[ntp:questions] why do internet servers not poll at longer intervals

Charles Elliott elliott.ch at verizon.net
Wed Feb 15 15:10:24 UTC 2012


My experience with the NY NIST server (nist1-ny.witime.net =
nist1-ny.ustiming.org [64.90.182.55]) is that it is 6 ms ahead of any other
clock on the Internet.  I wrote to the person who maintains the government
time servers about it, but his response was not encouraging.  You could
compare it to several other servers in the area, particularly
clock.nyc.he.net, to see if it is still ahead.  Whoever suggested using the
stratum 2 time servers had a good idea.  They are not heavily used at this
point in time.  I selected 12 that were geographically close together, and
eventually winnowed it down to 8 that all give nearly the same time and
don't have large jitter.  However, nothing helps in the middle of the day
when the whole Internet is congested.

My BU-353 GPS device w/o PPS consistently gives ±4 ms jitter, with the rare
excursion to ±6 ms, except that every other day it apparently loses sync
with the satellites and gives ±80 ms for about 4 hours. I live with it
because it is still better than the Internet time servers when the network
is busy.

Charles Elliott

> -----Original Message-----
> From: questions-bounces+elliott.ch=verizon.net at lists.ntp.org
> [mailto:questions-bounces+elliott.ch=verizon.net at lists.ntp.org] On
> Behalf Of Ron Frazier (NTP)
> Sent: Wednesday, February 15, 2012 3:43 AM
> To: questions at lists.ntp.org
> Subject: Re: [ntp:questions] why do internet servers not poll at longer
> intervals
> 
> On 2/15/2012 3:23 AM, David J Taylor wrote:
> >> +nist1-ny.ustimi .ACTS.           1 u   25   64  377   53.990
> >> 3.458 6.160
> >> #216.119.63.113  .ACTS.           1 u   42   64  377   59.998
> >> 22.534 5.595
> >> +india.colorado. .ACTS.           1 u   36   64  377   63.986
> >> 1.739 6.604
> >> +ping-audit-207- .ACTS.           1 u   50   64  377   83.998
> >> 0.715 3.206
> > []
> >> Ron
> >
> > Ron,
> >
> > What Internet connection do you have?  I see delays of 25 - 35 ms on
> > my cable modem connection, which is 30 Mb/s down and 1 Mb/s up.  I
> > don't know whether delays of 54 - 84 ms are what would be expected on
> > your connection, but they seem long delays to me.  It may be worth
> > checking whether your ISP has an NTP server.  Sometime stratum-1 NTP
> > servers can get overloaded because too many people connect to them,
> > and stratum-2 servers will give better results (especially if they
> are
> > better connected to you).
> >
> > Cheers,
> > David
> >
> 
> Hi David,
> 
> My PC connects to my basement router with wifi G, which is then wired
> to
> a wired router which is wired to the cable modem.  Service is Comcast
> 16-20 Mbps down and 3-4 Mbps up.  I get pretty low jitter to the NY
> NIST
> server, which is the one this machine normally hits if there is no GPS.
> I'm not sure if Comcast has a public NTP server or not.
> 
> Sincerely,
> 
> Ron
> 
> 
> --
> 
> (PS - If you email me and don't get a quick response, don't be
> concerned.
> I get about 300 emails per day from alternate energy mailing lists and
> such.  I don't always see new messages very quickly.  If you need a
> reply and have not heard from me in 1 - 2 weeks, send your message
> again.)
> 
> Ron Frazier
> timekeepingdude AT c3energy.com
> 
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions



More information about the questions mailing list