Spectracom - Essential Ingenuity

PTP Accuracy

Question

What is the accuracy of PTP?

Answer

The accuracy of any PTP implementation is defined by the network between the Master and Slave.  Any Packet Delay Variation (PDV) introduced by the network will affect the ultimate accuracy.  Even a single router will introduce some PDV depending on how it processes its packets.  The “no hop” configuration is a Master connected to a Slave via direct crossover cable.  With our PTP equipment, you would get ~10s nanoseconds accuracy with a "no hop" configuration.

Each network router hop will decrease the accuracy. How much will depend on the traffic load and the router itself.  There are PTP enabled routers that adhere to the IEEE-1588v2 protocol and provide the “Transparent Clock” function.  With this feature, the router modifies a timestamp field in the PTP packets it processes to compensate for any variable resident delay it introduces.  This greatly reduces the PDV factor.  There are not many of these types of routers available today, but more and more are adding this functionality.

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