Geo location to IP mapping

Michael.Dillon at Michael.Dillon at
Tue May 16 09:26:27 UTC 2006

> I just tried that, says I'm 100 miles south of where I really am. That's 

> quite a long way out in a small country like England.

I live in London and use BT Broadband. But geolocation
shows me being in Ipswich up in East Anglia, a long
way from London. I assume this is because the geolocation
only knows that I use an IP address from a DHCP pool
managed in Ipswich. They don't know anything about 
BT's own extensive network, and in the case of DSL using
tunnels and DHCP servers, the real topology becomes
entirely invisible. The end result is that most of 
England's population lives in Ipswich. Eat your heart 
out Alan Partridge.

A few years ago, while working at a different company 
in London, I had a New York IP address because our company's 
internal network Internet gateway was in New York. Then
they changed things around so that we used a gateway in
London for all the European offices. But that meant that
colleagues in France, Germany, etc... would all show up
as being located in London.

Nowadays, I use a VPN to work from home. The VPN software
knows of multiple tunnel endpoint servers so if there is a 
problem with the UK server it fails over to a server in
the USA. My IP address on the Internet comes from the
NAT server at the Internet gateway. Depending on where the
tunnel endpoint is, it could be a US address or a UK address.

100% accurate geolocation is not achievable but if you
understand the issues then you can better make a decision
how to apply geolocation services to your own problem.
It may work well enough for some things. 
--Michael Dillon

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