[ntp:questions] Isolated network

Richard B. Gilbert rgilbert88 at comcast.net
Wed Nov 19 23:21:00 UTC 2008

Mike Griffin 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 and have it synch off its local system
> clock. The other machines and routers would synchronize off this
> assigned server.
> I'm not concerned with time accuracy to the real world, I just need
> time relevance within the network.
> I have searched and it seems to be extremely difficult to find good
> guidance for this.
> Thanks in advance.

If at all possible, get some sort of "hardware reference clock".  A GPS 
timing receiver works very well.  Garmin offers one for less than $100 US.

It is extremely difficult to get tight synchronization without a stable 
reference.  Think of one drunken driver trying to follow another!  A GPS 
receiver gives you a stone cold sober driver who is right between the 
painted lines.

If you don't mind differences between machines that might be as large as 
a second or two, save your money!

More information about the questions mailing list