Jan Hoevers wrote: > Chuck wrote on 27-10-2007 19:26: >> , but suddenly i am wondering why am i >> doing all this work to split nanoseconds when time across the net no matter >> what will never resolve even to microseconds. > > Don't agree. > My stratum 2 pool server has an offset far below 1 ms almost all the > time. No trickery, except careful configuration and server selection. > Running FreeBSD (nanokernel is standard). > Have a look if you want: ntpq -pc awk.xs4all.nl. > > Now that it's getting colder here my central heating is spoiling the fun > a bit... > > Jan
Right, but your system is only *accurate* to it's synchronization distance, which is the root dispersion + 1/2 the root delay. Your server, as viewed from my stratum one, has rootdelay=29.432 ms and rootdispersion=46.082 ms. That's a synch distance of 60.798 ms, even though your reported offset in the same output is offset=-0.939 ms. My stratum one has an offset of offset=0.000, but has rootdelay=0.000 and rootdispersion=0.280. So it's only accurate to 280 us, but over the wire it degrades a lot. One of my stratum twos, which is synced to my stratum one over Ethernet, with a few pool servers added, has offset=-1.213 ms, with rootdelay=0.171 ms and rootdispersion=21.345 ms, which is a synch distance of 21.4305 ms, which is also its reported accuracy (maximum error). My other stratum two (Windows XP box) has offset=-1.529 ms, with rootdelay=0.150 ms and rootdispersion=6.131 ms, so it's synch distance=6.206 ms. So the accuracy goes down quite a bit once you introduce Ethernet and the internet. You can also use 'ntptrace' to report synch distance, if you don't want to do the math. It reports the values in seconds, however: saturn:$ ntptrace awk.xs4all.nl awk.xs4all.nl: stratum 2, offset -0.000939, synch distance 0.060813 Time1.Stupi.SE: stratum 1, offset 0.000000, synch distance 0.001197, refid 'PPS' -- Dennis Hilberg, Jr. [EMAIL PROTECTED] NTP Server Information: http://saturn.dennishilberg.com/ntp.php _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
