On 27/08/2013 09:27, The Natural Philosopher wrote:
On 27/08/13 08:41, dennis@home wrote:


Just because the link to the ISP is over ATM doesn't mean subscribers
ATM circuits are presented at the ISP end.
They could be delivered via ethernet

Indeed they could, But I dont think they are in fact.

not unless you are on 21CN arrangement.


Even before that the ISP had a choice of pipes into the BT network.
there were cost advantages to some of them for some ISPs.

BT routes no packet at the IP level at all for 'customer ISPs'
You can tell that with a traceroute.

Next hop is always somewhere in the ISPs 'virtual' machine room./


And?

so the concept of association of IP with a distinct geographical area
simply does not exist.



That is up to the ISP and what they want to do with their IP addresses,
it has nothing to do with the BT network.