BGP is Hard to Get Right


Routes from AS 1 have next-hop e.f.g.h
If e.f.g.h not injected into IGP, some routes from within AS will fail.

Correctness is more than shortest paths!
Federated, asynchronous operation ("coopetition")
Coupling with IGP
BGP's "correctness" is as much about configuration, policy, and competition as it is about pushing packets
How do we know if we've got it right?  What is "right"?