Kipton Moravec wrote: > I have two Ubuntu computers. A server (Blue) and a workstation (red). > > I thought I would set up Blue as a NTP server, and have red get time > from it and the pool. > > Blue says its time is good, but red says blue is an outlier. > > Blue is a 3.0 GHz Pentium, with 512M RAM and not doing anything else at > the moment (not even file serving). They are connected together with an > 8 port switch. So there is no distance between them. > > Here is Blue: > > [EMAIL PROTECTED]:~$ ntpq -p > remote refid st t when poll reach delay offset > jitter > ============================================================================== > +europium.canoni 192.36.133.17 2 u 507 1024 377 116.412 3.837 > 1.207 > -server1-a.your. 64.202.112.75 2 u 526 1024 377 32.929 6.629 > 0.734 > +ntp1.us.grundcl 164.67.62.212 2 u 443 1024 377 46.272 3.858 > 0.653 > -ntp.LogicX.net 18.103.0.198 2 u 266 1024 375 55.304 -1.035 > 0.644 > *time.nist.gov .ACTS. 1 u 478 1024 377 32.773 2.198 > 0.201 > -ntp3.tamu.edu 128.194.254.7 3 u 414 1024 377 46.361 13.276 > 1.496 > > [EMAIL PROTECTED]:~$ ntptrace > localhost: stratum 2, offset 0.002716, synch distance 0.041578 > time.nist.gov: stratum 1, offset 0.000000, synch distance 0.002650, > refid 'ACTS' > [EMAIL PROTECTED]:~$ > > Here is red: > > [EMAIL PROTECTED]:~ $ ntpq -p > remote refid st t when poll reach delay offset > jitter > ============================================================================== > +europium.canoni 192.36.133.17 2 u 91 1024 377 116.228 3.783 > 0.903 > -Blue 192.43.244.18 2 u 72 1024 377 0.144 -0.415 > 2.072 > *darkcity.cerias .GPS. 1 u 315 1024 377 56.111 3.591 > 11.436 > -tesla.fireduck. 198.82.1.201 3 u 122 1024 377 53.209 -2.050 > 0.208 > -clock.trit.net 192.12.19.20 2 u 108 1024 377 43.304 -10.235 > 0.827 > +server.donkeyfl 18.26.4.105 2 u 125 1024 377 56.097 5.461 > 0.514 > > [EMAIL PROTECTED]:~ $ ntptrace > localhost: stratum 2, offset 0.002221, synch distance 0.062901 > 128.10.252.7: timed out, nothing received > ***Request timed out > [EMAIL PROTECTED]:~ $ > > Why does red not use the data from Blue?
If you look at the offset readings, blue is among those that disagree more on the time, relative to the ones that disagree less. Blue is at -0.415, tesla is at -2.050, and clock is at -10.235. That's a wide variation compared to europium at 3.783, darkcity at 3.591, and server at 5.461. They agree much more closely, therefore they were chosen as the peer and candidates. If you want red to use blue exclusively, then add the 'prefer' option in red's ntp.conf. Example: server blues.ip iburst prefer > What would cause Blue to have so much jitter when they are so close > together? Do I have something set wrong? I get similar jitter (2.072) over Ethernet and through a router at maxpoll 10 (1024 sec. poll), it's just the nature of the beast. If you want red to follow blue closer, set the maxpoll lower. Since you're on a private network, minpoll 4 maxpoll 4 won't be a problem. For example, in red's ntp.conf: server blues.ip minpoll 4 maxpoll 4 iburst prefer This will clamp red's poll of blue at 16 sec. Red will follow blue as close as possible with this configuration. Let it run for a while a notice how low the offset and jitter gets. Whatever you do, don't use minpoll 4 maxpoll 4 on any public servers (this includes the pool), unless you've OKed it with the admin FIRST. > Kip Hope that helps, Dennis -- 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
