[ntp:questions] Odd behaviour in a multicast setting (bug in ntpd???)

Marco Marongiu brontolinux at gmail.com
Tue Aug 30 08:48:23 UTC 2011


Il 30/08/2011 10:35, Harlan Stenn ha scritto:
>> That could be. The point is: if I install a newer version on clients,
>> > I'll have to restart ntpd, and once I restart it, it will probably
>> > work (like all the other times we restarted them) and tell us nothing
>> > about the problem.
> It is interesting that the problem solves itself after a reboot.

Not actually a reboot, but a restart of ntpd.


> And it
> would be even more interesting to try at least one machine with a recent
> version of NTP to see if the problem repeats itself.

I'll check and see if I can use a backport for lenny.


> I did notice that the system that has the problem you mentioned with the
> host that does unicast is an outlier...

That's not always the case, e.g., on one machine it is currently a
candidate:

>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> +s51            69.25.96.13      2 m  283 1024  377    0.276    4.844   0.011
> +s11            128.9.176.30     2 m   41   64  377    0.203   -1.618   0.061
> *s12            204.123.2.5      2 m   56   64  376    0.001   -2.596   0.047
> -s52            204.9.54.119     2 m   22   64  376    0.001  -12.454   0.058
> 
> ind assID status  conf reach auth condition  last_event cnt
> ===========================================================
>   1 36023  7424    no   yes   ok   candidat   reachable  2
>   2 36024  7434    no   yes   ok   candidat   reachable  3
>   3 36027  7634    no   yes   ok   sys.peer   reachable  3
>   4 36028  7314    no   yes   ok    outlyer   reachable  1

and sometimes is even a peer:

> Aug 30 07:23:01 XXX ntpd[3989]: synchronized to <s51's address>, stratum 2

What you can notice, anyway, is that on those machines that show the
problem, the peer is "flapping" a lot:

> Aug 30 05:04:43 XXX ntpd[3989]: synchronized to <s51's address>, stratum 2
> Aug 30 05:10:39 XXX ntpd[3989]: synchronized to <s12's address>, stratum 2
> Aug 30 05:56:12 XXX ntpd[3989]: synchronized to <s51's address>, stratum 2
> Aug 30 06:05:21 XXX ntpd[3989]: synchronized to <s12's address>, stratum 2
> Aug 30 07:23:01 XXX ntpd[3989]: synchronized to <s51's address>, stratum 2
> Aug 30 07:44:32 XXX ntpd[3989]: synchronized to <s12's address>, stratum 2

Does this add any useful information?

Thanks

Ciao
-- Marco



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