Based on the principle of SNTP protocol, this paper mainly describes the functional requirements and usage notes of SNTP server in the application of time synchronization, and helps users to select and use SNTP server.

The SNTP protocol is a subset of the NTP protocol. It is the client of the simple network time protocol, which can be used to query or modify the time and local time difference of the NTP server.

SNTP server as a time synchronization server is based on NTP protocol to achieve the goal of time unification. NTP is a Internet standard protocol for synchronizing network devices and server clocks. It can estimate the round-trip delay on the network, and can independently estimate the clock bias of the computer itself, so as to achieve uniform and standard time on Internet, provide high precise time synchronization service, and achieve the goal of high precision computer timing.

The SNTP server that our company produces now is based on the standard NTP protocol, configuring the standard NTP time service core card to realize the time synchronization function. Its NTP time service core card is the only core time service module currently available in the market. It is compatible with NTP standard protocol, SNTP protocol and other subset protocols. It also includes 10/100M and 10/100/1000M adaptive NTP time service core card.

At present, the SNTP servers that satisfy the market application have various types of equipment. The most commonly used time correction devices such as SYN2101/2102/2104/2131/2132/2134/2136/2138/4505 and other timing synchronization devices on the market are simple functions:

As shown in the figure, the most commonly used SNTP server is mainly based on the receiving satellite time model, and is connected to the NTP network through the switch to synchronize the computer equipment in the equipment.

The synchronous server based on SNTP protocol is usually based on computer time service. Its main application is because each computer has its own clock, but once they are running, there is another problem: how to solve the accumulated errors of each computer clock running on each other.

SNTP provides accurate time, first of all, there must be an accurate time source. This time should be standard time. In order to prevent malicious damage to time servers, NTP uses the Authentication mechanism to check whether the time information is really from the claimed server and check the return path of the data to provide a protection mechanism against interference. With the increasing complexity of network topology, the clock synchronization of devices in the whole network will become very important. The emergence of SNTP is to solve the synchronization problem of the clock in the computer network.

The SNTP time synchronization server receives the satellite time, realizes the time synchronization synchronization function through the NTP transmission. When synchronizing with the lower level computer, the simplest method is to adjust the system's "date and time attribute". Just double-click the time of the lower right corner of the system, enter the NTP time server IP address in the "Internet time" address bar, click "update immediately", so that the system clock synchronization can be realized quickly and accurately.

If the satellite is out of lock, the SNTP time synchronization server will maintain its precision time by its own clock, and send the request to the upper level server on its own in the appropriate time period. What needs to be explained is that the most critical factor affecting the accuracy of SNTP protocol is the randomness of the network delay, which leads to the inaccuracy of clock delay calculation, and also depends on the accuracy of the local clock hardware.

The above is a description of the application principle and practical application of SNTP server to achieve computer time synchronization, for reference only.

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