[ntp:questions] Making a clock tell the wrong time?

Steve Kostecke kostecke at ntp.org
Mon Mar 9 17:49:15 UTC 2009


On 2009-03-09, Mike K Smith <mks-usenet at dsl.pipex.com> wrote:

> For testing purposes I want to configure an NTP server to run with a
> small but known offset. I would like to test at the following offset
> values 25, 90, 180, 350 and 2500ms.

What is this test intended to prove?

> I tried the naive approach first - I synced a Linux PC to a stratum 1
> server and once it was stable I reconfigured NTP to run the local
> clock at stratum 0

Setting the Undiscplined Local Clock to stratum 0 instead of the default
stratum 5 does not make it a better "clock". What are you trying to
accomplish with this?

> with a fudge line to set the time1 parameter to 90ms.
>
> The server showed a 90ms offset after the first poll of the local
> clock, but within a few poll cycles it had discarded the offset.

That's because ntpd disciplined the clock to amortize that offset.

Once this has happened, the clock is now operating at the 90ms offset.

Isn't this what you wanted?

-- 
Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/




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