Route flapping
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. == Condition == Route flapping is caused by pathological conditions (hardware errors, software errors, configuration errors, intermittent errors in communications links, unreliable connections, etc.) within the network which cause certain reachability information to be repeatedly advertised and withdrawn.