Section: 5.27.1.5 Detection of (g)PTP Sync and Announce timeouts
Content: The procedure described in this clause is applicable when the PTP instance in 5GS is configured to operate as a time-aware system or as a Boundary Clock, and the PTP grandmaster is external to the 5GS, and the BMCA procedure (Method a) is used as described in clause 5.27.1.6. The NW-TT processes Announce messages according to IEEE Std 1588 [126]. In particular, the NW-TT shall compute and maintain the time when the Announce and Sync timeout events occur for the PTP port in a Follower state. When the 5GS is configured to operate as a time-aware system, the NW-TT shall determine the Sync and Announce message interval for the PTP Port at the other end of the link to which the Follower PTP Port in 5GS is attached, as described in IEEE Std 802.1AS [104]. When the 5GS is configured to operate as a Boundary Clock, the NW-TT shall determine Announce interval based on the configuration of the Follower port in 5GS, as described in IEEE Std 1588 [126]. The configuration of PTP instances in DS-TT and NW-TT for Sync and Announce timeouts is described in clause K.2. Upon detection of the Sync or Announce timeout event, the NW-TT shall re-evaluate the DS-TT and NW-TT port states as described in clause 5.27.1.6.