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No NTP sync (between two switches 3750E)

Hallo,

I  have a great problem with our time synchronization. In our network  there are two switches Cisco 3750E (as coreswitch). One of them (first)  has a default ntp (server external) but the other switch cannot sync the  time from the first switch. The time from the second switch is after 15  minutes.

How can I sync this second switch with the first one? Which command can I use to sync a switch with another source?

#conf t

config#ntp server 192.168... ..

It does not work. The server is registered but not sync...

fyi:

#show ntp associations

         adress             ref clock   st   when   poll      reach

+~192.53.103.108      .PTB.       1    477    1024    377

* ~192.53.103.104      .PTB.       1    160    1024    377

show ntp.JPG

Thanks for your help!

Best regards,

Alex

4 REPLIES
New Member

Re: No NTP sync (between two switches 3750E)

Hi Alex,

You can configure the first switch as a master ntp server using "ntp master"

The second switch should be able to sync with the first switch after that.

http://www.cisco.com/en/US/docs/ios/12_1/configfun/configuration/guide/fcd303.html#wp1001170

Tim

Hall of Fame Super Silver

Re: No NTP sync (between two switches 3750E)

Alex

I am not understanding your question. It asks about problems in achieving sync but the command output that you shows clearly says that the device has successfully established sync. Where is the problem?

HTH

Rick

New Member

Re: No NTP sync (between two switches 3750E)

Hello Rick,

its correct that the sync is successfully. But we have a false time. If I use the "#show ntp status" command I get following information:

Clock is synchronized, stratum 2, reference is 192.53.103.104
nominal freq is 119.2092 Hz, actual freq is 119.2160 Hz, precision is 2**18
reference time is D02B6219.F44C77D3 (14:01:29.954 mest Fri Sep 3 2010)
clock offset is -30.7319 msec, root delay is 80.57 msec
root dispersion is 158.34 msec, peer dispersion is 132.11 msec

But our real time clock is 14:15. (15min after)

What can I do? We need the correct time urgently.

Best regards,

Alex

Hall of Fame Super Silver

Re: No NTP sync (between two switches 3750E)

Alex

I have never known one of the sources of NTP on the Internet to be off by 15 minutes and am very puzzled what could be causing your symptoms. Perhaps if you were to post the configuration of the switch we might find something.

The only other suggestion that I have at this point might be to try using a different NTP source in the Internet and see if you get different results.

HTH

Rick

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