[ntp:questions] Client taking a long time to sync after clock changed

Merit Wilkinson meritw at gmail.com
Wed Aug 22 15:25:14 UTC 2007


Well, my original message hasn't made it through moderation yet, but I
found a solution to my 'problem'.  I used "tinker stepout" to decrease
the required time between clock steps.  By setting it very low (10
seconds) I can get the sync time down to a couple of minutes, which
should be fine.  I suspect this is one of those Bad Ideas, but it
seems to be working for me.

I also changed burst to iburst since it doesn't seem to have any
effect other than increasing network traffic.  The client re-syncs
pretty quickly with iburst since the server goes unreachable then
reachable after the clock change.

One more question: is there a way to change the time it takes to
declare a server unreachable?  In other words, can I declare it
unreachable after just a couple of missed polls instead of 8?  These
machines are all on a local network with not much traffic, so in
reality if they miss more than one poll the server is probably really
gone, or has stepped, or something.

Thanks

On 8/21/07, Merit Wilkinson <meritw at gmail.com> wrote:
> Hello all,
> We have a small isolated NTP subnet with two stratum 1 servers.  As
> part of a test we reset the clock on one workstation backwards two
> minutes.  ntpq immediately showed the offset (and claimed it was still
> synchronized to one of the servers) but it took about 14 minutes until
> it was suddenly corrected with one step.
> We're using ntp 4.1 built for win32.  Here is the clients ntp.conf:
> --
> disable auth
> tinker panic 0
>
> server sn-a maxpoll 4 minpoll 4 burst
> server sn-b maxpoll 4 minpoll 4 burst
> --
> I added the maxpoll and burst options in an attempt to get this time
> down.  It was similar before I changed it.
>
> Does this seem normal?  Is there some way I can reduce this time?
>
> Note, I realize this isn't a particularly valid test, hopefully no one
> is going around changing the system time (or has permission to do so)
> but it got written into the test procedures...
>
> Thanks
>



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