On 2008-11-19, Mike Griffin <[EMAIL PROTECTED]> wrote: > I have an isolated network which has no connections to the outside > world. This includes any type of modem access. > > The machines are running Red Hat Enterprise Linux 5.2 and I also have > Cisco routers involved. What I would like to do is to assign one of my > RHEL machines as my NTP server
This is trivial to set up. # Server /etc/ntp.conf driftfile /path/to/ntp.drift server 127.127.1.0 minpoll 4 fudge 127.127.1.0 stratum 10 The ntpd using this configuration file will be able to answer client queries approximately 55 seconds after is starts up. If at all possible I would set up the time server in a location with similar ambient conditions as your time-island and allow that ntpd to poll some real time sources for 24 hours so that it has ample time to calculate a resonable frequency correction to be stored in the drift file. I would also give serious consideration to using a dedicated real physical time server system (i.e. not in a VM) which does not run _any_ services other than ntpd (and the minimum number of administrative cron jobs). > and have it synch off its local system clock. ntpd can not "sync off its local system clock". ntpd can use either the Undisciplined Local Clock or Orphan Mode to _claim_ to be synced to a time source even though it is actually free-wheeling. Orphan Mode is the designated replacement for the Undisciplined Local Clock. However, in certain configurations (e.g. a time-island) the Undisciplined Local Clock aparently must be used. > I'm not concerned with time accuracy to the real world, I just need > time relevance within the network. You _should_ be concerned about clock stability. ntpd is not a magic box which can produce stable clocks out of thin air. It needs a reference standard towards which it will steer the clocks. Without a reference standard your client systems will be following a moving target. This reference standard could be, and usually is, UTC acquired over a network or via a GPS/WWVB/etc receiver or via a POTS modem. This reference standard could also be generated locally using a high quality (e.g. rubidium) oscillator to provide a PPS or 10MHz reference signal. -- Steve Kostecke <[EMAIL PROTECTED]> NTP Public Services Project - http://support.ntp.org/ _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
