Refining Specifications for Configuration Repair with Side Effect Diagnosis

Writing specifications in configuration repair has become hard for network operators due to the increasing complexity of routing policies. If operators fail to describe critical routing policies in the specifications, the repair tools could introduce unexpected changes in routing behaviors (i.e., side effects) that violate the policies. To ease the operational burden of specification writing, we explore a specification refinement approach that (1) identifies such side effects by repair and (2) refines the specifications to prevent the side effects, rather than requiring operators to write the complete specifications from scratch. To realize this approach with existing repair tools, we propose SEA, a system that can diagnose the side effects by repair. By designing the refinement process using an existing repair tool and SEA, we first demonstrate how SEA helps operators write the specifications to prevent side effects. Second, we show that SEA completes the side effect diagnosis within ten seconds for various numbers of synthetic configuration changes on real network topologies.