static via ip

[Petr Šťastný]

  I'm not sure I understand how "static route via ip" works.

Users' docs says:

"When the particular destination is not available (the interface is down 
or the next hop of the route is not a neighbor at the moment), Static 
just uninstalls the route from the table it is connected to and adds it 
again as soon as the destination becomes adjacent again."

What is the meaning of word "neighbor" in this context?

protocol static defaultgw {
     route 0.0.0.0/0 via 192.168.1.20;
}

This static route will disappear from routing table when:
a) 192.168.1.20 is not reachable (no route to host, no entry in local 
routing table, router doesn't know how to reach it)
b) 192.168.1.20 is not a neighbor in any routing protocol at the moment 
(for example BGP session with 192.168.1.20 becomes down)

After some test, a) seems to be bird's behavior. But my first idea was 
that this static route should be active only if 192.168.1.20 is routing 
protocol neighbor and this protocol is running and active at the moment.

The goal is to shut down default route when BGP session with the BGP 
neighbor goes down. So b) would be better behavior for me.

The only way how to do this is to make a shell script that checks the 
status of BGP sessions a enables/disables static routes?