Aggressive route flap dampening

  I believe the primary purpose of the /19 filtering was to reduce the
size of the route table. The increased stability this caused was just
a happy side affect.

This matches my memory.

I believe filtering predated the implementation of flap dampening
in IOS, but I could be wrong.

The idea of using very strict dampening as a means of accomplishing
the same goals as filtering was a later development, and came with
the expectation of crunchy routers being able to handle large stable
routing tables and distribute and process large amounts of NLRI in
reasonable amounts of time.