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

[K5ROE Mike]

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