Graph Grammar Modeling and Verification of Ad Hoc Routing Protocols

We present a technique for modeling and automatic verification of network protocols, based on graph transformation. It is suitable for protocols with a potentially unbounded number of nodes, in which the structure and topology of the network is a central aspect, such as routing protocols for ad hoc networks. Safety properties are specified as a set of undesirable global configurations. We verify that there is no undesirable configuration which is reachable from an initial configuration, by means of symbolic backward reachability analysis. In general, the reachability problem is undecidable. We implement the technique in a graph grammar analysis tool, and automatically verify several interesting non-trivial examples. Notably, we prove loop freedom for the DYMO ad hoc routing protocol. DYMO is currently on the IETF standards track, to potentially become an Internet standard. Updated March 2008. Extended abstract to appear in proc. 14th Int. Conf. on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2008).