The trustworthiness of modern networked services is too important to leave to chance. We need to design these services with specific properties in mind, and verify that the properties hold. In this paper, we argue that a compositional network architecture, based on a notion of layering where each layer is its own complete network customized for a specific purpose, is the only plausible approach to making network services verifiable. Realistic examples show how to use the architecture to reason about sophisticated network properties in a modular way. We also describe a prototype in which the basic structures of the architectural model are implemented in efficient P4 code for programmable data planes, then explain how this scaffolding fits into an integrated process of specification, code generation, implementation of additional network functions, and automated verification.
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