[ntp:questions] NTP.ORG MEINBERG KEEP TIME ACCURATE to 10MS

unruh unruh at invalid.ca
Thu Nov 15 06:36:49 UTC 2012


On 2012-11-14, gbusenberg at yahoo.com <gbusenberg at yahoo.com> wrote:
> They HP DL 380 G7 Servers.  Sorry for the typo.  No virtual machines are being used.  Each Windows 2008 Server has dedicated hardware and is almost idle in terms of load. Yesterday after making the changes of getting rid of the tinker and server 127.127.1.0 & fudge 127.127.1.0 everything seemed better however after it ran for about 18 hours, I am back to about 250ms offsets in ntpq -p.
>
> I will try the suggestions that Charles made and then if that doesn't work, I will try the latest binaries that David suggested.
>
> server 10.1.126.204 iburst minpoll 5 maxpoll 5
> broadcastclient 
> broadcastdelay 0.000800  ## in seconds 
>
>
> I want to give some more detals on my setup just to make sure there is nothing important that I have not shared:
>
> My small network of 8 Windows 2008 Servers & Windows 7 PCs are all on the same 1gbps LAN.  10.1.126.204 is one of my servers and syncs time with 20.200.0.1.  ntpq -p is shown below for 10.1.126.204
>
>
>      remote           refid      st t when poll reach   delay   offset  jitter
>==============================================================================
> *20.200.0.1      132.163.4.101    2 u  407  512  377    0.051  119.693  37.748
>
> 20.200.0.1 only supports NTP Version 3.  On 10.1.126.204, I have my ntp.conf file set as follows
>
> driftfile "C:\Program Files (x86)\NTP\etc\ntp.drift"
> server 20.200.0.1 version 3 iburst minpoll 4
>
> I can understand that I would have a hard time keeping good NTP time with 20.200.0.1 since this server doesn't support NTPV4.  The thing I don't understand is why all of my other servers that get their NTP time from 10.1.126.204 using NTPV4 are unable to keep a low offset after the NTP Service has been running for about a day.

NTPv4 or V3 are essentially the same as far as timekeeping are
concerned. That certainly should not be where the problem is.  Wht is
20.200.0.1? (ie what kind of machine, what OS. Where does it get its
time from-- well I guess 132.163.4.101)

Anyway, set up logging of the peerstats, and plot the offset as a
function of time, and see if it really is jumping around as badly as the
ntpq seems to be saying it is. Certainly with a delay of .051 ms you should
not be getting 200ms of offset.  

Also plot the offset and delay of 20.200.0.1 to see if IT is jumping
around in time ( you cannot get better time than your server delivers).
 
>
> Below ntpq -p from my 10.1.126.202 server which gets time from 10.1.126.204.  I see there is a lot of Jitter.  Is the offset of 259ms. 


>
>      remote           refid      st t when poll reach   delay   offset  jitter
>==============================================================================
> *10.1.126.204  20.200.0.1       3 u 1006 1024   77    0.043  -259.69 165.850
>
> driftfile "C:\Program Files (x86)\NTP\etc\ntp.drift"
> server 10.1.126.204 iburst minpoll 4
>
> My machines are in a Windows 2008 Domain.  There are no firewalls and all firewalls on the Windows Servers is disabled.  I have verified on all machines that the Windows Time Service is disabled so I am only using the "Network Time Protocol Daemon".
>
> I went through the install guide for windows at:
>
> http://www.satsignal.eu/ntp/setup.html
>
> Greate guide.  Wish the Meinberg site had a link to this (Or maybe it doesn and I just missed it).  Everything looks good on my end except I left the default of installing in Program Files as opposed to C:\Tools which I don't think is my issue.  I will try the steps to upgrade the binaries to 4.2.7p285 in the Guide. Also, I checked Event Viewer on a couple of servers and there are no errors for NTP.



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