Yes, it is required to prevent route flapping.
On Wed, 9 Jul 1997, Jon Lewis wrote:
> > Well, Livingston is working a specialized version of this for
> > dynamic address pools. Unfortunately, it will not have the flexibility of
> > the null interface idea.
>
> The null0 interface seems a much better idea. Does the PM3 actually not
> support this idea? I'd think it would be a requirement (to prevent
> route flapping) if you're going to bgp export routes, wouldn't you want
> to do something like:
>
> add route 205.229.48.0/20 null0 255
> add route 208.215.0.0/20 null0 255
>
> and then BGP export only certain ones of your connected routes?