Cannot synchronize to server with local clock
- From: brian.t.brunner@xxxxxxxxxxxxxxx (Brian T. Brunner)
- Date: Thu, 21 Jul 2005 13:37:17 GMT
Can you shed some light on whether the 'stratum 8' tactic should be
a 'server' line, or should it be a 'fudge' line?
Here's the example ntp.conf=====
restrict default ignore
restrict 127.0.0.1
restrict 192.168.1.0 mask 255.255.255.0
server mytrustedtimeserverip prefer # scada/master (PC w/human w/ mark-1 eyeball & timex)
server 127.127.1.0 stratum 8 prefer # new release has this line for local clock when scada is down & site depends on me
fudge 127.127.1.0 stratum 8 # previous release had this line to accomplish the above line...
driftfile /etc/ntp/drift
=====Should I take out the 'fudge' line, or the 'server ... stratum 8 prefer' line?
Here's the gotchya: I'm not guaranteed to *have* a scada,
and if it crashes I'm the time master for the 0-11 other systems in the site
until it comes back.
Where does LOCAL appear? ntp.conf?
Brian Brunner
brian.t.brunner@xxxxxxxxxxxxxxx
(610)796-5838
>>> serge.bets@xxxxxxxxxxxxxxxxxxxxxx 07/20/05 06:25PM >>>
On Wednesday, July 20, 2005 at 9:32:31 PM +0930, Tim wrote:
> I have dial-up internet, so my network is only ever on the net some of
> the time. I had that machine run a local clock, since the machine is
> always running, and used it as the clock server for my LAN (so they
> all stayed in step with each other).
Yes, that's one of the usages of LOCAL(), undisciplined or rarely
disciplined, fudged at a high stratum like 8 or 10.
> If I remember correctly, its stratum changed from 16 when unsynced, to
> one less than the source it uses for synchronising (when in sync with
> it).
The LOCAL() driver stratum is fixed. The *server* stratum varies from 16
at startup to +1 of it's current syspeer, be it an Internet server or
the LOCAL() driver. Your other LAN clients in turn are current stratum
of server +1.
> the computers keep time well enough, just free wheeling along
> individually, that they could carry on as they were until the next
> time the LAN was connected to the internet.
So you removed LOCAL()? Without sync machines will diverge. Perhaps
enough to take longer to sync during short online sessions. Or worse
begin to sync with a large frequency peek just when you hangup, then
continue free wheeling but on a this anormal frequency. Finally a client
(re)booted will have false time until next dialup, if ntpd has not died
before on "no servers reachable". Not good.
My advice for you would be to set a 127.127.1.0 stratum 8 prefer on your
server, and another one stratum 14 (but not prefer) on a given client.
This way you have eternal sync, only one sync source at a time, and you
can shutdown server *or* given client for maintenance.
Serge.
--
Serge point Bets arobase laposte point net
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