[sclug] Potential in-bound routing failure on BT: any thoughts welcomed

[Keith Edmunds]

On Sun, 7 Apr 2013 20:09:41 +0100, sclug at neilzone.co.uk said:

> Before I try to escalate *again*, can anyone spot anything obvious I am
> failing to check here? 

Well, if you choose to use BT as your ISP... Seriously, I wouldn't. In my
experience, the smaller ISPs are way, way better. I'm now with Andrews and
Arnold, and would recommend them (they're not as expensive as I thought
they would be, and they are good).

But you want to fix your problem. You say your router is showing an IP
address of 100.x.x.x - is it 100, or 10? The latter is an RFC1918 address
(http://tools.ietf.org/html/rfc1918), which is not routable over the
Internet and would therefore imply CG-NAT. A quick Google for 'bt cg-nat'
suggests that BT do use it in places (which only underlines the stupidity
of BT, but I digress).

I suggest you ask BT if they are using CG-NAT. It's unlikely that you'll
get a straight answer first time, though. I would also do a 'whois' on the
IP address you have (the 100 one) to find out if it is a BT address. Then
I would ping from another connection (work or, if you can't do that, PM me
and I'll ping it) to see if it is routable from the Internet.

That may help. What may help much more is changing ISPs.
-- 
"You can't live a perfect day without doing something for someone 
who will never be able to repay you."