[ntp:questions] Odd (mis)behavior when reference clock fails

Steve Kostecke kostecke at ntp.org
Tue Sep 23 19:21:10 UTC 2008


On 2008-09-23, Kevin Oberman <oberman at es.net> wrote:

>"Steve Kostecke" <kostecke at ntp.org> wrote:
>
>> On 2008-09-23, Kevin Oberman <oberman at es.net> wrote:
>>
>> > [---=| Quote block shrinked by t-prot: 40 lines snipped |=---]
>> >
>> >> It would be helpful to know the exact NTP version, and which
>> >> hardware clock and refclock driver was used.
>> >
>> > It's 4.2.4p4 running on FreeBSD 7.0. The reference clock is a
>> > EndRun Tech CDMA clock using the TrueTime driver. When the system
>> > was running, ntpq claimed no successful polls of the reference
>> > clock or the PPS. It was getting good responses from other systems,
>> > but not syncing to them.
>>
>> The ntpq peer billboard you posted shows that ntpd _has_ chosen
>> another system as the sys_peer. See below.
>
> Yes, that is quite clear.

The sys_peer is the time source that this ntpd is "synced" to.

>> >    remote       refid st t when poll reach  delay  offset jitter
>> >=================================================================
>> >TRUETIME(1)      .CDMA. 0 l    -   16    0   0.000   0.000  0.001
>> >PPS(1)           .PPS.  0 l    -   16    0   0.000   0.000  0.001
>> >-time1-owamp.es. .PPS.  1 u   17   64  177   2.058 -10.335  0.038
>> >*time2-owamp.es. .PPS.  1 u   49   64  177  24.556 -10.408  0.020
>> >-time3-owamp.es. .PPS.  1 u   63   64  176  55.640 -10.337  0.049
>> >+time4-owamp.es. .PPS.  1 u   59   64  176  20.770 -10.405  0.058
>> 
>> Is there something about this system which is different from the other
>> time servers?
>
> As stated, all of the servers are identical in terms of hardware and
> software and configuration. The only differences in the ntp.conf is that
> each system is missing the entry for itself.

It is possible that there may a problem with this hardware. Does the
clock always drift in the same direction? Do you see periodic clock
steps? You may need to adjust the kernel's tick.

-- 
Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/




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