Bridge Technologies VB440 - A Appendix: PTP and BMCA

There are usually five different types of clocks that are mentioned in relation to PTP.
The first three are defined as ordinary clocks and the last two are used by different
types of switches or routers.
The VB440 always acts as a slave clock only, and it will not show other slave clocks.
The clocks shown will be clocks which present themselves as master clocks, this
includes boundary clocks. The chosen grandmaster will at all times be marked with a
star under Preferences  in the PTP clock section.
In order to accommodate the PTP client and BMCA, the setup for PTP in expert view
must be correct. The following configurable fields are available:
- Mode
- Domain number (0-127)
- Priority1 (0-255)
- Sync Interval (-7 to -1)
Slave clock only
Will always act like a slave and receive
time from a master clock.
Preferred grand master
Only acts as a master. It has the ability
to get standard time, for example from a
GPS receiver.
Master clock or slave clock
This is a device that can act as a slave
or a master. It usually starts out in a
slave state, but has the possibility to
become a master in case there are no
better suited masters on the network.
Transparent clock
A switch that simply adds its own
switching delay to passing PTP packets.
Boundary clock
A Switch that receives sync messages
from an upstream ptp master clock on
its slave port and synchronizes its
internal clock to it and generates a new
sync message to its master ports.
A Appendix: PTP and BMCA
VB440 Studio Probe User’s Manual v6.0 © Bridge Technologies Co AS 55