What is a Time Server?
What is a Time Server?
A time server is a computer that reads the actual time from a reference clock and distributes it to clients using a computer network. Time servers can use GPS or atomic clocks as a time reference and can be dedicated devices or existing network servers equipped with additional software.
Network Time Protocol (NTP) / Precision Time Protocol (PTP)
Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over variable-latency data networks.
NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses a modified version of Marzullo’s algorithm—the intersection algorithm—to select accurate time servers and is designed to mitigate the effects of variable network latency.
NTP can usually maintain time to within tens of milliseconds over the public Internet and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric routes and network congestion can cause errors of 100 ms or more.
The Simple Network Time Protocol (SNTP) was developed as a simplified version of NTP, eliminating the need for long-term state storage. SNTPv4 is a version that includes features from NTPv4 and was merged into the main NTPv4 standard in 2010. Although SNTP is interoperable with NTP, it provides less accurate time synchronization due to its simplified algorithms.
Network Time Protocol (NTP) and Simple Network Time Protocol (SNTP) are popular methods for synchronizing clocks on a Local Area Network (LAN) with millisecond-range precision. However, many industrial time synchronization applications require greater accuracy. Wherever processes—such as automation and control systems, measurement and automated test systems, power generation, transmission and distribution systems, and telecommunications—demand this level of precision, Precision Time Protocol (PTP) is the appropriate solution.
As the needs of network design become more prevalent across many industries, the demand for accurate time is deepening.
When a network contains a large number of IEDs (Intelligent Electronic Devices) with their own internal clocks, coordinating them becomes difficult; this is where centralized time servers become essential. A highly accurate precision timing source in a network can maintain a consistent timebase and typically synchronize all IEDs within 100ns. The applications of accurate time are diverse, especially in scenarios where digital instructions must be executed at precise moments or where data is transferred at high speeds. Installations also typically include event logging.
Knowing exactly when an event occurred is critical in many industries where fault tracing is necessary. The speed of electricity makes this especially important for the power sector; precise timing is also used for phase measurement, multi-rate billing accuracy, locating faults on transmission lines, relay testing, and more. In some cases, a network needs to be synchronized over several miles. In such instances, GNSS-based timing is often the only cost-effective option.
