Geo location to IP mapping

Marshall Eubanks tme at
Tue May 16 01:49:31 UTC 2006

I seriously doubt this would work to better than the regional area.

My zip code (20124) region is about 5 km across, which would be 15  
microseconds in vacuum, and
maybe at most 50 micro seconds in glass. So, you would need  
accuracies at the 10's of microsecond level to specify zip codes.

I can believe that you can measure transmission times down a fiber  
and achieve repeatability at the microsecond level - in fact, I  
remember a Michelson interferometer that they set up at JPL /  
Goldstone that tested
the Sagnac effect in glass, which required substantially better  
repeatibility than that.

But do you really think that you can estimate the router delay on the  
(for example) 9 hops between here and GMU
to better than 1 millisecond each ? (That would imply a 3 millisecond  
rms error if these errors were random and Gaussian, or about 1000 km  
in vacuum, and maybe 500 km error in glass.)

So, I think that this would fail by at least 2 orders of magnitude for
zip codes in a real operational network. Which coast of the US, sure,  
but not much better than that.


On May 15, 2006, at 5:24 PM, sgorman1 at wrote:

> The NSA was granted a patent for an IP geo-location technology  
> based on triangulation using latency measures.  We played around  
> with a similar approach using UDP several years ago and you could  
> triangulate to the zip code level or so.  A better way I think than  
> the current approaches being discussed.  Not sure if the NSA patent  
> is being commercialized or not though.
> 2100-7348_3-5875953.html

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