Symptom
BGP session brought down by hold timer expiry instead of lost route to peer when fall-over is configured
Conditions
Only happens when a static route is configured to the neighbor through an interface, a Null0 static route is configured in the same subnet, and the interface is taken down
Workaround
Avoid using static routes with Null0 interface in the same subnet as a BGP neighbor configured to a specific interface if fall-over is configured.
Usage of a static Null0 route in the same subnet as a BGP neighbor that is NOT configured to a specific interface will work with fall-over as expected.
Example:
Prefer:
ip route 10.10.10.0 255.255.255.252 Null0 254
ip route 10.10.10.2 255.255.255.255 10.10.10.2
Instead of:
ip route 10.10.10.0 255.255.255.252 Null0 254
ip route 10.10.10.2 255.255.255.255 Ethernet0/0 10.10.10.2
Further Problem Description
This issue does not affect recursive static routes (i.e. physical interface not specified)
