Troubleshooting guide

3. Troubleshooting Functional Failures During Operation
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3.18 NTP communication failures
3.18.1 The Switch cannot be synchronized by using NTP
If the system clock cannot be synchronized by NTP, isolate the cause of the problem according to
the failure analysis method described in the following table.
Table 3-75: NTP failure analysis method
No. Items to check and commands Action
1Use the
show clock command to make
sure the time zone is set.
If the time zone is set in the information displayed by the command, go
to No. 2.
If the time zone is not set in the information displayed by the command,
set the time zone.
2 Check the time difference between the
Switch and the NTP server.
If the time difference between the Switch and the NTP server is less than
1000 seconds, go to No. 3.
If the time difference between the Switch and the NTP server is 1000
seconds or more, use the
set clock command to match the system clock
of the Switch with the NTP server.
3 Check communication with the NTP
server via IPv4.
Use the
ping command to check whether communication is possible via
IPv4 between the NTP server and the Switch.
Make sure that there is no setting for discarding any packets at the UDP
port number 123 in the settings of the NTP server or the Switch.