[ntp:questions] FreeBSD refclock error

David Newman dnewman at networktest.com
Thu Aug 16 16:40:54 UTC 2007


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On 8/14/07 3:15 PM, Kevin Oberman wrote:
>> Date: Tue, 14 Aug 2007 14:05:40 -0700
>> From: David Newman <dnewman at networktest.com>
>> Sender: questions-bounces+oberman=es.net at lists.ntp.org
>>
>>
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>> On 8/14/07 5:51 AM, Jason Rabel wrote:
>>>> ACK, thanks also for these tips.
>>>>
>>>> Next newbie question: Is ".GPS." the correct refid I should see?
>>>>
>>>> lancelot# ntpq -p
>>>> remote      refid      st t when poll reach   delay   offset jitter
>>>> =====================================================================
>>>> *time.domain.tld .GPS.  1 u   33   64  377    0.746  -40.803 20.547
>>>>
>>> The 'refid', in this case 'GPS' is the source which time.domain.tld is
>>> synced to. If it was synced to another NTP server then it would list its IP
>>> there. You really should use more than one server to sync to... 4 is
>>> generally the recommended minimum.
>>>
>> Thanks. Yet more newbie questions:
>>
>> 1. Is it better to (a) list 4 sources on the box with the GPS receiver
>> attached and just one source on all client boxes that point to it for
>> ntp, or (b) list 4 servers on all boxes?
> 
> b) It's always best to have 3 (or more) servers for any box running ntp
> as it allows the detection of broken servers and helps retain stability
> in the event the stratum 1 server has a problem. 1 is a bad number as it
> is a single point of failure. 2 is a bad number as it provides no clear
> way of detecting who is wrong if the time starts drifting on one of the
> servers. 

OK, thanks.

Per your recommendations, ntp.conf on all my boxes now points to five
servers -- my GPS receiver and four open stratum 1 and stratum 2 servers
relatively close to me:

server 127.127.26.0
server timekeeper.isi.edu
server t1.timegps.net
server t2.timegps.net
server hydrogen.cert.ucr.edu iburst
server clock.develooper.com iburst

The output of "ntpq -p" on the box with the GPS receiver looks OK:

    remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
xGPS_HP(0)       .GPS.            0 l   55   64  177    0.000  947.056
 2.907
*timekeeper.isi. .GPS.            1 u  117   64  176   26.919   -2.160
25.069
+cpe-76-168-23-8 .GPS.            1 u   51   64   75   21.999   -3.844
 3.186
+cpe-76-169-239- .GPS.            1 u  120   64   76   19.677   -2.655
 3.555
+hydrogen.cert.u 216.218.254.202  2 u   49   64  177    7.859   -1.684
 4.095
+clock-a.develoo 132.163.4.103    2 u   50   64  177    9.083   -2.506
 9.672


But on the other boxes -- the ones that should just poll my GPS box
first -- the refid is bizarre:


     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
time.mydomain.tld 138.23.180.126   3 u  112  128    7    0.769   45.224
 31.257
 timekeeper.isi. .GPS.            1 u  108  128    7   34.215   94.274
24.356
 cpe-76-168-23-8 .GPS.            1 u  239   64   10   19.493   88.521
 0.002
 cpe-76-169-239- .GPS.            1 u  109   64    2   21.401   60.130
 0.002
*hydrogen.cert.u 216.218.254.202  2 u   30   64   17    8.426   80.725
22.621
+clock-a.develoo 132.163.4.103    2 u   25   64   17   10.277   57.008
26.606

"138.23.180.126" is hydrogen.cert.ucr.edu, the first stratum 2 server in
my ntp.conf list.

Why would my GPS receiver list the UCR server as its refid?

thanks

dn

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