Richard B. gilbert wrote: > Spoon wrote: >> Keith E. Brandt, M.D. wrote: >> >>> 'Poll' is the polling interval in seconds, which seems to vary quite >>> a bit on my system, so here's the first real question - how does ntp >>> pick the polling interval (a pointer to the docs is fine, I just >>> haven't been able to uncover it yet). >> >> Have you played with minpoll and maxpoll? >> >> http://www.eecis.udel.edu/~mills/ntp/html/confopt.html >> >> minpoll minpoll >> maxpoll maxpoll >> >> These options specify the minimum and maximum poll intervals for >> NTP messages, in seconds as a power of two. The maximum poll interval >> defaults to 10 (1,024 s), but can be increased by the maxpoll option >> to an upper limit of 17 (36.4 h). The minimum poll interval defaults >> to 6 (64 s), but can be decreased by the minpoll option to a lower >> limit of 4 (16 s). These option are valid only with the server and >> peer commands. >> >> I don't know under what conditions ntpd changes the polling interval. > > Playing with MINPOLL and MAXPOLL is NOT recommended!! > > Ntpd varies the polling interval between MINPOLL and MAXPOLL in order to > best respond to existing conditions. The math is over my head but it > has something to do with the "Allan Intercept" q.v. > > My oversimplified English explanation is that short polling intervals > allow large errors to be corrected quickly while the longest polling > interval allows small errors to be corrected very accurately.
I would have thought that short polling intervals are always better, ignoring traffic overhead issues: If the current "correct" interval should have been e.g. 64 seconds instead of 16 seconds, just ignore 3 out of 4 replies. Where is the flaw in my logic? Regards. _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
