Model Checking Techniques for State Space Reduction in MANET Protocol Verification

A Mobile Ad hoc Network (MANET) is a network that consists of mobile nodes and is autonomously managed without infrastructure base stations such as access points. MANETs have started being used as part of safety critical applications. A Vehicular Ad hoc Network (VANET) used in automated driving systems is such an example. In such applications, defects in the network protocol may cause serious social problems. Model checking, a state search-based verification technique, has proven to be effective in finding faults in complex system designs, such as communication protocols. However it is challenging to apply this technique to MANET protocols, because a MANET can have a number of different network topologies, thus resulting in the state explosion problem very easily. In this paper we propose a modeling technique to mitigate this problem using the AODV protocol as a running example. MANET protocols, such as AODV, typically enforce a source node that wishes to establish a route to the destination to retry the route establishing process some fixed number of times in face of failures. We show that to model check the protocol's behavior in these retries it suffices to consider only the last trial. The results of preliminary experiments using the SPIN model checker show that using the proposed technique significantly reduced the time and memory used in model checking.