I have an ADSL router (static IP) plugged into WAN1 configured as always on. A cable modem (static IP) into WAN2 configured as always on and WAN3 (SDSL static IP) configured as backup when ALL WAN fail.

WAN3 doesnt kick in unless I physically unplug WAN1 and WAN2. If WAN1 and WAN2 have no link (ie I unplug the external feeds but not the router connection to the 3200) then WAN3 remains off.

Is this intended behaviour of a "backup"? I.e. it will only backup a physical failure rather than a drop in connection? How can I configure the router to failover when WAN1 and WAN2 have no internet connectivity?

I have switched to PING instead of ARP which should cure it.