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The hosts synchronize the time with both NTP and PTP. This is done by the timemaster service during the network configuration section. (see Network TO REMOVED section).
Three tools are used:

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• Load the kernel module ptp_kvm, either automatically at boot or manually.
  This will create a ptp device in /dev/. To determine which device is the one created by ptp_kvm, simply check that the file /sys/class/ptp/ptp*/clock_name does indeed say "KVM virtual PTP". 
  In this example, our ptp_kvm device is ptp0.

• Synchronize the system clock with the PTP clock.

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