Advantages of ntp, How ntp works – H3C Technologies H3C S7500E Series Switches User Manual
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For incremental backup between a backup server and clients, timekeeping must be
synchronized between the backup server and all the clients.
Advantages of NTP
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NTP uses a stratum to describe the clock precision, and is able to synchronize time among
all devices within the network.
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NTP supports access control and MD5 authentication.
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NTP can unicast, multicast or broadcast protocol messages.
How NTP Works
shows the basic workflow of NTP. Device A and Device B are interconnected over a
network. They have their own independent system clocks, which need to be automatically
synchronized through NTP. For an easy understanding, we assume that:
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Prior to system clock synchronization between Device A and Device B, the clock of Device
A is set to 10:00:00 am while that of Device B is set to 11:00:00 am.
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Device B is used as the NTP time server, namely, Device A synchronizes its clock to that of
Device B.
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It takes 1 second for an NTP message to travel from one device to the other.
Figure 3-1 Basic work flow of NTP
IP network
IP network
IP network
IP network
Device B
Device A
Device B
Device A
Device B
Device A
Device B
Device A
10:00:00 am
11:00:01 am
10:00:00 am
NTP message
10:00:00 am
11:00:01 am
11:00:02 am
NTP message
NTP message
NTP message received at 10:00:03 am
1.
3.
2.
4.
The process of system clock synchronization is as follows:
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Device A sends Device B an NTP message, which is timestamped when it leaves Device A.
The time stamp is 10:00:00 am (T1).