[ntp:questions] Proposed NTP solution for a network

Unruh unruh-spam at physics.ubc.ca
Tue Mar 3 21:32:44 UTC 2009

Jason <bmwjason at bmwlt.com> writes:

>Terje Mathisen wrote:
>> David J Taylor wrote:
>>> Jason wrote:
>>> []
>>>> G. What have I missed, or gotten confused?
>>> []
>>>> Thanks,
>>>> Jason.
>>> You forgot to say what the going rate is for the consultancy you want!
>>> <G>
> > Indeed. My standard rate is $200+ per hour.
> >
> > First of all: The 10s of us requirement within a site is _not_ feasible
> > without direct PPS sync on every server, and since your blades cannot do
> > this, the only alternative would be some other form of HW sync (like
> > having blades that can slave their master clock to the host enclosure,
> > and then using PPS to lock that master frequency).
>This is what I was afraid of. When queiried, the manufacturer responded 
>with, well, nothing. Like they'd never heard of such a thing.

> >
> > OTOH 100-1000 us is in fact quite doable using standard NTP.
>The critical time-stamp of the transactions must be tighter than 100us.

Sorry, you simply cannot do it. the computers themselves have all sorts of
internal processes which could delay things by 100us. Are you sure you are
not confusing millisecods with microsecods (usec) a microsecond is
1/1000000 of a second.  EVen if you slave
each computer to a GPS clock the internal workings can mess up the time by

Who is setting this standard?

> >
> > I would as a bare minimum configure two S2 servers at each site, both of
> > them as clients of all 3 GPS-based appliances, as well as 2-3
> > internet-based sources (either pool.ntp or a private peering agreement
> > with another nearby GPS-based company).
>Good info, I'll start looking for both trusted (probably authenicated) 
>and accurate private sources -- some of our interconnected customers 
>also have sources.

> >
> > Finally I would use the same NTP configuration on every single of the
> > remaining servers, syncing to all 6 of the secondary servers.
>Without a doubt -- I'm pushing the sys admins to reconcile every server 
>NTP config.

> >
> > Terje

>Thank you.


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