[ntp:questions] NTP on local networks

Richard B. Gilbert rgilbert88 at comcast.net
Thu Aug 2 15:13:01 UTC 2012


On 7/31/2012 12:06 PM, unruh wrote:
> One option is to install a gps receiver onto one or more of your
> machines to deliver accurate time to them.
>
> The second option is to look into "orphan" mode, which was designed for
> your situation.
>
> Your problem is probably that you are using more than one of th
> emachines as the "server" and they have gotten out of sync with each
> otehr so that the other machines cannot figure out which is the more
> accurate time. You give no indication of what you have set up so it is
> pretty hard to figure out what is going wrong.
>
> On 2012-07-30, Will Shackleford <shackle at nist.gov> wrote:
>>
>> We have several computers  with several different operating systems on a
>> local network with no radios and no internet connection.
>> The main goal is to keep them synchronized with each other.
>>
>> One frustration I have had is that clients tend to refuse to connect to
>> servers on the network
>> that are "not good enough". I assume "not good enough" means too high a
>> stratum although the
>
> stratum does not really matter (unless it is 15 or so) but disagreement
> amongst the servers does matter.
>
>> error messages are not that clear.
>
> Perhaps if you told us what they were, they would be clearer to some of
> us than to you.
>
>>
>> My current solution is to take a laptop to another room with an internet
>> connection, let it sit for an hour and
>> then bring it back to connect the local network where finally the other
>> computers will accept it and synchronize with it.
>>
>>
>> Questions:
>>
>> How can I configure a client/peer to always accept a server as "good
>> enough" or atleast always accept the server
>> when no other server can be contacted? (please answer for any platform
>> below you can)
>>
>>
>> Fedora 6:
>> Fedora 10:
>> Fedora 14:
>> Ubuntu 11.04:
>> Windows XP:
>>
>>
>> How can I configure a server to always consider itself "good enough" and
>> report that (lie if necessary) so that any badly configured
>> client will still connect?(please answer for any platform below you can)
>>
>>
>> Fedora 6:
>> Fedora 10:
>> Fedora 14:
>> Ubuntu 11.04:
>> Windows XP:
>>
>>
>>
>> Just for my own curiosity, why is just refusing to do what the operator
>> wants the default behavior for clients/peers? Why not always
>> synchronize as well as you can with whichever peers/hosts you can contact?

NTP needs a stable and accurate source of time.  Such sources are 
provided by most national governments.  In the U.S. the the National 
Bureau of Standards keeps the official clock for the U.S.  The official
time is supplied in Canada by an agency called Communications Branch, 
National Research Council.  Just about every country has it's own 
"standard" clock and they go to great lengths to ensure that all these 
clocks are accurate and stable.

How do you calibrate your atomic clock?  That's easy.  You load your 
clock into a truck with a battery pack and take your truck or your 
airplane and go to the National Bureau of Standards.  The staff bring a 
coaxial cable to your vehicle, connect it to your clock(s) input and 
zap!!!!  If you are really fanatical, you correct for the length of
the cable,  . . . .


Most of us don't go quite that far.  I, for instance, have a GPS timing 
receiver which keeps my computers marching to the same beat. It's 
overkill but I enjoyed  doing it.




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