[ntp:questions] Number of Stratum 1 & Stratum 2 Peers

Harlan Stenn stenn at ntp.org
Tue Dec 2 05:59:33 UTC 2014

edstuart at gmail.com writes:
> Hi,
> I am looking to implement an NTP network and I was reading
> http://support.ntp .org/bin/view/Support/DesigningYourNTPNetwork.  It
> suggests 4 stratum 1 peers and 4 stratum 2 peers well.  I understand,
> that the document recommends this so that if one of the servers in a
> stratum dies, there will still be 3 servers from which a majority
> clique should be found.  The problem is that we will be starting out
> with simply 100 nodes at most.
> At the same time, we want drift less than 1 second.  However, over the
> next 7 years or so, we should hit ~ 1000 NTP clients.  Is the
> document's recommendation overkill for my situation?

"It depends."

What (and who) will it cost if this design/deployment goes wrong?  What
will it cost if your machines drift away more than a second?  Do you
need to keep good time even if no external timesources are available?
If so, for how long?  How well-synch'd do your clients need to be with
each other?

You can get a decent S1 source for not a lot of money.  It won't keep
decent time for long if no external sync source is available.  You can
do much better if you start spending more (maybe US$3,000 or so).  You
can do better than that if you spend even more.  In 7 years' time it
might be much better to be ready for PTP as well.

You have a lot of choices.  What you should buy really depends on what
your actual requirements are (and those requirements might cover a
fairly wide area).

Please let me know if I can help more.
Harlan Stenn <stenn at ntp.org>
http://networktimefoundation.org - be a member!

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