procedure.

Note

For the preceding cause values, in case of failure detection, if the NG-RAN doesn't forward N1 message to UE and continues with the session release, the SMF sends the PDU Session Establishment Reject message toward UE through N1 message. NG-RAN maintains the N2 cause-based statistics in the N2 message type.

Unspecified

In case the NG-RAN failure is unspecified, SMF triggers the release of this PDU Session. NG-RAN maintains a N2 cause-based statistics in the N2 message type.

Protocol Group

Erroneous errors in Protocol data

NG-RAN includes the following cause values when it couldn't decode the received message:

  • Transfer syntax error

  • Abstract syntax error (reject)

  • Abstract syntax error (falsely constructed message)

  • Semantic error

Note

If the NG-RAN doesn't forward N1 message to UE and continues with the session release, the SMF sends the PDU Session Establishment Reject message toward UE through N1 message. NG-RAN maintains the N2 cause-based statistics in the N2 message type.

Unforeseen or Unknown information in Protocol data

NG-RAN includes the following cause value when it is unable to decode the received message:

  • Message not compatible with receiver state

  • Unspecified

  • Abstract syntax error (ignore and notify)

When the NG-RAN is unable to decode the message, SMF triggers the release of the PDU Session. NG-RAN maintains an N2 cause-based statistics in the N2 message type.

Transport Group

Inaccessible transport resources

NG-RAN includes the following cause values when required transport resources are unavailable:

  • Resource Unavailable

  • Unspecified

When the NG-RAN is unable to access the transport resources, SMF triggers the release of the PDU Session. NG-RAN maintains an N2 cause-based statistics in the N2 message type.

Miscellaneous

Not enough user plane processing resources

NG-RAN includes this cause value when insufficient resources are available for the User Plane processing.

When the NG-RAN is unable to access the User Plane processing resources, SMF triggers the release of the PDU Session. NG-RAN maintains an N2 cause-based statistics in the N2 message type.