Thanks for the detailed reply. Jan Engelhardt wrote:
Your bridge sends a packet with a foreign address. So the ISP router will ask "arp who-has .34.99", and a client responds with ".34.99 at MAC macof3499". Then the router will send whatever IPv4 packet it wanted to send -- to macof3499, NOT to macofbridge.
I agree with the above statements. However, for my testing, I added a static arp entry of the foreign IP address (.34.99, from your example) with the MAC address of my bridge. So the packet should arrive at the bridge with the dest MAC set to the bridge's MAC address. It sounds like this should be enough to cause the packet to be sent back up the stack to my test code. But what I see is that my bridge ends up sending out arp requests for the foreign IP address (.34.9). So this is not the expected behaviour?
Hope this explains things a bit :-) Yes, your reply was very helpful. I'm off for a few days, but I'll pick this stuff back up again when I get back.
Thanks again for the information. Cam