5.28a Support of integration with TSN Transport Network

23.5013GPPRelease 18System architecture for the 5G System (5GS)TS

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 802.1Qcc [95]. 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 configured in the SMF as described in clause 5.7.3.4. When the SMF setups a new QoS Flow, the SMF signals the dynamic value for the CN PDB and TSCAI for the QoS Flow to NG-RAN on QoS Flow basis. Upon receiving the TSCAI for a QoS Flow from the SMF, if the TSCAI includes a BAT in UL direction, the RAN may determine a dynamic value of 5G-AN PDB in UL direction for the QoS Flow. The NG-RAN provides the dynamic value of 5G-AN PDB to the SMF in a response to the QoS Flow request. The dynamic value of 5G-AN PDB is used to generate EarliestTransmitOffset as described in Annex M.

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.

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 P802.1Qdj [146] between the SMF/CUC and AN-TL and CN-TL.

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

a) hold and buffer functionality in a case when the TSCAI contains a BAT in UL and/or DL direction.

b) support of stream transformation functionality with respective information exchange with SMF/CUC.

c) for SMF/CUC to retrieve the InterfaceCapabilities and/or EndStationInterfaces from the AN-TL or CN-TL.

d) topology information exchange functionality via LLDP in the TN as described in clause 5.28a.3.

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

5.28a.2 Transfer of TL-Container between SMF/CUC and AN-TL and CN-TL

When NG-RAN and UPF has signalled the support of AN-TL and CN-TL, the SMF/CUC may use the TL-Container to send a:

1) get-request.

2) set-request: submits the following elements of the Status group to the AN-TL or CN-TL:

– list of InterfaceConfiguration(s) (one InterfaceConfiguration is associated with each QFI in the N3 tunnel)

submits the following elements of Talker group to the AN-TL or CN-TL, as derived by the SMF/CUC:

– Interval.

– EarliestTransmitOffset.

– LatestTransmitOffset.

The AN-TL or CN-TL may use the TL-Container to send a:

1) get-response: indicates the following elements of the Talker or Listener group from the AN-TL or CN-TL:

– EndStationInterfaces: list of InterfaceIDs, one InterfaceID is associated with each Local F-TEID.

– InterfaceCapabilities.

– Buffer capability: maximum possible buffer duration supported by the Talker.

2) set-response: acknowledges the reception of the Status group to the SMF/CUC.

The SMF may request the UPF to report the support for AN-TL or CN-TL by including a TL-Container with a get-request to the AN-TL or CN-TN, respectively. The get-request is sent to AN-TL in the N2 SM information and to CN-TL in the N4 Session Establishment or Modification request as described in clause 4.3.2.2 of TS 23.502 [3].

If the NG-RAN/UPF supports AN-TL/CN-TL, the NG-RAN/AN-TL or UPF/CN-TL responds with a TL-Container including the elements defined for the get-response. The elements are associated with the corresponding N3 Tunnel Info (Local F-TEID) in the NG-RAN or UPF.

The SMF may submit TL-Container including a set-request the elements defined for the set-request to NG-RAN/AN-TL or UPF/CN-TL. The set-request is sent to AN-TL in the N2 SM information and to CN-TL in the N4 Session Establishment or Modification request as described in clause 4.3.2.2 of TS 23.502 [3]. The InterfaceConfiguration is associated with the corresponding QFI in the N3 tunnel in the NG-RAN or UPF, respectively. The AN-TL or CN-TL uses the provided configuration for the traffic in the QoS Flow of the given QFI as described in Annex M.

5.28a.3 Topology Information for TSN TN

NG-RAN and UPF may support u-plane LLDP functionality to provide topology information to the TN. When LLDP is supported, AN-TL and CN-TL are performing the LLDP functionality at the u-plane without the need to interact with the c-plane. Further there is no need for 5GS interaction with TN CNC directly. This is achieved with following measures:

– AN-TL and CN-TL implement the Transmit Only operation mode as defined in clause 9.1 of IEEE Std 802.1AB [97].

– The TSN End Station is pre-configured with parameter set for Transmit Only operating mode as defined in clause 9.2 of IEEE Std 802.1AB [97].

– The System Capabilities TLV may also be set to Station Only as defined in clause 8.5.8 of IEEE Std 802.1AB [97].