What is a grandmaster clock?
When using a precision timing protocol (PTP) timing network, the grandmaster clock is the main distributor of time in a multi-clock network, sending time downstream to other master clocks.
Sometimes more than one clock could feasibly be the grandmaster. To decide which clock becomes the master, the clocks automatically use the Best Master Clock Algorithm (BMCA). This determines which clock is the better or most accurate source of time for the network.
Used to: provide the best source of time when several are available, and provide time to other clocks on the network (PTP only)