NTP (Network Time Protocol) Overview
NTP time servers for synchronization accuracy
Network Time Protocol, or NTP as it is more commonly known, provides a mechanism to synchronize the time of computing devices and other network infrastructure. The protocol was originally developed for the Linux operating system by Dr D Mills, University of Delaware. For over two decades, the NTP time synchronization provided critical devices on the Internet makes it one of the oldest protocols still in continuous operation. This article gives a brief overview of NTP and some of the technical terms used in the timing computer.
NTP was originally developed to solve the requirement of time synchronization of critical processes across the Internet. The Network Time Protocol main platform is the Linux operating system. NTP is provided under the GNU public license, but it has also been successfully ported to the Windows operating system. NTP is widely used on Linux as most of the algorithms necessary to provide precise time are integrated into the kernel.
NTP uses UDP (User Data-gram Protocol) over TCP / IP. NTP messages are communicated using UDP port 23, which is reserved for the exclusive use of NTP traffic. The protocol is essentially composed of a number of areas, which statelock offset, roundtrip delay and dispersion relative to a source of accurate time. The information stored in each packet to allow an NTP client time to accurately synchronize the time with an NTP server.
NTP is a protocol that works structured hierarchically. At the top of the tree, a primary time reference is known as a time server stratum 1. The servers that synchronize with a stratum 1 server are known as stratum 2 servers and so on each level of the hierarchy. As the stratum increases, so generally reduces the accuracy.
For a number of years NTP has been enhanced to work with a plethora of hardware devices precision clock or clock reference. NTP reference clocks are available for the GPS hardware and a lot of time for the National Radio and frequency standards such as MSF, WWVB and DCF-77. A number of third party hardware manufacturers have installed the synchronization precision crystals in their reference clocks to provide precise timing reference backup.
A spin-off from NTP or SNTP is Simple Network Time Protocol, which is basically as the name suggests, a simplified version of NTP. SNTP is generally used in small devices such as low computational power micro-controllers. It enables low power devices can synchronize the time of NTP servers on a network.
To summarize, NTP is a longstanding and widely used protocol for time synchronization between time-critical processes. It has a hierarchical structure that allows easy synchronization of a large number of network time clients. For applications requiring critical sync, NTP provides a solution de-facto standard.
Editors note: Arbiter Systems provides a series of GPS based, precision time clocks featuring NTP technology. Click here to review the full product list.« Back to Advancing the Technology Index