Section: 6.3.3.5 Abnormal cases on the network side
Content: The following abnormal cases can be identified: a) Expiry of timer T3592. The SMF shall, on the first expiry of the timer T3592, retransmit the PDU SESSION RELEASE COMMAND message and shall reset and start timer T3592. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3592, the SMF shall abort the procedure. b) Collision of network-requested PDU session release procedure and UE-requested PDU session modification procedure. When the SMF receives a PDU SESSION MODIFICATION REQUEST message during the network-requested PDU session release procedure, and the PDU session indicated in PDU SESSION MODIFICATION REQUEST message is the PDU session that the SMF had requested to release, the SMF shall ignore the PDU SESSION MODIFICATION REQUEST message and proceed with the PDU session release procedure. c) Collision of network-requested PDU session release procedure and UE-requested PDU session release procedure. If the SMF receives a PDU SESSION RELEASE REQUEST message after sending a PDU SESSION RELEASE COMMAND message with the PTI IE set to "No procedure transaction identity assigned" to the UE, and the PDU session ID in the PDU SESSION RELEASE REQUEST message is the same as the PDU session ID in the PDU SESSION RELEASE COMMAND message: - if the Access type IE is included in the PDU SESSION RELEASE COMMAND message and the PDU session is an MA PDU session and having user-plane resources established on the access different from the access indicated in the Access type IE in the PDU SESSION RELEASE COMMAND message, the SMF shall proceed both the UE-requested PDU session release procedure and network-requested PDU session release procedure; - otherwise, the SMF shall ignore the PDU SESSION RELEASE REQUEST message and proceed with the network-requested PDU session release procedure. d) Collision of re-establishment of the user-plane resources and network-requested PDU session release procedure for the same PDU session. If the SMF receives an indication from the AMF to re-establish the user-plane resources during the network-requested PDU session release procedure for the same PDU session, the SMF shall not re-establish the user-plane resources for the PDU session as specified in 3GPP TS 29.502[ 5G System; Session Management Services; Stage 3 ]  [20A] subclause 5.2.2.3.2.2 and proceed with the network-requested PDU session release procedure.