[time-nuts] Re: NIST NTP servers way off for anyone else?

[Adam Space]

Yeah I think it is localized. Network paths have been quite variable for
me. Every once in a while I start getting massive delays from the NIST
servers to my system, resulting in results like yours.

Interestingly though, time-e-g was one of the only servers that didn't have
this problem for me. This is a recent wedge plot for it. seems to be
working fine for me now, just with a variable outgoing delay causing
positive offsets, which seems to be more of a problem with my connection
than anything else.

On Tue, Dec 14, 2021 at 9:04 PM K5ROE Mike <K5ROE at roetto.org> wrote:

> On 12/14/21 5:23 PM, Hal Murray wrote:
> >
> >> Out of curiosity, since you monitor NIST Gaithersburg, if you were to
> average
> >> over the offsets for a whole month, what kind of value would you get?
> Surely
> >> it is close to zero but I am curious how close. Within 1ms?
> >
> > It depends.  Mostly on the routing between you and NIST.  If you are
> closer,
> > the routing is more likely to be symmetric.
> >
> >  From my experience, routing is generally stable on the scale of
> months.  There
> > are short (hours) changes when a fiber gets cut or a router gets busted.
> > There are long term changes as people add fibers and/or change business
> deals.
> >
> > There are some cases where a stable routing will produce 2 answers: x%
> of the
> > packets will be slightly faster/slower than most of them.  I think what's
> > going on is that the routers are doing load sharing on multiple paths,
> hashing
> > on the address+port.  Or something like that.  So it's a roll of the dice
> > which path you get.
> >
> > --------
> >
> > I'm in California.
> >
> > NIST has NTP servers at 3 locations in the Boulder CO area: NIST, WWV,
> and
> > Univ of Colorado.  (Google maps says WWV is 60 miles north of Bouler.
> Univ of
> > Colorado is a few miles from NIST.)
> >
> >  From a cheap cloud server (Digital Ocean) in San Francisco, the RTT to
> NIST is
> > 31.5 ms, to WWV is 32.1 ms, to Univ of Colorado is 54.5 ms.  The time
> offsets
> > are about 1 ms for NIST and WWV and 12 ms for Univ of Colorado.
> >
> >  From my home (AT&T via Sonic), 30 miles south of San Francisco, the
> RTTs are
> > 61 ms for NIST and WWV and 81-82 for Univ of Colorado.  Offsets are 6-7
> ms for
> > NIST and WWV and 4-5 ms in the other direction for Univ of Colorado.
> >
> >
>
> Might be a localized routing phenomenon.  Using my verizon connection from
> Northern Virginia the results are awful for time-e-g.nist.gov:
>
>       remote           refid      st t when poll reach   delay   offset
> jitter
>
> ==============================================================================
> -192.168.1.219   68.69.221.61     2 u   56   64  377    0.400   -0.290
>  0.035
> *192.168.1.224   .PPS.            1 u    1   16  377    0.184    0.087
>  0.017
> -129.6.15.26     .NIST.           1 u   32   64  377   93.087  -37.940
>  7.867
>
> However from my AWS machine in Oregon:
>
> MS Name/IP address         Stratum Poll Reach LastRx Last sample
>
> ===============================================================================
> ^- 152.63.13.177                 3   6   377    63  -2011us[-2011us] +/-
> 128ms
> ^+ 209.182.153.6                 2   7   377    65   -959us[ -959us] +/-
>  86ms
> ^- 64.139.66.105                 3   6   377   128  -5838us[-5838us] +/-
> 134ms
> ^+ 129.6.15.26                   1   6   377    64  -2075us[-2075us] +/-
>  37ms
> ^* 173.66.105.50                 1   8   377   438   -448us[ -870us] +/-
>  38ms
>
>
> -mike
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