Stimulus-response Reasoning


"What happens if I tweak this import policy?"
"Let's just readjust this IGP weight..."
"New customer attachment point? Some cut-and-paste will fix that!"

Some time later, some "strange behavior" appears.
(OOPS!  Revert.)

Operators have a terrible "programming environment".
Configuration is ad hoc and painful.
Wastes operator time. 
Suboptimal performance, angry customers. 

Can't check for errors by "seeing what happens".
Won't catch misconfigured filters, redundant route reflectors, etc.