[ntp:questions] delay in stats

edouard funke korlaz at gmail.com
Thu Mar 1 13:15:53 UTC 2007


I am running some tests on the NTP protocol for my company : I need to
achieve (if possible) in LAN a precision (for clients) of about 1
millisecond (or less :-))

1. the following properties are studied :

- the time for a client to "calibrate" its clock
o with/without iburst mode
o with/without drift file
o with fixed drift
o with different values for max polling

- the maximum precision achievable for clients :
o with different values for max polling
o with huff n'puff filter
o with all clients in « peer » mode or at least some of them

the NTP  server clock reference will be :
o undisciplined local clock
o internet stratum 1 or 2
o GPS (i have a meinberg lantime M300 and PCI card + GPS receiver on loan)

I am trying to know here which configuration parameters can improve
the "calibration" speed and maximum precision of clients clock.
I am not trying to have the exact time on clients but rather, that all
clients have the same time.

I must run NTP daemon on Windows Server 2003 SP1 and it almost sure
that, in the end, NTP servers wont be able to have internet connection
or even GPS : they are included in tests because i want to determine
the impact of the server precision on the client precision.

For the GPS, i know there is some hardware solution that can run in
free-run mode after 24h calibration (meinberg).

I am sure it is a commun problem but i couldn't find any good reports
on it : if you have some that might interest me, that would be great

2. I just checked the ntpd 4.2.4 changelog : is the windows multimedia
timer enabled by default ? Where can i find some informations on it ?

3. I would like to know if there is a way to display the delay in ms
in loopstats stats ? I am actually talking about the delay column in
ntpq -p.

Ok, i am stopping there :-) I know i am asking a lot ! I just need
some infos about how to proceed for my tests to be as accurate as


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