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Network Time Protocol or Simple Network Time Protocol

By: David Evans

Network Time Protocol (NTP) is one of the oldest Internet protocols currently in use. NTP was developed to disseminate accurate time to clients around a computer network. Simple Network Time Protocol (SNTP) is a much less complex implementation of NTP. SNTP lacks many complex synchronisation algorithms used by NTP which makes it ideal for implementation on small computers.

This article describes the differences between NTP and SNTP. The article also discusses when SNTP can be safely used in place of the full-blown NTP protocol. The article also descibes the differences between a NTP server and a SNTP server.

NTP protocol packets transferred between a NTP server and client are identical to SNTP packets. Each field in a NTP packet of information has a corresponding field in a SNTP packet. NTP protocol packets are entirely interchangeable with SNTP protocol packets. Indeed a NTP server cannot differentiate a request for time originating from a NTP client or SNTP client.

The difference between the NTP and SNTP protocols is contained within the sophisticated routines used to implement the protocols. NTP has sophisticated routines designed to monitor multiple time references and decide which is the optimal reference. NTP constantly monitors multiple time references for jitter and offset and decides which is the best one to synchronise. NTP corrects time by slewing the system clock. The host's system clock is accelerated or decelerated to slowly bring it into line with an accurate external time reference. Large stepped time adjustments are avoided. NTP has complex synchronisation algorithms that calibrate the system clock to match the frequency of an accurate reference clock.

SNTP is a simplified sub-set of the algorithms used by the NTP protocol. SNTP steps the host computers system time rather than slowly slewing it towards the correct time. Adjusting the system time in steps can cause time critical applications problems. SNTP also lacks the functionality to monitor multiple NTP server reference clocks and decide on the optimal source of time. Instead it utilises a list of references and in the event of failure of a reference it moves on to the next.

SNTP is ideal for synchronising computers at the leaves of a network. It is ideally suited to less powerful processors, such as micro-controllers and embedded systems, which do not require the accuracy of NTP. The complex algorithms of NTP may not be practically implemented on small computers. NTP is ideal for use in dedicated NTP server systems and synchronising large networks of computers. Here, time may be critical and the added complexity of NTP will help maintain accurate synchronisation.

Article Source: http://articleblender.com

Dave Evans is an author with a technical background in NTP Server solutions and implementation. Dave provides a free-lance technical authoring service to a number of NTP server manufacturers. Dave has also provided configuration, installation and support services to the computer timing industry. Click here to find out more about ntp server systems.

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