[ntp:questions] Problem with NTP multicast server configuration
brad at stop.mail-abuse.org
Sun Jan 16 01:11:45 UTC 2005
At 4:47 PM -0600 2005-01-15, Larry Mills wrote:
> - Two hosts (hosts X and Y) are configured as NTP multicast servers; each
> server is a peer of the other, in symmetric-active mode.
Use either one server or at least three. Two servers is the
worst possible configuration, see
Other than that, if you want the servers (and clients) to keep
reasonably accurate time, you'd need to add an external refclock.
A GPS with OXCO (Oven Stabilized Crystal Oscillator) would be
ideal, but that would require a connection to the outside world,
albeit not to the Internet. Other alternatives of this sort would
include a radio refclock (DCF77, CHU, WWV/WWVB/WWVH, etc...), a CDMA
refclock, or even simple dial-up ACTS modem service.
If you cannot have any kind of connection to an outside source,
then you could have an OXCO or TXCO (Thermally Compensated Crystal
Oscillator), and at least that would have less drift and less
variation in drift than the standard CPU clocks that you have in your
But you really should read through all of
ideally also the rest of the stuff at
Of course, there's also the NTP FAQ at
<http://www.ntp.org/ntpfaq/NTP-a-faq.htm>, and the official NTP
Brad Knowles, <brad at stop.mail-abuse.org>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/> for more info.
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