Key Challenge: Specification


Three types of constraints to express.
Pattern-based: artifacts of today's configuation languages
Control-flow: interaction with routing at lower "scopes" (e.g., IGP) 
Information-flow: interaction with other participants in the same "scope" (i.e., other ASes)
We are developing a tool that checks 
these types of constraints.

High-level configuration depends on specification.
Verification also requires a specification of intent,
which can inspire configuration language design.