3GPP 23.501 v20.2.0 — the document's own text

K.2.1 Capability exchange

Taught in 22. Clocks, TSN and deterministic delivery (The 5G system architecture, in depth).

DS-TT and NW-TT indicate time synchronization information they support inside the Port management capabilities (see Table K.1-1).

TSN AF and TSCTSF may determine the PTP functionalities supported by DS-TT and NW-TT by retrieving the following port management information or user plane node management information, respectively:

Supported PTP instance types;
Supported transport types;
Supported PTP delay mechanisms;
Grandmaster capability;
Supported PTP profiles;
Number of supported PTP instances.

NOTE: If NW-TT or DS-TT do not indicate support for any of the PTP profiles and PTP instance types, then TSN AF or TSCTSF assume that the NW-TT or DS-TT only support acting as a PTP Relay instance with the gPTP GM connected on N6.

If DS-TT and NW-TT support the PTP Relay instance type as defined by IEEE 802.1AS [104] then DS-TT and NW-TT shall include the IEEE 802.1AS [104] PTP profile in the "Supported PTP profiles" in PMIC and UMIC, respectively.

The TSN AF or TSCTSF may retrieve the "Number of supported PTP instances" from NW-TT via UMIC and from DS-TT via PMIC.