Section: K.2.2 PTP Instance configuration K.2.2.1 General
Content: Based on input received from external applications (CNC in case of TSN AF or any AF in case of TSCTSF), TSN AF or TSCTSF may configure PTP instances (identified by PTP Instance ID) in a DS-TT or NW-TT by sending port management information (PMIC, see Table K.1-1) and user plane node management information (UMIC, see Table K.1-2) to DS-TT or NW-TT as described below: - use PMIC "PTP instance specification" for configuring DS-TT(s) for PTP instance data sets common for all PTP ports (i.e. defaultDS and TimePropertiesDS), and PTP instance data sets specific for each PTP port (i.e. portDS data set); - use UMIC "PTP instance specification" for configuring NW-TT for PTP instance data sets common for all PTP ports; - use PMIC "PTP instance specification" for configuring NW-TT for PTP instance data sets specific for each PTP port; - use UMIC "Time synchronization information for DS-TT ports" for configuring NW-TT for PTP instance data sets specific for each PTP port for the PTP ports in DS-TT(s). TSN AF or TSCTSF may also configure PTP instances for DS-TT ports in NW-TT by sending UMIC (see Table K.1-2) to NW-TT to enable NW-TT to operate as a grandmaster on behalf of DS-TT (see clause K.2.2.4 for more details). For each PTP instance the TSN AF or TSCTSF may provide individual PTP configuration parameters or may provide a PTP profile ID to DS-TT or NW-TT. The DS-TT and NW-TT use the default values as defined in the corresponding PTP Profile, if individual PTP configuration parameters that are covered by the PTP profile are not provided. NOTE 1: Even if PTP profiles are used to configure DS-TT or NW-TT, individual PTP parameters can still be configured in addition, e.g. domain numbers, transport to use, etc. To configure DS-TT and NW-TT to operate as a PTP relay instance, TSN AF or TSCTSF shall set the PTP profile (see Table K.1-1) to IEEE Std 802.1AS [104]. DS-TT may operate as a PTP relay instance with the gPTP GM connected on N6 until the first PTP instance is configured in the DS-TT by TSN AF or TSCTSF. To initialize a PTP instance in 5GS, TSN AF or TSCTSF creates a new PTP instance in NW-TT by assigning a new PTP Instance ID and indicating it to the NW-TT in "PTP instance specification" in UMIC and PMIC(s) for each NW-TT port that is part of the PTP instance. TSN AF or TSCTSF then retrieves the "defaultDS.clockIdentity" of the PTP instance in NW-TT via UMIC. NW-TT ensures that the clockIdentity in defaultDS in UMIC matches with the clockIdentity in the portDS.portIdentity in PMIC(s) for a particular PTP Instance ID. To add a DS-TT port into an existent PTP instance in 5GS, the TSN AF or TSCTSF indicates the PTP Instance ID (to which the DS-TT port is being added) to the DS-TT in "PTP instance specification" in PMIC, and indicating the PTP Instance ID to the NW-TT in "Time synchronization information for DS-TT ports" in UMIC for the corresponding DS-TT port. For a particular PTP instance in NW-TT, the same PTP Instance ID shall be used in "PTP instance specification" in PMIC, in "PTP instance specification" in UMIC, and in "Time synchronization information for DS-TT ports" in UMIC. NOTE 2: The TSN AF or TSCTSF creates a PTP Instance in the NW-TT or DS-TT by using the "Set parameter" operation code as described in TS 24.539[ 5G System (5GS); Network to TSN translator (TT) protocol aspects; Stage 3 ]  [139]. The NW-TT or DS-TT determines that this "Set parameter" operation creates a new PTP Instance based on the PTP Instance ID that does not correspond to any of the configured PTP Instances in the "PTP instance specification" and "Time synchronization information for DS-TT ports" (for NW-TT) or in the "PTP instance specification" (for DS-TT). The TSN AF or TSCTSF then initializes the PTP instance in the DS-TT by setting the applicable PTP instance data sets common for all PTP ports (i.e. defaultDS and TimePropertiesDS), (including"defaultDS.clockIdentity") via "PTP instance specification" in PMIC to the same value as retrieved from the NW-TT via "PTP instance specification" in UMIC. The TSN AF or TSCTSF also enables the PTP instance by setting the defaultDS.instanceEnable = TRUE to DS-TT via PMIC and to NW-TT via UMIC (if applicable). The TSN AF or TSCTSF can initialize any number of PTP instances: a) among the DS-TT(s) and NW-TT that are part of the same set of PTP instances in 5GS; up to the maximum number of supported PTP instances by the NW-TT or DS-TT that supports the lowest number of supported PTP instances; and b) in the NW-TT; up to the maximum number of supported PTP instances by the NW-TT. NOTE 3: How the TSN AF or TSCTSF assign NW-TT port(s) of one NW-TT to different PTP instances is up to implementation. To remove a DS-TT port from a PTP instance in 5GS, the TSN AF or TSCTSF deletes the PTP instance in DS-TT using PMIC and in NW-TT using UMIC as specified in TS 24.539[ 5G System (5GS); Network to TSN translator (TT) protocol aspects; Stage 3 ]  [139]. To remove a NW-TT port from a PTP instance in 5GS, the TSN AF or TSCTSF deletes the PTP instance in NW-TT using PMIC as specified in TS 24.539[ 5G System (5GS); Network to TSN translator (TT) protocol aspects; Stage 3 ]  [139]. If a PTP instance in 5GS is no more needed the TSN AF or TSCTSF may delete the PTP instance in NW-TT using UMIC as specified in TS 24.539[ 5G System (5GS); Network to TSN translator (TT) protocol aspects; Stage 3 ]  [139].