NTP Server

Sun Oct 24 23:44:32 UTC 2010

On 10/24/2010 7:37 PM, Peter Lothberg wrote:
>> acquired the time from the three stratum-1 clocks, they all poll each other
>> for the average.
> 
> How many clocks/servers do you need to average from to knew that you
> are within say 1ms of UTC(nist)? 

What type of evidence model do you need to prove this with? - The NIST
servers located around the US are mostly operated out of people like our
operations (we have seven of them now and Atlanta coming online in about
three weeks as well.)

NTP has some foibles most are probably unaware of - that is it must have
three (3) competent sources defined so that it can vote. We like to also
say all three voices need to be coming from the same subnet so that the
network latency and other physical aspects which control the
policy-implementation are reliable as well.

If you take one server from multiple sites you will be stuck with
multiple network latency overhead factors polluting the resolution and
certainty in the 'small bits' of your time-attestation.

The real issue is how you prove the time-setting took. Or better yet -
that you allow Applications to make their own NTP queries of reference
time servers - that's really where the rubber meets the road in
time-centric trust models.

Todd Glassey

> 
> -P
> 
> 

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