Synchronization does not work after switch of Master with optical switch
At BTrain lab, they have optical switch between two WR Switches,
usecase:
1. they had WRS-s connected with port 1 (slave) to WRS-m-1,
synchronization worked
2. they switched the hardware optical switch so that WRS-s is connected
to WRS-m-2 (possibly, the link did not go down). The servo stopped
updating (possibly PTP messages were discarded because they came from
different parent), yet, the PTP state was still SLAVE and the switch did
not recover