3com WX3000 Manuel D’Utilisation

 

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In network management, the analysis of the log information and debugging information collected 

from different devices is meaningful and valid only when network devices that generate the 

information adopts the same time. 

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The billing system requires that the clocks of all network devices be consistent. 

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Some functions, such as restarting all network devices in a network simultaneously require that 

they adopt the same time. 

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When multiple systems cooperate to handle a rather complex transaction, they must adopt the 

same time to ensure a correct execution order. 

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To perform incremental backup operations between a backup server and a host, you must make 

sure they adopt the same time. 

NTP has the following advantages: 

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Defining the accuracy of clocks by stratum to synchronize the clocks of all devices in a network 

quickly 

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Supporting access control (See 

) and MD5 encrypted 

authentication (See 

) 

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Sending protocol packets in unicast, multicast, or broadcast mode 

 

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The clock stratum determines the accuracy, which ranges from 1 to 16. The stratum of a reference 

clock ranges from 1 to 15. The clock accuracy decreases as the stratum number increases. A 

stratum 16 clock is in the unsynchronized state and cannot serve as a reference clock. 

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The local clock of the device cannot be set as a reference clock. It can serve as a reference clock 

source to synchronize the clock of other devices only after it is synchronized. 

 

 shows the implementation principle of NTP. 

Device A is connected to Device B through Ethernet ports. Both having their own system clocks, they 

need to synchronize the clocks of each other through NTP. To help you to understand the 

implementation principle, we suppose that: 

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Before the system clocks of Device A and Device B are synchronized, the clock of Device A is set 

to 10:00:00 am, and the clock of Device B is set to 11:00:00 am. 

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Device B serves as the NTP server, that is, the clock of Device A will be synchronized to that of 

Device B. 

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It takes one second to transfer an NTP message from Device A to Device B or from Device B to 

Device A.