The Maelstrom: Network Service Debugging via "Ineffective Procedures"

The process of network debugging is commonly guided by ``decision trees,'' that describe and attempt to address the most common failure modes. We show that troubleshooting can be made more effective by converting decision trees into suites of ``convergent'' troubleshooting scripts that do not change network attributes unless these are out of compliance with accepted norms. ``Maelstrom'' is a tool for managing and coordinating execution of these scripts. Maelstrom exploits convergence of individual scripts to dynamically infer an appropriate execution order for the scripts. It accomplishes this in O(n²) procedure trials, where n is the number of troubleshooting scripts. This greatly eases adding scripts to a troubleshooting scheme, and thus makes it easier for people to cooperate in producing more exhaustive and effective troubleshooting schemes.