Although substantial progress has been made in automatically verifying whether distributed routing configurations conform to certain requirements, diagnosing and repairing configuration errors remains manual and time-consuming. To fill this gap, we propose S^2Sim, a novel system for automatic routing configuration diagnosis and repair. Our key insight is that by selectively simulating variants of the given configuration in a symbolic way, we can find an intent-compliant variant, whose differences between the given configuration reveal the errors in the given configuration and suggest the patches. Building on this insight, we also design techniques to support complex scenarios (e.g., multiple protocol networks) and requirements (e.g., k-link failure tolerance). We implement a prototype of S^2Sim and evaluate its performance using networks of size O(10) ~ O(1000) with synthetic real-world configurations. Results show that S^2Sim diagnoses and repairs errors for 1) all WAN configurations within 10 s and 2) all DCN configurations within 20 minutes.

翻译：尽管在自动验证分布式路由配置是否符合特定要求方面已取得实质性进展，但配置错误的诊断与修复仍依赖于手动操作且耗时费力。为填补这一空白，我们提出了S^2Sim——一种用于自动路由配置诊断与修复的新型系统。我们的核心思路是：通过对给定配置的变体进行选择性符号模拟，能够找到一个符合设计意图的配置变体，该变体与原始配置之间的差异既能揭示原始配置中的错误，又能直接提示修补方案。基于这一思路，我们还设计了支持复杂场景（如多协议网络）和复杂需求（如k链路容错）的技术方案。我们实现了S^2Sim的原型系统，并使用具有合成现实配置的O(10)~O(1000)规模网络评估其性能。结果表明，S^2Sim能够在以下场景中完成错误诊断与修复：1）所有广域网配置在10秒内完成；2）所有数据中心网络配置在20分钟内完成。