The Precision Time Protocol (PTP) provides clock accuracy for networked devices, allowing clocks to be synchronized locally in increments of less than a microsecond. PTP uses a master-slave hierarchy similar to that used by NTP. The master clock provides the most precise time, and slave devices use its signal to synchronize their clocks.

The master clock sends a sync request, called an announce message by the IEEE 1588-2008 standard, at a regular interval. The slave clock responds with a time-stamped delay request message in order to measure and compensate for packet delays between the devices. The slave then receives a message from the master specifying the time of the delay message and allows the slave to calculate final values for clock synchronization. The time maintains synchronization by regularly exchanging PTP packets between master and slave.