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This article introduces you how to understand the working process of NTP network time protocol, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Network time Protocol (NTP) is a time synchronization protocol defined by RFC 1305. It is used to synchronize time between distributed time servers and clients. NTP is isolated based on UDP and uses UDP port number 123.

The purpose of using NTP is to synchronize the clocks of all devices with the clocks on the network so that the clocks of all devices on the network are consistent so that devices can provide multiple applications based on a uniform time.

For local systems running NTP, it can accept synchronization from other clock sources, it can also be used as a clock source for synchronizing other clocks, and other devices can synchronize with each other.

How NTP works

The figure shows the basic operation of NTP. Device An and device B are connected through the network. They all have their own system clocks, and they need to synchronize their system clocks automatically through NTP. For ease of understanding, make the following assumptions:

Device A sends a NTP message to device B. The message leaves device A with a timestamp. The timestamp is 10:00:00 am (T1).

When this NTP message arrives at device B, device B adds its own timestamp. The timestamp is 11:00:01 am (T2).

When this NTP message leaves device B, device B adds its own timestamp and changes the timestamp to 11:00:02 (T3).

After device A receives the response message, device A's local time is 10:00:03 (T4).

At this point, device A has enough information to calculate two important parameters:

The round-trip delay for NTP packets is Delay = (T4-T1)-(T3-T2) = 2 seconds.

The time difference between device An and device B is offset = (T2-T1) + (T3-T4) / 2 = 1 hour.

In this way, device A can set its own clock based on this information and synchronize it with the clock of device B. The above is only a rough description of how NTP works. For more details, see RFC 1305.

NTP working mode

Based on client-server

In peer-to-peer mode

Use broadcast / Multicast send time.

Users can choose the appropriate working mode according to their own needs. When the IP address of the server or peer cannot be determined, and many devices need to be synchronized on the network, clock synchronization can be achieved by broadcast or multicast. In server and peer mode, the device starts from the specified server or peer.

On how to understand the NTP network time protocol working process to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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