Section: M.1 Mapping of the parameters between 5GS and TSN UNI
Content: Editor's note: The information provided here is a guidance for better understanding of the function. Content of this Annex will be updated to a functional level detail once stage 3 work is stable. The details of the parameters in the TSN UNI are specified in IEEE Std 802.1Q [98] and IEEE P802.1Qdj [146]. Stream identification is further specified in IEEE Std 802.1CB [83] and IEEE Std 802.1CBdb [178]. The SMF/CUC derives the End Station related information for the stream requirements towards the TN CNC for the QoS Flow as follows: a) For the Talker group: ‐ StreamID: can be generated by the SMF/CUC based on the End Station MAC address acting as Talker and a UniqueID. SUPI, PDU Session ID and QFI may be used to derive the UniqueID. The MAC address is either pre-configured at the SMF/CUC or provided by the AN-TL or CN-TL to the SMF/CUC (e.g. as part of the EndStationInterfaces information). - StreamRank: set to zero for ARP priority values 1-8; set to one for other ARP values. ‐ EndStationInterfaces: If the AN-TL and CN-TL are supported, the SMF/CUC receives the EndStationInterfaces (MacAddress, InterfaceName) from the AN-TL and CN-TL via TL-Container. If the AN-TL and CN-TL are not supported the SMF/CUC sets the information based on pre-configuration. - DataFrameSpecification (optional): When it is present it specifies how the TN can identify packets of the TN stream using Ethernet, IP and transport protocol header fields in order to apply the required TSN configuration. The SMF/CUC may derive the DataFrameSpecification based on: - N3 tunnel end point addresses that are used for the QoS Flow. The SMF/CUC may instruct the UPF and NG-RAN to assign a separate N3 tunnel end point address for each QoS Flow that may carry TSC streams so that the TN can distinguish the QoS Flows based on the N3 tunnel destination IP addresses. NOTE 1: IPv6 can be used in the N3 tunnel end point addresses to provide sufficient address space in case separate N3 tunnel end point addresses are used for each QoS flow that can carry time sensitive streams. - Mask-and-match stream identification parameters (IEEE 802.1CBdb [178] clause 9.1.6) (optional). The SMF/CUC may indicate mask-and-match configuration based on the TEID and QFI of the given QoS flow and the destination IP address to the TN CNC, when the deployment supports mask-and-match stream identification function as defined in clause 6.8 in IEEE Std 802.1CBdb [178]. This functionality can be used for example to check for the TEID and QFI in the GTP header and the destination IP address to distinguish the QoS Flows. This enables the TN CNC to configure the mask-and-match stream identification function in the transport network. This is an option that allows to use a single GTP-U tunnel as defined for non-TSN Transport networks. The DataFrameSpecification or mask-and-match stream identification parameters may be provided to the AN-TL and CN-TL to configure stream identification. In that case, the AN-TL and CN-TL can perform the stream identification without relying on additional information from the upper layers of the AN or CN node. When AN-TL and CN-TL are not supported the TN CNC configures the edge bridge to perform the stream transformation based on the provided the DataFrameSpecification or mask-and-match parameters when applicable. ‐ TrafficSpecification elements: ‐ Interval: derived from the Periodicity of the traffic as indicated in the TSCAI. ‐ MaxFramesPerInterval: specifies the maximum number of frames that the Talker transmits in one Interval. ‐ MaxFrameSize: derived from the MDBV of the QoS Flow. If the PCF determines interworking with a TSN network deployed in the transport network is supported based on the DNN/S-NSSAI of the PDU Session, the PCF generates MDBV based on the Burst Size as described in clause 5.27.3 and the PCF transfers the MDBV to the SMF/CUC. The SMF/CUC sets MaxFrameSize based on the following formula: MDBV of the QoS Flow - the framing bits which is not used for transferring in 5GS, (e.g. CRC + the GTP-U tunnel overhead). - TransmissionSelection: specifies the algorithm that the Talker uses to transmit the Stream's traffic class. If no algorithm is known, the value zero (strict priority) is used. ‐ TSpecTimeAware group (optional, present only if the traffic in the QoS Flow is time-synchronized): ‐ EarliestTransmitOffset: the earliest offset within the Interval. For uplink, EarliestTransmitOffset should be set based on the following formula: Packet arrival time at the Talker (UL) - M x Interval, where M is the largest integer for which the relation: Packet arrival time at the Talker (UL) > M x Interval duration. would be true. Packet arrival time at the Talker (UL) should be: TSCAC BAT in UL direction (presented in TAI time and corrected for clock drifting as specified in the present specification) + UE-DS-TT Residence Time. For downlink, EarliestTransmitOffset should be set based on the following formula: Packet arrival time at the Talker (DL) - M x Interval, where M is the largest integer for which the relation: Packet arrival time at the Talker (DL) > M x Interval duration. would be true. Packet arrival time at the Talker (DL) should be TSCAC BAT in DL direction (presented in TAI time and corrected for clock drifting as specified in the present specification). ‐ LatestTransmitOffset: the last chance within an interval should leave enough time to transfer