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.

[Not to be confused with network timing, although the same clocks

are used to provide sources for "time" over different layer 1/2/3

protocols ]

-M

"Hannigan, Martin" <hannigan@verisign.com> 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

---Rob

Robert E. Seastrom wrote:

"Hannigan, Martin" <hannigan@verisign.com> 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