Information about Time Server

[Xavier]

I would like to have some informations about the software time-server-monitor: My project is to synchronize the clocks of 3 PCs connected with a LAN network.I don´t care if the clock of the three PCs is put right , I only want that the three PCs have the same clock with a precision of 20 ms ! I don´t dispose of an internet connection.Thus, I want that one of the three PCs to be an Time Server and that the two others be Client of this Server but I don´t know how to do this...or if it isn´t possible with this software.
I hope someone can help me!
Many thanks,
Xavier

[Gregoire Diehl]

Xavier,

please note that the NTP Time Server Monitor is just a monitoring and configuration tool for an underlying NTP service.

You can download an NTP Service for Windows from:
http://www.meinberg.de/english/sw/ntp.htm

NTP can work as Server and Client simultaneous. You can setup the correct configuration already during the installation on the page "Configuration Options".
One of the 3 computers should be the master and the other two computers should work in client mode.

The setup for the master should look like this...:


... and for the client like this:


Replace the string IP_OF_TIME_SERVER in the picture above with the ip address of your desired NTP Master (Server).

Afterwards you can check with the NTP Time Server Monitor that everything is running corretly.
On the NTP Status tab you should see a green line with the IP or Hostname of your NTP Master (Server) after a few minutes. This indicate that client is synchronized to this NTP server.
On your NTP server you should see also a green line with the entry LOCAL(0). This means that NTP is synchronized to its local clock and will provide this time to other clients in the network.

BTW: You can check the status of your NTP service using the NTP Time Server Monitor only on one computer. Just click the right mouse button on the status page and add select "Add new server". Just insert the ip or the hostname of the computer you want to monitor and press enter. Afterwards you should see a new rider next to "Localhost".


Gregoire

[Xavier]

Thank you very much for your answer!The synchronisation works!But I have noun another problem: after the synchronisation i have i good precision,but the difference between the clocks grow up enough quickly, I mean that I would like that the difference between the clocks believes under 1ms all the time!Is it possible to refresh every 5s (for example) to preserve the difference between the clocks under 1ms?
Another question: Is it normal that the synchronisation takes approximately 5 minutes?

Thank you,

Xavier

[Gregoire Diehl]

I mean that I would like that the difference between the clocks believes under 1ms all the time!

In general you can expect an accuracy of about 1-10ms using NTP under Windows. The reached accuracy is also depending on the used network topologie.
In fact Windows is really a lousy timekeeper.... so i see no possibility to reach an accuracy of better 1ms continuously without an integrated reference source.

Is it possible to refresh every 5s (for example) to preserve the difference between the clocks under 1ms?

NTP send a request to the upstream server every 64 seconds per default. If the time synchronization is steady state then this intervall could rise till 1024 seconds. NTP is managing the polling intervall according to the circumstances and in fact there is no need for an an intervention. However if you would like to rule the polling intervall yourself you can use the MINPOLL and MAXPOLL parameter. The possibile range is from 4-10 means 16-1024 seconds (2^4=16 2^10=1024).

To specify a maximum polling intervall of 16 seconds you have to alter the server line in your config file like this:
server ip_of_your_ntp_Server MINPOLL 4 MAXPOLL 4

Another question: Is it normal that the synchronisation takes approximately 5 minutes?

Yes. NTP needs some polling intervals (send a request to the server) before selecting a source. The additional keyword iburst will speed up the initial synchronization process.
server ip_of_your_ntp_Server MINPOLL 4 MAXPOLL 4 iburst

Gregoire