On Sun, May 12, 2013 at 1:34 AM, Esa Heikkinen <[email protected]> wrote: > Jason Rabel kirjoitti: > >> I think nobody ever really bothered to fix anything since the NTP time was > >> "good enough". > > Yes - definitely... If it's only used for NTP then the 10 usec error is > totally insignificiant.
A startum one NTP server typically runs with abot 2 uSec error fro UTC. ButA stratum two server, that means one that gets time from the strum one over the network NTP solution seems to be quite inaccurate, if I poll > my server from http://support.ntp.org/ntpq.php the results can vary couple > of milliseconds every time. Most Statum One NTP server are better then 10 uSec. 2 uSec is about what you should shoot for. It shouldn't work that way. What NTP does is discipline a local clock. It take hours or days before it settles and a lot depends on how good the local oscillator is. Mostly your local oscillator is just a TTL can that cost about 50 cents solder to a PC mother board. The the error in one "poll" does not matter to much because hundreds of them will be done and NTP wil make tiny adjustments to the locals clock's RATE. NTP is not adjusting the time, it adjusts the rate. (OK there is one time exception if the time is found to tbe far off) It does not do an adverse of servers. It compares them to find the best subset. This stops a broken server from polluting the average. Yes there might be a 10ms error in a polled time Bt what NTP is doing is noteing the local time, letting the local clock run for say 20 minutes then comparing to the server(s) to see if the local clock is fast or slow. So that 10ms error is only parts per million. It is not a 10ms absolute error in UTC time. If your local oscillator were better then NTP would open up that 20 minutes window and if the results aren't good it closes it down. It tries to keep several of those 20 minute intervals open at once. On the other hand SMTP, to thing that Windows uses simply gets the time and jumps the local clock to match and that's it. It does not discipline the rate. SNTP is a one-time thing -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
