Time Synchronization Protocols

Time synchronization protocols define standards for the combination of the timing request and the time code. The protocol must be able to read a server clock, transmit the reading to one or more clients, and adjust each client clock as required.

The time synchronization protocol along with factors such as clock frequency drift, clock resolution, and network delay determines how closely the server clock and the client clock are synchronized.

Network Time Protocol (NTP)

NTP, specified in RFC 1305, is a protocol for synchronizing computer clocks across a network to standard time. The NTP client software runs continuously as a background task that periodically receives updates from one or more servers. The client software ignores responses from servers that appear to be sending the wrong time and averages the results from those that appear to be correct.

With the appropriate hardware, NTP is capable of achieving synchronization to within microseconds, depending on the synchronization source and the network paths.

NTP synchronization is part of a software package that includes a full suite of NTP options and algorithms, which are relatively complex, real-time applications. The sheer size and complexity of the NTP suite is not appropriate for many environments that do not have stringent accuracy requirements.

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Simple Network Time Protocol (SNTP)

SNTP is a basic version of NTP. It provides a simplified access strategy for servers and clients that do not require the degree of accuracy of the NTP protocol. SNTP is meant to operate in a dedicated server configuration, that is, one in which the server provides only one function. With careful design and control of the various latencies that are typical in such network design, it is possible to deliver time accurate to the order of milliseconds.

Related Product

Express Timesync is an ideal solution for keeping the computer clock accurate. It supports SNTP, TIME, SOCKS 4, SOCKS 4A and SOCK 5 protocols. The program provides a wide range of options for managing your computer clock time and keeping it accurate.

Express Timesync
Express Timesync is an ideal solution for keeping the computer clock accurate. It provides a wide range of options for managing your computer clock time and keeping it accurate.

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Because the network packet formats of both protocols are identical, the two are interoperable. The main difference between the two is that SNTP does not have the error management and complex filtering systems that NTP provides. The SNTP protocol allows room for error and might not be suitable for some corporations such as those in the financial industry that have very strict accuracy requirements.

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Time Protocol (TIME)

TIME protocol, specified in RFC868, provides a site-independent, machine readable date and time. The Time service sends back to the originating source the time in seconds since midnight on January first 1900.

Since the TIME protocol sends timestamps in seconds, it can provide only ą1 second accuracy and should be used only when it is impossible to use SNTP.

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Daytime Protocol (DAYTIME)

DAYTIME protocol is widely used by small computers running MS-DOS and similar operating systems. The server responds to requests in either tcp/ip or udp/ip formats. DAYTIME timestamps are sent using standard ASCII character strings.

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