Higher Level Reasoning about "Correctness" Validity: Does it advertise invalid routes? Bogus route injection, persistent forwarding loops, etc. Visibility: Does every valid path have a route? Session resets, missing sessions, damped routes, etc. Safety: Will it converge to a unique, stable answer? Policy-induced oscillation Determinism: Answer depend on orderings, etc.? Irrelevant route alternatives can affect outcomes. Information-flow control: Expose information? Accidental route leaks to neighbors, etc.