5.28a.1 General

When the 5GS supports interworking with IEEE TSN deployed in the transport network, the CUC that is collocated with SMF interworks with the CNC in the transport network (TN CNC) as specified in clause 46.2 of IEEE Std 802.1Q [98]. The SMF/CUC provides the stream requirements on QoS Flow basis (i.e. translated Talker group and Listener group information) via the User/Network-Interface (UNI) to the TN CNC. The TN CNC uses the stream requirements as input to configure respective path(s) and schedules in TN. Based on the results, the TN CNC provides a Status group that contains the end station communication-configuration back to the SMF/CUC.

When interworking with TSN deployed in the transport network is applied, the dynamic value for the CN PDB of a Delay-critical GBR 5QI shall be considered as described in clause 5.7.3.4. When the SMF setups a new QoS Flow, the SMF signals TSCAI for the QoS Flow to NG-RAN on QoS Flow basis as described in clause 5.27.2.

Upon receiving the TSCAI for a QoS Flow from the SMF, if the TSCAI includes a BAT in UL direction and the dynamic value for the CN PDB is configured in the NG-RAN (as described in clause 5.7.3.4), the NG-RAN shall provide the 5G-AN PDB in the response to the QoS Flow request. The SMF/CUC uses 5G-AN-PDB to generate EarliestTransmitOffset as described in Annex M, clause M.1.

The details of providing End Station related information to generate the stream requirements for the QoS Flow by the SMF/CUC are described in Annex M, clause M.1.

If the NG-RAN and UPF support the TSN Talker and Listener functionality (i.e. implement the AN-TL and CN-TL, respectively), the SMF/CUC can communicate with the AN-TL and CN-TL via TL-Container. The TL-Container conveys the data sets defined in IEEE Std 802.1Qdj [146] between the SMF/CUC and AN-TL and CN-TL.

The AN-TL and CN-TL enable the following functions:

• hold and buffer functionality in a case when the TSCAI contains a BAT in UL and/or DL direction.
• support of stream transformation functionality with respective information exchange with SMF/CUC.
• for SMF/CUC to retrieve the InterfaceCapabilities and/or EndStationInterfaces from the AN-TL or CN-TL.
• topology information exchange functionality via LLDP in the TN as described in clause 5.28a.3.

NOTE 1: How to realize AN-TL in the base station and CN-TL in UPF is up to implementation.

NOTE 2: In this Release of the specification, it is assumed that connected mode mobility is not used in deployments with a TSN enabled TN.