[ntp:questions] Sync issue

Richard B. Gilbert rgilbert88 at comcast.net
Thu Sep 9 20:24:37 UTC 2010


Greene, Rick wrote:
> Cancel this...turns out, our network team had forgot to put a route in for this subnet, as it was a new subnet of our Class B IP range.
> 
> All my testing was from a different subnet of the same Class B, but of course the internet time servers are in different subnets entirely.
> 
> Rick
> 
> -----Original Message-----
> From: questions-bounces+rick.greene=ncogroup.com at lists.ntp.org [mailto:questions-bounces+rick.greene=ncogroup.com at lists.ntp.org] On Behalf Of Greene, Rick
> Sent: Wednesday, September 08, 2010 11:20 AM
> To: questions at lists.ntp.org
> Subject: Sync issue
> 
> I'm working on setting up our own "master clock" servers for our organization to get NTP time synchronization from.
> 
> The design calls for our master clock servers to get their time from several public NTP servers.
> 
> I initially set this up using Fedora Core 13 running as a VMware server inside our network, and was able to get it to sync up properly:
> 
>      [root at coruxdev etc]# ntpq -p
>           remote           refid      st t when poll reach   delay   offset  jitter
>      ==============================================================================
>      +time-a.nist.gov .ACTS.           1 u   44 1024  377   13.884    2.153   7.738
>      +clock.isc.org   .GPS.            1 u  815 1024  377   76.939   -6.417   0.171
>      *time-b.nist.gov .ACTS.           1 u  937 1024  377   12.309    0.460   4.231
> 
> I then took that same config and built it on our DMZ VMware environment, and in spite of being assured that our firewall is allowing UDP 123, I can't get time sync to work:
> 
>       [root at extux66 ~]# ntpq -p
>           remote           refid      st t when poll reach   delay   offset  jitter
>      ==============================================================================
>       time-a.nist.gov .INIT.          16 u    - 1024    0    0.000    0.000   0.000
>       clock.isc.org   .INIT.          16 u    - 1024    0    0.000    0.000   0.000
>       time-b.nist.gov .INIT.          16 u    - 1024    0    0.000    0.000   0.000
> 
> I've tried several different NTP troubleshooting documents found on the web, none have helped.  I've turned off iptables that was running on the local server, that didn't make a difference.
> 
> What could possibly be causing this?
> 

Well, it's not rocket science!  Your system is unable to get a response 
from *any* of the three servers you have configured.  I'm given to 
understand that NTP does NOT work very well, or at all, running in a 
virtual machine.  Try running in the *physical* rather than the virtual 
machine.  The virtual machines should then be able to get their time 
from the physical machine's clock.




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