Ok, I have a layer 2 and and a layer 3 connection to a remote site. So the routing interface for the remote location is on a 6509, connected to another switch, then to the layer 2 cloud, then the remote switch. No good way to tell if layer 2 connection goes down. The backup route is 6509, then router, then t1 to the remote site. Lets say the layer 2 connection was down, and proxy arp was turned on the routers of the layer 3 connection. Would traffic then be "routed" via the layer 3 connection? as the arp request would be proxied over the t1, then answered and sent back.
I have this problem too.