OFFTOPIC [Re: NTP accuracy?]

Kris Karas (
Wed, 02 Dec 1998 14:35:31 -0500

Larry McVoy wrote:

> ...suppose you had 1,250 systems...
> how accurately can NTP sync the clocks across all those machines?

Accurately enough for most purposes - within one linux HZ off (10 millisecs).
Put NTP on your router, and have it broadcast the packets, rather than each
machine polling. Even with polling, some newer NTP features (e.g. burst mode,
which you can get if you run NTP-4) will let you achieve amazingly accurate
results over miserably-poor connections. For example, I have a machine here
which achieves 8 millisecond accuracy over a link that has propagation delays
of 200 milliseconds and jitter of 100 milliseconds. It can be done.

Kristofer Karas                           * (delete X's)
AMA/CCS DoD RF900RR HawkGT !car           *    Senior systems engineer/SysAdmin
"Build a system that even a fool can use, * BI Deaconess Medical Center, Boston
 and only a fool will want to use it."    *  Will design LISP machines for food

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