Section: 6.4.1.7 Abnormal cases on the network side
Content: The following abnormal cases can be identified: a) If the received request type is "initial emergency request" and there is an existing emergency PDU session for the UE, regardless whether the PDU session ID in the PDU SESSION ESTABLISHMENT REQUEST message is identical to the PDU session ID of the existing PDU session, the SMF shall locally release the existing emergency PDU session and proceed the new PDU SESSION ESTABLISHMENT REQUEST message b) The information for the PDU session authentication and authorization by the external DN in PDU DN request container is not compliant with local policy and user's subscription data If the PDU session being established is a non-emergency PDU session, the request type is not set to "existing PDU session", the PDU session authentication and authorization by the external DN is required due to local policy and user's subscription data and the information for the PDU session authentication and authorization by the external DN in the SM PDU DN request container IE is not compliant with the local policy and user's subscription data, the SMF shall reject the PDU session establishment request including the 5GSM cause #29 "user authentication or authorization failed", in the PDU SESSION ESTABLISHMENT REJECT message. c) UE-requested PDU session establishment with request type set to "initial request" for an existing PDU session: If the SMF receives a PDU SESSION ESTABLISHMENT REQUEST message with a PDU session ID identical to the PDU session ID of an existing PDU session and with request type set to "initial request", the SMF shall locally release the existing PDU session and proceed with the PDU session establishment procedure. d) UE-requested PDU session establishment with request type "existing PDU session" or "existing emergency PDU session" for a PDU session that does not exist: If the SMF receives a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "existing PDU session" or "existing emergency PDU session", and the SMF does not have any information about that PDU session, then the SMF shall reject the PDU session establishment procedure with the 5GSM cause set to #54 "PDU session does not exist" in the PDU SESSION ESTABLISHMENT REJECT message. e) 5G access network cannot forward the message: If the SMF determines based on content of the n2SmInfo attribute specified in 3GPP TS 29.502[ 5G System; Session Management Services; Stage 3 ]  [20A] that the DL NAS TRANSPORT message carrying the PDU SESSION ESTABLISHMENT ACCEPT was not forwarded to the UE by the 5G access network, then the SMF shall reject the PDU session establishment procedure with the 5GSM cause set to #26 "insufficient resources" in the PDU SESSION ESTABLISHMENT REJECT message.