North American Network Operators Group

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Re: Geo location to IP mapping

  • From: Roland Perry
  • Date: Tue May 16 07:04:36 2006

In article <[email protected]>, Bill Woodcock <[email protected]> writes
   > 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.

1.3ms is longer in small countries like England?
I'm virtually certain it's not being done by propagation delay.

What they've apparently done is look up the RIPE database, and found that my ISP has registered an address, with postcode, for the hostmaster function.

They've reported the major town associated with the two most significant (out of six) characters of that postcode (Hemel Hempstead), although the address is actually in a smaller town twenty miles to the west (Stoke Mandeville).

To complicate the issue, the ISP is formed by the acquisition of several smaller ISPs, and it seems unlikely (from my knowledge of the local topology) that the physical NOC is at the hostmaster's address.

Finally, the "tail" from the NOC to my house (which appears as one hop) is over a connection into British Telecom's ADSL backbone, and then over the BT internal network which supports their wholesale ADSL product, as far as my local telephone exchange (which I can see out of my office window) and a short length of local copper. There's nothing in either the RIPE database, or timing of packets, which could say where in the country that tail is delivered. The ISP has my billing address, of course.
Roland Perry