[ntp:questions] Re: NTP, no external time source, peering "Undisciplined Local Clocks" ?
torres at pop-pr.rnp.br
Wed Oct 19 21:43:49 UTC 2005
one-time mode may help Eric?
Em Qua 19 Out 2005 18:52, David L. Mills escreveu:
> As confirmed by experiment, having each client average all the others is
> not a good idea. The ensemble tends to do a random walk and display very
> poor statility. Better to pick one of them and let it time the rest.
> However, folks have tended to extend this idea to provide a multiple
> backup capability. This is a bad idea, as evil timing loops can form
> that take a long time to count to infinity.
> There is a new wrinkle designed for isolated configurations with
> multiple backup requirements. It is called orphan mode and works best
> with broadcast/multicast networks or networks with multiple
> symmetric-mode networks. The networks self-organize, elect a leader and
> pecking order depending on the particular failure topology. It's been
> tested here in the ntp-dev version, but should still be considered
> experimental. See the documentation on the authentication options and
> miscellaneous commands pages in the online documentation.
> Eric wrote:
> > On Tue, 18 Oct 2005 14:19:11 GMT, mmolteni at cisco.com (Marco Molteni)
> > wrote for the entire planet to see:
> >>Say I don't know if a clock is better than the other, so by configuring
> >>B and C to use A as server I risk to have a not so good time if A is
> >>Can I configure A,B,C to peer with each other in a meshed fashion, so
> >>to have each clock influenced by all the others?
> > The general feeling on this ng is that this is not a good application
> > for NTP.
> > I would go further, and say it is a poor design using any type of
> > software. Sure, you may get some weird approximation of the average
> > clock errors around your network, but it will still drift, by an
> > unknown amount.
> > Three PCs, all of which don't know the time, can't really help each
> > other find it.
> > - Eric
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Pedro Rodrigues Torres Júnior
RNP / PoP-PR
Tel: 55 41 3361-3343
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