BGP fall-over is a neat BGP convergence optimisation technique whereby BGP peering is brought down as soon as the route to neighbor disappears from a routing table. The difference between external and internal BGP is that the former usually peers over a directly-attached interface so that when the interface to neighbor is disconnected, route is withdrawn from the routing table which triggers eBGP fall-over to bring down the neighborship. iBGP, on the other hand, normally uses device loopbacks...
