The Precision Time Protocol (PTP) is a time-transfer protocol defined in the IEEE 1588 – 2002 standard that allows precise synchronization of networks (e.g., Ethernet). Accuracy within the nanosecond range can be achieved with this protocol when using hardware generated timestamps, although the protocol itself has no quality requirement.
The Institute of Embedded Systems (InES) of the University of Winterthur is addressing the practical implementation and application of PTP.
IEEE 1588 is a key technology in the LXI Standard for Test and Measurement communication and control.
"IEEE 1588 is designed to fill a niche not well served by either of the two dominant protocols, NTP and GPS. IEEE 1588 is designed for local systems requiring very high accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible."
Source: Wikipedia (http://en.wikipedia.org/wiki/IEEE_1588)