[ntp:questions] Beginner needs help...

Robert Hegner robert.hegner at hsr.ch
Mon Feb 28 12:25:40 UTC 2011


Hi all

I'm new to this list and also a NTP newbie. I'm trying to set up time 
synchronization in a simple local network.

Three computers are connected via a switch:
- 192.168.0.1 runs Win7. This should be the time server for the other 
computers. Its clock source is the local system clock.
- 192.168.0.2 and 192.168.0.3 run WinXP. They should synchronize to the 
time of 192.168.0.1

I use the Meinberg build of NTP 4.2.4 on all computers.

The configuration file for 192.168.0.1 contains the following two lines:
server 127.127.1.1
fudge 127.127.1.1 stratum 1

The configuration files for 192.168.0.2 and 192.168.0.3 contain the 
following two lines:
driftfile "C:\Program Files\NTP\etc\ntp.drift"
server 192.168.0.1 iburst

When the NTP service is not running, I can successfully set the time of 
the two clients using
ntpdate -b 192.168.0.1

Then, when I start the NTP service on the clients, offset is less than 
1ms in the beginning. But during the day, they drift away more and more 
(up to 50ms or so). Jitter is less than 0.5 on both clients.
The time server (192.168.0.1) shows up in green for both clients (in the 
Meinberg NTP Monitor) and the Reach value is 377. So I guess there is no 
network/connection/firewall problem (right?).

In Windows Event Viewer, I can see the following NTP related messages on 
the clients:
- ntpd 4.2.4p8 at lennon-o Dec 09 10:46:55 (UTC+01:00) 2009  (3)
- precision = 2.000 usec
- Listening on interface #0 wildcard, 0.0.0.0#123 Disabled
- Listening on interface #1 Loopback Interface 1, 127.0.0.1#123 Enabled
- Listening on interface #2 IP Interface 2, 192.168.0.2#123 Enabled
- frequency initialized 48.735 PPM from C:\Program Files\NTP\etc\ntp.drift
- synchronized to 192.168.0.1, stratum 2

So the clients seem to synchronize (only) once; and this last entry is 
several hours old now.

Why do the clients not update the time? Any ideas?

Robert



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