ExampleCode
realistic big_pix small_router big_router1 big_router2 protect_web mngt
nat x y1  y2 z v
optimize paris rome cairo
any paris rome cairo
both-any paris rome cairo
ip-ranges paris rome cairo
interface-rules paris rome cairo
loop paris rome cairo gibraltar agadir

This topology is used for all but the first both examples.

But this is used for example loop.