[Soekris] Soekris & NTP

[Bob Camp]

Hi

What's the topology of your network?

If you have asymmetric routing delays they can easily limit your  
accuracy.

We apparently  have some creative IT guys, so we even see non- 
stationary asymmetry on our LAN ....

Bob Camp


On Jun 20, 2007, at 9:05 PM, David Duchscher wrote:

> On Jun 20, 2007, at 2:59 PM, Poul-Henning Kamp wrote:
>
>> In message <38C0B262-97E1-4DDB-AAB3-B1A8CBEBADF3 at nostrum.com>,
>> David Duchscher
>> writes:
>>
>>> I am looking at using a Soekris unit for NTP and was wondering if
>>> people have a recommendation for which board to use?  Traffic  
>>> will be
>>> low, no encryption.  I was looking at the 4801 as I see netgate.com
>>> has a rack mount case for it but that is just a nicety and not
>>> requiredment.  GPS clock we are looking at using is the GPS 17HVS.
>>> Any comments, suggestions, pointers, etc would be greatly
>>> appreciated.
>>
>> Go for the 4501, you can get much better precision if you throw
>> a GPS and possibly a good X-tal after it.
>>
>> John wrote up my design here:
>>
>> 	http://www.febo.com/pages/soekris/
>
> That really is sweet.
>
> A couple of questions, if you have the time.  The accuracy requirement
> for our setup is +/- 1 millisecond, do you think the 4501 plus the
> Garmin GPS unit with the standard clock crystal would be able to
> meet that requirement?  The Garmin GPS 17HVS PPS line has a
> specification of +/- 1 microsecond.  Secondly, do you have an idea
> of what the accuracy of the such a setup would be?  It would be fun
> to build a very accurate NTP server but the requirements are not
> there. I am trying to keep things as simple and reliable as possible
> since I am not the only admin that will be maintaining the unit.
> At the same time, I rather not spend 400 for a Symmetricom NTS-150.
> As an example of our thinking, we decided on the Garmin GPS sensor
> for easy installation and it being designed for marine applications,
> would be able to handle the hot, long days of sun, and wet environment
> we have here.
>
> The Garmin manual is located here:
>
>    http://www8.garmin.com/manuals/GPS16HVS_TechnicalSpecifications.pdf
>
> Thanks for your time,
> --
> DaveD
>
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