[ntp:questions] Re: ntp client over satellite and no CMOS battery

David L. Mills mills at udel.edu
Wed Oct 5 01:51:31 UTC 2005


Bob,

See the calldelay command in the documentation. Used with iburst, it 
controls the interval between the first packet in the burst and the 
second. This gives time for the link to set up before pounding on it in 
earnest.

Dave

Bob Beers wrote:
> Hello again all,
> 
> While it was an interesting excursion, I wonder if I could bring
> this thread back around to the original topic?
> 
> There have been a few other threads recently which touch a bit on
> the same subject matter and I have learned a bit from them.
> 
> sync immediately
> ntpd for dummies
> ntpd and hwclock
> 
> I still have not completely solved my original problem,
> which I will restate now:
> 
> 
> A linux unit (basically an ntpd client) without a hwclock battery
> lives on the remote side of a satellite connection. Every time
> it comes alive from power cycle, the hwclock sets the system clock
> to 2000-Jan-01.
> 
> Under ideal circumstances, the network is available before the client
> starts ntpd -g -N, and all is well; the system clock is set to
> current time very quickly. I have a 3 line ntp.conf on the client:
> 
> server 172.16.87.11 <http://172.16.87.11> iburst
> driftfile /etc/ntp.drift
> logfile /var/log/ntp.log
> 
> ( where 172.16.87.11 <http://172.16.87.11> is my linux ntpd server on the
> internet side
> of the satellite using four pool.ntp.org <http://pool.ntp.org> servers, and
> restricted
> to only serve time to my clients )
> 
> However, sometimes, the network link does not become available until
> after ntpd has been started. If the initial iburst to the server
> doesn't get any reponse, and then the network does become available,
> it takes several minutes vs. a few seconds to get the clock set.
> 
> Q1: Can I modify that behavior?
> 
> If not, I have in mind to run a cronjob which tests network connectivity
> to the ntpd server and (re)starts ntpd, to get the quick clock adjust once
> the network is available. I would still need to detect when the state
> was "good", and then could set my hwclock manually (optional) and cancel
> the cronjob.
> 
> Better ideas most welcomed.
> 
> This is important (to me) because I have an app to run on the client
> which uses timestamps, and I want to delay starting the app until after
> the system clock is set, but, of course, as quickly as possible. And
> I don't want to delay the rest of the boot process, just the one app.
> 
> Thanks,
> 
> -Bob
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