[ntp:questions] Laptop

Danny Mayer mayer at ntp.isc.org
Tue Mar 14 13:18:48 UTC 2006


Gerriet M. Denkmann wrote:
> 
> On 13 Mar 2006, at 08:50, Danny Mayer wrote:
> 
>> Gerriet M. Denkmann wrote:
>>> ntpd seems to require a constant internet connection (although as far
>>> as  I can see this is never explicitly stated).
>>>
>>> But what about a computer, which is only occasionally (on average once a
>>> day) connected to the internet, and for a few minutes (5 minutes on
>>> average)?
>>>
>>
>> ntpd was designed at a time that Internet access was unreliable and you
>> would be dialing the NIST number in Colorado, US, to get an accurate
>> time source. So yes, this is actually normal.
>>
>>> Can ntpd be used in this case?
>>
>> Yes.
>>
>>> If yes, what paramters have to be set in ntp.conf?
>>
>> Set up your server with iburst options and don't use any restrict lines.
>> in the startup line add -g which will allow it to reset you clock even
>> if the clock is way off.
>>
>>> If no, are there any programs available to handle this?
>>>
>>
>> ntpd works fine. Just restart ntpd every time you connect as the IP
>> address of your local system will change and ntpd does not yet handle
>> dynamic address changes on the local machine.
> 
> This is what I currently do.
> 
> But the man page says: "After one hour the frequency file is created and
> the current frequency offset written to it." 
> And: "It may take some hours for the frequency and offset to settle down."
> 
> As the laptop is almost never connected to the internet for 1 hour, the
> drift file exists, but just contains 0.00.
> 
> And so every day, when the computer connects to the internet and ntpd is
> started, the clock jumps back by 2.2 seconds.
> 
> I would much prefer a more continous operation.
> 

Someone had supplied a patch to change the default drift file write
frequency to a configurable value. This sounds like just what you need
for your case.

I'll have to look to see where that stands.

Danny

> Gerriet.
> 




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