On 2007-05-18, Richard B. Gilbert <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote:
>> I have an old legacy external system that I need to synchronize with >> that sends custom protocol UDP packets containing a single field in >> the packet that contains the legacy system's current clock time (in >> milliseconds). > > Since your internal systems are already synchronized using NTP, it > should be fairly trivial to install ntpd on the external system and > get it synchronized too. Not if that old legacy system isn't an architecture that ntpd has been ported to. >> The current clock time starts at 0 when the system boots and >> increments forever thereafter. The frequency of this message is at >> least every 10 seconds, not 1 PPS like I would like. <snip> >> My hope is to have my internal system's NTP server receive the 10 >> second clock pulses from the old legacy system over UDP and have my >> internal system's NTP server synchronize with it. Use a daemon that listens to the UDP clock pulses and, after suitable preprocessing, sends them to ntpd via the SHM driver. >> I read this fine article (which I think is the path to take) but I >> need a clearer explanation on what to do. >> >> http://www.ee.udel.edu/~mills/ntp/html/extern.html > > I think that, in the article you refer to, Dr. Mills is referring to a > system or a hardware clock that actually knows what time it is! The stability of the time base is of primary importance. Numbering the seconds is trivial in comparison. > Your external system has no clue what time it is as we understand it. > It just ticks periodically and the period is apparently "approximately > ten seconds" Actually, it sends a packet containing the clock counter (ostensibly milliseconds since system startup) approximately every ten seconds. That's not the same thing as "just tick[ing] periodically". -- Steve Kostecke <[EMAIL PROTECTED]> NTP Public Services Project - http://ntp.isc.org/ _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