a packet with MaxFrameSize. Derived from the end of the interval, the time to transfer a packet with MaxFrameSize. The LatestTransmitOffset shall be set to the Buffer Capability when the value of LatestTransmitOffset subtracted by the packet arrival time at the Talker (either UL or DL respectively as described in EarliestTransmitOffset) exceeds the Buffer capability. The value of LatestTransmitOffset shall be larger or equal than EarliestTransmitOffset. ‐ Jitter: derived in SMF/CUC based on local information on Jitter in AN-TL and CN-TL and respective stream and traffic interference. Annex U, clauses U.1.1, U.1.2, and U.1.3 of IEEE Std 802.1Q [98] provide some examples. ‐ UserToNetworkRequirements: ‐ NumSeamlessTrees: set to one (no redundancy) or other value (if redundancy is required). ‐ MaxLatency: set to CN PDB subtracted by maximum possible buffer duration in Talker. Maximum possible buffer duration is set to LatestTransmitOffset subtracted by EarliestTransmitOffset. - InterfaceCapabilities (optional): If the AN-TL and CN-TL are supported, the SMF/CUC collects InterfaceCapabilities from AN-TL and CN-TL via TL-Container. If the AN-TL and CN-TL are not supported, the SMF/CUC leaves the InterfaceCapabilities empty. b) For the Listener group: - Stream ID and Stream Rank: that were generated for the Talker of the TN stream are also used by the SMF/CUC for the Listener. - EndStationInterfaces: derived as with the corresponding information for the Talker group. - UserToNetworkRequirements: ‐ NumSeamlessTrees: set to one. ‐ MaxLatency: derived as with the corresponding information for the Talker group. - InterfaceCapabilities: derived as with the corresponding information for the Talker group. c) For the Status group: The Status group contains the end station communication-configuration provided by TN CNC to the SMF/CUC: ‐ Stream ID. ‐ StatusInfo. ‐ AccumulatedLatency: If the AccumulatedLatency is included from TN CNC to SMF/CUC for a stream in DL direction, the SMF/CUC may use the AccumulatedLatency to update the TSCAI BAT to the NG-RAN; the SMF sets the TSCAI Burst Arrival Time in downlink direction as the sum of the TSCAC BAT value in downlink direction and AccumulatedLatency and the buffer duration in Talker in CN-TL. The buffer duration in CN-TL is zero if TimeAwareOffset for the Talker group is not present, and TimeAwareOffset - EarliestTransmitOffset if the TimeAwareOffset is present for the Talker group. ‐ InterfaceConfiguration (optional): ‐ MAC Address (optional, present only if the respective InterfaceCapability contains a value for Active Destination MAC and VLAN Stream identification in CB-StreamIdenTypeList, and stream transformation is performed in AN-TL and CN-TL). ‐ VLAN Tag (optional, present only if the respective InterfaceCapability contains that it is VlanTagCapable and a value for Active Destination MAC and VLAN Stream identification in CB-StreamIdenTypeList, and the stream transformation is performed in AN-TL and CN-TL). ‐ IPv4/IPv6 Tuples (optional, but not supported in this release of the specification). ‐ TimeAwareOffset (optional, present only if the traffic is time-synchronized, AN-TL and CN-TL is supported, and TSpecTimeAware elements were provided in the stream requirements). If the InterfaceConfiguration is included and if the AL-TL/CN-TL acting as Talker End Station support the Stream Transformation as described in IEEE Std 802.1Q [98], the SMF/CUC can instruct the UPF and NG-RAN to assign an individual TSN Transport address by providing the InterfaceConfiguration to the AN-TL/CN-TL via TL-Container. The Talker in AN-TL/CN-TL shall use the indicated InterfaceConfiguration, e.g. source MAC address, multicast destination MAC address, VLAN ID, as assigned by the TN CNC for the data stream in a QoS Flow. The TN can identify the streams based on the Stream Transformation that is applied in the AN-TL/CN-TL acting as Taker End Station. This allows to use a single GTP-U tunnel as defined for non-TSN Transport networks. If the TimeAwareOffset is included from TN CNC to SMF/CUC, the SMF/CUC should send the TimeAwareOffset to the AN-TL (for streams in UL direction) or the CN-TL port (for streams in the DL direction). The AL-TL/CN-TL derive Gate Control information (i.e. AdminBaseTime, AdminCycleTime, AdminControlListLength, and AdminControlList) based on the TimeAwareOffset as defined in IEEE Std 802.1Q [98] at the AN-TL (for streams in UL direction) and the CN-TL port (for streams in the DL direction). The AN-TL or CN-TL acting as Talker buffers the data burst until the time indicated in the TimeAwareOffset is reached. If the SMF/CUC receives a TimeAwareOffset from TN CNC for a downlink stream (i.e. for a Talker in the UPF/CN-TL), the SMF/CUC adds the received TimeAwareOffset value to the TSCAI BAT in the DL direction in the TSCAI and updates the NG-RAN for the new TSCAI. ‐ FailedInterfaces (optional) provides a list of one or more physical ports of failed end stations or bridges to locate the interfaces in the physical topology that caused the failure. It is up to implementation how the SMF reacts when it receives FailedInterfaces. NOTE 2: It is assumed that the end station communication-configuration will contain at least the same information as defined for the status. NOTE 3: If Jitter value needs to be considered, EarliestTransmitOffset for UL and DL and LatestTransmitOffset shall be Jitter corrected. How Jitter correction is carried out is up to implementation.