"Richard B. Gilbert" <[EMAIL PROTECTED]> writes: >[EMAIL PROTECTED] wrote: >> Hello, >> >> I'm trying to configure a small network for high precision time. >> Recently acquired an Endrun CDMA time server that runs like >> a dream, tracking CDMA time to about +/- 5 microseconds. >> >> The clients are a rag-tag assembly of diverse systems including >> a Centos 4.5 Linux i686, Linux x86_64, Sun Ultra 10, Sun Ultra 80, >> IBM RS/6000 44p, Windows 2003 X64, and a Windows XP laptop. >> >> All are configured to prefer the Endrun clock and poll it on a >> 16 second interval. All are attached to a single SMC gigabit >> Ethernet switch with only the Endrun and two Sun systems running >> at a lower speed of 100 MBPS. Close to zero network traffic >> and system loads. >> >> All systems are running 'ntpd' 4.2.4p4. Compiled NTP native >> 64-bit for the Windows X64 system. [A #ifdef tweak to >> 'intptr_t' and 'uintptr_t' is required, will provide patch if >> desired]. >> >> It generally is working well, with the systems tracking anywhere >> from +/- 100 microseconds to +/- 500 microseconds most of the >> time. >> >> However once or twice a day, all the systems experience a >> random, uncorrelated time shift of from one to several >> milliseconds. ><snip>
>Forcing the poll interval to 16 seconds is not always a good idea! >Ntpd will select a poll interval, generally starting at 64 seconds, and >ramping up to as long as 1024 seconds as the clock is beaten into >submission! It is his network, he is not going to overload it. So, if he wants a 16 sec poll interval that is up to him. I agree it is not a good idea for remote servers, but on his own system it is fine. >Directly connected refclocks are frequently polled at shorter intervals >but I don't think your refclock is "directly connected" in the same >sense that a clock working through a serial or parallel port is directly >connected! >A clock connected via ethernet with all the latencies and jitter >thereunto appertaining is no different than any other network server and >should be polled in the same manner! ??? The longer polls are in order not to swamp the remote server whith 10000 people all polling every 16 sec ( or 1 sec) There is nothing in ntp itself that mandates a longer poll interval. In fact a shorter poll interval makes ntp much more responsive to changes ( clock drifts, etc) >The very short poll intervals correct large errors quickly and the very >long intervals correct small errors very accurately! No for a properly designed system both should be corrected. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
