NTP Status: Clock is unsynchronized

[David Draper]

I have been having issues with a 3750X Stack that is not synchronizing with our NTP server. I have tried adding and removing the NTP server but it does not help. We are running Version 15.2(1)E. Any suggestions would be great! Thanks!

[daniel.dib]

Can you post show ntp status and sh ntp associations detail to begin with. Which server are you trying to sync with, internal or external? No ACLs or firewalls in the way that could possibly block it? No authentication for NTP?

Daniel Dib
CCIE #37149

[David Draper]

Daniel,
Thanks for the quick reply.  Here is the “sh status” and “sh ntp associations”
Sh ntp status

Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 119.2092 Hz, actual freq is 119.2092 Hz, precision is 2**19
ntp uptime is 26320700 (1/100 of seconds), resolution is 8403
reference time is 00000000.00000000 (18:00:00.000 CST Thu Dec 31 1899)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.16 msec, peer dispersion is 0.00 msec
loopfilter state is 'FSET' (Drift set from file), drift is 0.000000000 s/s
system poll interval is 64, never updated.

sh ntp associations

  address         ref clock       st   when   poll reach  delay  offset   disp
~x.x.x.x    .LOCL.           1     40     64   377  2.409 2723270 16.508
~x.x.x.x     x.x.x.x     2      5     64   377  2.298 2723270 16.528
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

We are using our internal Windows Domain Controller as an NTP source.  I have multiple 3750 stacks looking at our DCs without an issue.  Thanks!

[Leo Laohoo]

We are using our internal Windows Domain Controller as an NTP source.

This is interesting because MS's implementation of S/NTP is not of standard.

Can I ask what IOS are rest of the stack (working NTP with your Domain Controller) running on?

Not a lot of people are running 15.1(2)E.

[David Draper]

Leo,

  Thanks for the response!  We are running Version 12.2(55)SE3 on the other Stacks. 

[Leo Laohoo]

If you downgrade your 3750X to 12.2(55)SE8, would it work?

[Jeff Van Houten]

Post all the ntp commands you have configured. The local clock should not be stratum 1.

Sent from Cisco Technical Support iPad App

[David Draper]

Jeff, Leo,

  The only ntp commands that I have on the 3750 Stack is:

     ntp server 10.x.x.x (primary domain controller)

     ntp server 10.x.x.x (secondary domain controller)

     I can downgrade to 12.5(55)SE8 to test if you like.

     Thanks for the help guys!

[Jeff Van Houten · Accepted solution]

Have you set the time zone on the stack yet? Also have you set the time on the switch to something close to the time on the DCs?

Sent from Cisco Technical Support iPad App

[umesh.chowdhary]

Please have a look at below link

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note0918

[Caughtflying]

Thx Jeff

[Leo Laohoo · Accepted solution]

I can downgrade to 12.5(55)SE8 to test if you like.

There are two ways to this and either one can suit you.

1.  You can use your other switches to synch your NTP.

2.  You can downgrade and test.  But if the test fails, then you can use option 1.

[David Draper]

Jeff, Leo,

OK, here is something interesting..... I can get NTP to sync up with our older 2008 internal Doman Controllers. We are in the process of upgrading our DCs to 2012. We have two 2008 DCs that are about to be decommissioned and three 2012 DCs that are our primary DCs. I cannot get this 3750 stack to sync up with the 2012 DCs but I can get it to sync with out 2008 DCs. I have four 3750 stacks that are working with our new 2012 DCs but they are running IOS 12.2. Thanks!

[David Draper]

Jeff, Leo,

            So it looks like the other 3750 stacks had issues with the new 2012 DCs as well. We looked at the external NTP source and redirected it to a new source. After the NTP redirect and about 15 minutes all of our 3750 Stacks including the Stack on 15.2 have synced up correctly. Thanks again for all your help!

[Leo Laohoo]

Thanks for taking the time to rate our posts, David.