Merit Network Time Protocol (NTP) Services

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Network Time Protocol (NTP) Services

For time-sensitive, mission-critical computer applications, NTP services are essential in maintaining accurate timekeeping across a network. Merit is now offering Stratum 1 NTP services as a value-added feature to our Members.


The standard timescale used by most nations of the world is Coordinated Universal Time (UTC), which is based on the Earth's rotation about its axis, and the Gregorian Calendar, which is based on the Earth's rotation about the Sun. The UTC timescale is coordinated with International Atomic Time (TAI) by inserting leap seconds at intervals of about 18 months. UTC time is disseminated via radio and satellite navigation systems, telephone modems, portable clocks and other means.

For reasons of cost and convenience, it is not possible to equip every computer with an UTC receiver. However, it is possible to equip some number of computers acting as primary time servers to synchronize a much larger number of secondary servers and clients connected by a common network. This requires a distributed network clock synchronization protocol that can read a server clock, transmit the reading to one or more clients and adjust each client clock as required. One major protocol is Network Time Protocol (NTP).

The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. NTP uses UDP port 123 as its transport layer. It is designed particularly to resist the effects of variable latency.

NTP uses Marzullo's algorithm with the UTC time scale, including support for features such as leap seconds. NTPv4 can usually maintain time to within 10 milliseconds (1/100 s) over the public Internet, and can achieve accuracies of 200 microseconds (1/5000 s) or better in local area networks under ideal conditions.

NTP uses a hierarchical system of "clock strata", where stratum 1 systems synchronize to an accurate external clock such as a GPS clock (usually through a Pulse per second signal) or other radio clock. NTP stratum 2 systems derive their time from one or more stratum 1 systems, and so on.

The synchronization protocol supports a large and varied number of communities. Each community is organized as a subnet, with the primary servers at the root and secondary servers and clients at increasing hop count, or stratum level, from the data source.

NTP Server Drawing

Reliability & Accuracy

Merit's new NTP services utilize a Spectracom Netclock/GPS time server that provides Stratum 1 server functionality, which is essential for sophisticated end-to-end network measurement and split-second timing for mission critical systems. The Spectracom NetClock/GPS time server automatically tracks up to twelve satellites simultaneously, and provides extremely accurate timing by synchronizing to the satellites' atomic clocks.

Have questions about Merit Network Time Protocol (NTP) Services? Contact a Member Relations Manager at or 734-527-5700.

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