[ntp:questions] Re: Setting Up NTP Subnet

Bill Myers whmyers at gmail.com
Wed Mar 8 16:30:20 UTC 2006


On 3/7/06, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>
> Bill Myers wrote:
> >  I have questions regarding best practices on architecture of NTP
> subnets.
> > I've thoroughly read "Notes on Setting up a NTP subnet" from the NTP
> sites.
> >
> > Is there a need for multiple external time source TECHNOLOGIES.  That
> is, is
> > it sufficient to use multiple (8) GPS receivers with ACTS dial backup
> > and Rubidium clocks?   This is a sizeable investment for the
> infrastructure,
> > but is it the right way?  Is it necessary or desirable to have other
> sources
> > such as radio and/or Internet?
> >
> > In case you have not picked up on it, I'm talking about an appliance
> here.
> > I find it odd that one cannot NTP peer these appliances.  This suggests
> to
> > me that we should create a stratum 2 tier peer layer a stratum 3 tier
> that
> > peers and serves time to the endpoints.
> >
> > More dysfunction?  The plan is for the stratum 2 tier, which is also the
> > time distribution tier, to be the cache DNS for some high-volume data
> center
> > environments.
> > _______________________________________________
> > questions mailing list
> > questions at lists.ntp.isc.org
> > https://lists.ntp.isc.org/mailman/listinfo/questions
> >
>
> It depends strongly on your needs for correct time and reliability.  You
> have not really specified your requirements. Are you serving a single
> site or multiple sites?  How far can your time deviate from UTC?   How
> much money are your willing and able to spend?
>
> If you absolutely must have sub millisecond accuracy and 100 percent
> reliability then you need to allow for:
> 1. Failure of a reference clock (GPS receiver)
> 2. Failure of the GPS System (insane satellites, jamming of GPS
> frequencies, etc.)
> 3. Failure of one or more of your lowest stratum servers.
> 4. Things neither you nor I have thought of or can think of!
>
> So tell us more and maybe we can give you better advice.


Reliability and synchronization is most important.  <10 millisecond accuracy
is probably sufficient.  Large financial with 100's of locations.
International.  Has experienced financial loss due to NTP failure.

~Bill

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