I have just spent the afternoon trying to get my head around this one and failed.
A customer has been set up with a new ADSL account with the following IP addresses: 88.x.a.116/30 (routed IP range) 88.x.b.170 (static IP).
I need to configure the router to everything to a firewall that'll route traffic accordingly.
I can't even work out from this configuration how many usable external IP addresses this will give them?
(I can get the router connected with the static IP in a normal configuration without problem.)
PS: God bless my Ubuntu Live CD, the tools you have to manage without on Windows!