Re: [chrony-users] Poor synchronization to local NTP server

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

On Tue, 16 Mar 2021, Ryan Govostes wrote:

> [CAUTION: Non-UBC Email]
>
> I am running ntpd on a local server. That server syncs its clock to pool.ntp.org.
>
> Now I want another device, running chrony, to sync its clock to the local server, so I configured chrony with `server asdfasdfa iburst`. For comparison I also added `server time.nist.gov iburst`.
>
> I’m not sure I’m interpreting the output of chronyc correctly but it seems that it is getting a much better fix to the remote NIST server than to the local server which is on the same subnet and responds to ping in < 0.5 ms.

That does not matter. What is more important is that asdfasdfa is stratum 4
and probably has a pretty bad root dispersion. The length of the hop is not
the most important thing. You could have a stable long hop, or an unstable
short hop, and the long hop would deliver better time. But in your case,
asdfasdfa has at least 3 hops, each of which could be unstable.

> MS Name/IP address         Stratum Poll Reach LastRx Last sample
> ===============================================================================
> ^- asdfasdfa                     4   6     7     2    +39ms[ -669us] +/-  109ms
> ^* time-d-b.nist.gov             1   6     7     2    -16us[  -40ms] +/-   27ms
>
> Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
> ==============================================================================
> asdfasdfa                   8   4   265     -1.772      4.203    +39ms   191us
> time-d-b.nist.gov           8   6   265     -2.494      9.770    -61us   442us
>
> What could I start looking into to diagnose the issue? Is it likely to be chrony or the ntp server at fault?

Neither. It is a mispreception that the timing of the hop is the most important
aspect of good time. It is not. 
Note that asdfasdfa has a std deviation of 109ms, while nist has 27ms which is
much better.
> Thanks,
> Ryan