Why Is Network Time Synchronisation Important?

PC's maintain time using internal hardware clock chips. In order to reduce costs, these components are relatively low-cost devices, notoriously prone to drift. Therefore, the system time on a collection of networked computers can drift away from each other at different rates. After a relatively short period of time, large differences between the system times of each computer will be unavoidable. Unsynchronised time on computers on a network can lead to many problems. This article discusses the importance of computer network time synchronisation and of having an accurate network time reference in an organisation.

Poor time synchronisation on a computer network can lead to a number of problems. For instance, in a transaction-processing application, transactions generated from various PC's on the same network may have irregular time-stamps. This may lead to incorrect processing of ordered transactions. Additionally, unsynchronised computers may be vulnerable to fraud, particularly in situations where transaction time is an important issue. Problems can also arise with shared network files, if computers with unsynchronised system times are using the same resource, file updates may not be ordered correctly.

Network time servers receive precise timing information from an external time source, such as GPS or radio, and provide an accurate time reference to network time clients. In this manner, all computers and network infrastructure can be synchronised to the same precise time.

Time servers generally utilise the Network Time Protocol, or NTP, which is a standard protocol for distributing time around a network. NTP is a UDP based protocol over TCP/IP, which is a standard network protocol that most networks utilise, including the Internet. A number of external time references are available that time servers can utilise, such as GPS and regional radio frequency transmissions. The Global Positioning System (GPS) is a free to air service that provides a highly accurate source of time. However, GPS antennas require a good view of the sky in order to obtain timing information, which can increase installation costs. Regional radio time and frequency transmissions include: MSF transmitted from Anthorn in Cumbria (UK) with coverage of most of the British Isles and North-Western Europe; DCF-77 transmitted from Frankfurt (Germany) with coverage of much of Central Europe; WWVB transmitted from Colorado (US) with coverage of much of the US and Canada. Other regional radio time references include: TDF (France); CHU (Canada); JJY (Japan) and HBG (Switzerland).

There are many Internet based NTP servers available that can be utilised for network time synchronisation. However, utilising an Internet time reference can have a number of issues. Firstly, the time server is located outside of your firewall, so a port must be left open in order to access the server. This obviously has security implications. Also, accuracy, reliability and provision of service may be erratic.

A local dedicated time server overcomes all of the issues associated with Internet based references. A local server resides inside your firewall and so requires no external access, overcoming any security issues. Also, a local time server will have improved accuracy due to consistent network paths between clients and server. There should be no provision of service issues, since the time server is owned by the organisation where it is installed.

To summarise, network time synchronisation is an important factor in modern computer network installations. Internet based time servers may provide a low-cost solution to network synchronisation, but there are accuracy, security and provision of service issues that arise with their use. Dedicated network time servers overcome the security and accuracy issues associated with internet based services by providing a secure, accurate and reliable source of time inside your firewall.

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About the Author:
Dave Evans is an experienced technical author who is involved in the development of Radio and GPS based NTP time server synchronization solutions that ensure accurate time on computer networks. Click here, for more information about Radio and GPS NTP Server solutions.