[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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