Measurement taxonomy[LA99]
Tup & Tdown: Fluctuations in the reachability for a given prefix. An announced route is withdrawn and transitions down ( Tdown ), or a currently unreachable prefix is announced as reachable and transitions up ( Tup ).
WWDup: The repeated transmission of BGP withdrawals for a prefix that is currently unreachable.
AADup: A route is implicitly withdrawn and replaced with a duplicate of the original route. [ ... ] a duplicate route does not differ in any BGP path attribute information.
AADiff: A route is implicitly withdrawn and replaced by an alternative route as the original route becomes unreachable, or a preferred alternative path becomes available
Flap: Tdown followed by Tup where the prefix has identical attributes when first announced and then re-announced after a withdrawal.