Meaning
Networked devices achieve sub-microsecond synchronization through the precision time protocol by exchanging timed packets that account for transmission delays. This standard provides a method for a master clock to coordinate all other devices on a local network. It governs the timing of high frequency trading and telecommunications.
The protocol stops operating at the gateway to the wider internet where network jitter makes such precision impossible.
Synchronization Process
A sequence of messages records the exact nanosecond a packet leaves one port and arrives at another. By calculating the difference between these timestamps, the precision time protocol can subtract the time the packet spent traveling through the cable. This allows the slave clocks to adjust their frequency and phase to match the master clock perfectly.
The record of these adjustments shows the stability of the timing network over time and provides a historical log that can be examined to find intermittent faults in the synchronization chain.
Hardware Requirement
Achieving this level of accuracy requires specialized hardware that can stamp the time on a packet at the physical layer of the network. Ordinary software clocks are too slow because they are interrupted by the operating system. Because precision time protocol relies on this hardware support, it provides a much more reliable record than older methods like the network time protocol.
The cost of implementing this system is justified by the need for perfect coordination in high speed environments.
Network Stability
Any change in the network topology can introduce tiny variations in the time it takes for a signal to travel. The precision time protocol constantly monitors these changes and makes small corrections to keep all devices in sync. If the synchronization fails, the system logs an error that can be used to diagnose a faulty cable or a congested switch.
This evidence is necessary for maintaining the integrity of time sensitive data across a distributed system.
