In computer networking and telecommunications, route flapping occurs when a router alternately advertises a destination network via one route then another, or as unavailable and then available again, in quick sequence.
within the network which cause certain reachability information to be repeatedly advertised and withdrawn.
For example, link flap occurs when an interface on a router has a hardware failure that causes the router to announce it alternately as up and down.
In networks with link-state routing protocols, route flapping will force frequent recalculation of the topology by all participating routers.
In both cases, it prevents the network from converging.