> 
> Business class routers will ignore this but still let you use the origination IP (like the 100.1) as part of the routing table. My old Netgear, which I defaulted and left with my ex when we split, had that IP and I still got the outside IP on my firewall for routing. I could call up the firewall webpage at any time using the internal IP but it was never part of my network design.
> 

This feature right here cost me several hours last week. I had a Tomato
bridging to a D-Link standard firmware wireless. Replaced the D-Link wieh
another LInksys Tomato (to avoid massive crashes of the D-Link firmware).
When I did, I was hitting the bridge Tomato's IP while trying to get to
the Tomato that was its DHCP server. It drove me nuts until I realized
what was going on. Apparently my knowledge of TCP/IP network routing was
not as top-notch as I thought.

Here is your PSA: IF you have a router with its de facto firmware that can
take Tomato, swap to Tomato. Wow. Solid work they have done. I have been
using it since its beginnings.