[ntp:questions] Re: ref clock for network POP locations

Richard B. Gilbert rgilbert88 at comcast.net
Thu Sep 28 12:30:19 UTC 2006


Heiko Gerstung wrote:

> Jeff W. Boote schrieb:
> 
>> I have some network locations where I have no way to access GPS or 
>> CDMA. But, I would still like to have a very accurate time source. (I 
>> would like sub-microsecond accuracy from NTPD if I can get it.) These 
>> locations are in telco-hotels, so they are typically very well 
>> shielded making any broadcast technology unworkable. (We are not using 
>> sonet - so getting time from there is also not an option.)
<snip>
> Hi Jeff,
> 
> as already mentioned, sub-microsecond accuracy is not a possibility with 
> NTP these days. Did you check out PTP (IEEE 1588) instead 
> (ieee1588.nist.gov)?
> 

That is not true.  You can get microsecond accuracy or better using a 
reference clock.  What you can't do is get that kind of accuracy over 
the internet.

My only knowledge of PTP is based on some earlier messages here but I 
believe that it must have the same problems as NTP over the internet.

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