Chris
Dead Peer Detection is one of the functions performed by BGP. If the peer goes dead then BGP will detect it and will withdraw routes learned from that peer from the routing table.
What you describe about monitoring a public address is more about validating that the ISP routing logic is learning and advertising appropriate routes than it is about detecting if a peer has gone dead. I would think that this is possible - but a bit complex. I would think that you could configure IP SLA to track some public address (the tricky bit here is to make sure that you are tracking through ISP1 and not using ISP2 for this). Then you should be able to configure EEM to watch the track and if the route is lost to make appropriate changes in BGP to force the failover.
HTH
Rick
HTH
Rick
