NetPiler: Detection of ineffective router configurations

Abstract—Configuring a network is a tedious and error-prone task. In particular, configuring routing policies for a network is complex as it involves subtle dependencies in multiple routers across the network. Misconfigurations are common and certain misconfigurations can bring the Internet down. In 2005, a misconfigured router in AS 9121 blackholed traffic for tens of thousands of networks in the Internet. This paper describes NetPiler, a system that detects router misconfigurations. NetPiler consists of a routing policy configuration model and a misconfig-uration detection algorithm. The model is applicable to routing policies configured on a single router as well as to network-wide configuration. Using the model, NetPiler detects configuration commands that do not influence the behavior of the network- we call these configurations ineffective commands. Although the ineffective commands could be benign, sometimes when the commands are mistakenly configured to be ineffective, they cause the network to misbehave deviating from the intended behavior. We have implemented NetPiler in approximately 128,000 lines of C++ code, and evaluated it on the configurations of four produc-tion networks. NetPiler discovers nearly a hundred ineffective commands. Some of these misconfigurations can result in loss of connectivity, access to protected networks, and financial implica-tions by providing free transit services. We believe NetPiler can help networks to significantly reduce misconfigurations. Index Terms—Network abstraction, network configuration modeling, network management, static analysis. I