On 2009-01-08, Charles Brown <charles.br...@sensis.com> wrote: > I have a processor with a serial GPS on a closed private network. If > the GPS is not locked, or the GPS inputs are missing, I still want the > ntpd to serve *some* time, perhaps from the undisciplined local clock.
ntpd _never_ serves time "from" the Undisciplined Local Clock. All that the Undisciplined Local Clock driver does is allow ntpd to claim to be synced in the absence of a real time source. > I.e., the server can't just do nothing. Does the GPS driver do that > automatically, or do I have to configure two drivers in the ntpd.conf? > Perhaps something like; > > prefer peer 127.127.20.u > peer 127.127.1.u That's all wrong. Use something like this: # GPS # see the type-20 driver page for the mode value server 127.127.20.0 mode X minpoll 4 maxpoll 4 # Undisciplined Local Clock server 127.127.1.0 fudge 127.127.1.0 stratum 10 > Suppose I have a second server, with a higher precision oscillator, > on this same network. How would I configure that? Perhaps; > > prefer peer morePreciseServer # should be best source > peer 127.127.20.u # next is the GPS > peer 127.127.1.u # if all else fails... The best thing to do is let NTP choose the best time source. But keep in mind that NTP needs at least 3 time sources to choose the one that is the best. When NTP has only two time sources it has no way of deciding which one is correct. >What would the configuration on the other processor look like? Perhaps; > > prefer peer 127.127.22.u # always best > peer 127.127.1.u # if GPS fails, still better for a > # couple of days > peer lessPreciseServer # GPS missing a long time, > # lessPreciseServer might have GPS I don't understand this configuration example. Unless the "better" system is using an _extremely_ high quality oscillator is will most likely not be materially "better" than the fist system. -- Steve Kostecke <koste...@ntp.org> NTP Public Services Project - http://support.ntp.org/ _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
