I have 4 Windows client computers who get their time from a Windows Server 2003 machine, which in turn gets its time from 9 Stratum 2 servers, all but one within 150 miles. The clients easily experience offsets within +- 6 ms, except when I download a large file. In that case the offset immediately goes up to 300 ms or more, says steady for the duration of the download, and then declines to -300 ms, or vice versa; I don't remember exactly. The time offset will also occasionally become large when the ISP's router becomes congested, say when half a dozen neighbors are all downloading movies. The surprising result is how quickly the clients recover the correct time: within a minute or two.
I don't understand why you need the broadcast mode. It seems to me that NTPD is optimized for the client/server configuration. If you really want accurate time, the server should be synchronized to a local time source, such as a GPS clock. Charles Elliott > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On > Behalf Of David Taylor > Sent: Thursday, September 27, 2012 10:47 AM > To: [email protected] > Subject: Re: [ntp:questions] NTP client configuration > > On 27/09/2012 07:08, Benjamin CABUT wrote: > > Hello, > > > > We are using Meindberg NTP client and server. > > > > Our configuration is: > > - 1 Computer under windows that is server server 127.127.1.0 > broadcast > > 192.168.2.255 minpoll 4 maxpoll 4 iburst disable auth > > - several computer under linux + computers under windows, client of > > this > > server: > > server 192.168.2.250 minpoll 4 maxpoll 4 iburst broadcastclient > > disable auth > > > > > > My problem is the following: > > Mainly on windows computer, sometime, depending what the computer is > > doing, there is a big offset between clients and server. > > ("Big" for me is more than 500ms). > > > > I would like to know if it is possible to setup client so as soon as > > he see offset>500ms, then client do a "fast" synch. (STEP). > > > > > > Another way to solve my problem could be for me, to modify the source > > code of my application in order to get this "offset" information > > inside my code (C or C++ langage). then I could add this offset to > the > > time of the computer in order to be as much accurate as possible > > during the time the offset is bigger than 500ms. > > > > Do you have any solution? > > > > Regards. > > > > B CABUT > > I haven't used "broadcast" or "auth", so I don't know if that affects > things. My understanding of NTP was that unless you configure it > otherwise, an offset exceeding 128 milliseconds would force NTP to step > the PC's clock rather than changing the rate, so I am surprised you are > seeing 500 ms offsets. > > I'm using NTP 4.2.7p285 (updated from the Meinberg installation) and > seeing offsets in the millisecond range (except on a couple of PCs > where it's the "few milliseconds" range). This is with three local PCs > as > stratum-1 servers, with a GPS reference. > > See: > http://www.satsignal.eu/mrtg/performance_ntp.php > > I would not recommend using the "local clock", and if you need an > isolated network I suggest looking into "orphan" mode (about which I > know nothing). > > Cheers, > David > -- > Cheers, > David > Web: http://www.satsignal.eu > > _______________________________________________ > questions mailing list > [email protected] > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
