So.. follow me here.
I'm on Host A which is connected to Router A. Router A connects to Router B which connects to Router C which connects to Switch A.
Pinging from Host A to Router C is successful, but pinging from Host A to Switch A is not possible.. and vice versa.. everything gets dropped at Router C.
Now, I've tried different MAC Addresses on the source NIC. I've cleared arp etc and I've checked the ACL on Router C and nothing. OSPF is running.
Any clue? My boss says I get a free day off if I figure this out. :)