[ntp:hackers] A stop-gap authenticated time service

Magnus Danielson magnus at rubidium.dyndns.org
Fri Nov 13 00:15:43 UTC 2015


Hi.

On 11/12/2015 08:46 AM, Poul-Henning Kamp wrote:
> --------
> In message <56439B35.3000103 at rubidium.dyndns.org>, Magnus Danielson writes:
>
>> Network "noise" breaks a bunch of assumptions, such as being stable.
>
> ...or even being "noise" rather than a signal.

Indeed.

Simple classical statistical values such as the mean and standard 
deviation can vary a lot over time. There is indeed some strong 
systematic components in these values at times, but completely 
independent strong shifts can occur whenever. Even the shape of the 
distribution shifts around.

It is even common to see people mistake the properties know from "a 
network" with that being the properties of any network. Similar to the 
non-converging noise-forms, it requires you to think again and put the 
classic statistics to the side for a moment. Saying that, using ADEV or 
TDEV on network noise is also not helpful, it's another mistake right 
there. That's where I think the Allan intercept method might not be 
completely useful in this case.

Cheers,
Magnus


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