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Re: ntp config tech note

  • From: Michael Sinatra
  • Date: Fri May 21 00:21:19 2004 
Robert E. Seastrom wrote:

"Hannigan, Martin" <[email protected]> writes:
That's NTPv4 isn't it?
I also prefer to use three peers vs. two. Always an odd number,
greater than 1. Assumptions can't be made about the mathematics behind time, but in a reference model, odd numbers are better.
Actually, three is not enough; Mills says at least four.  Diversity in
manufacturer (and controlling organization if you can spare the
cycles) is a big big plus. You may wish to read Dr. Mills' post to
comp.protocols.time.ntp in the wake of the TrueTime bug of the
2001->2002 new year:

http://groups.google.com/groups?hl=en&selm=3C32924F.994E1D01%40udel.edu
If you're really paranoid, diversity in reference sources should also be considered. You should have more than one stratum-1, and as a group they should get time from more than one of [GPS, WWV/WWVB/DCF77/CHU/JJY/ETC., USNO, ACTS, etc.] and your stratum>1s should get time from multiple stratum-1s of similarly diverse references.

Many NTP folk look down their nose at the radio sources, since GPS is more accurate. But if you already have a GPS stratum-1, then perhaps your next stratum-1 should be WWVB and friends, or you should have a backup assocation with someone who does. And remember that CDMA gets its time from GPS, so it doesn't "count" as a diverse source. Like I said, if you're really paranoid...

michael