Loop freedom of the (untimed) AODV routing protocol

The Ad hoc On-demand Distance Vector (AODV) routing protocol [6] allows the nodes in a Mobile Ad hoc Network (MANET) or a Wireless Mesh Network (WMN) to know where to forward data packets. Such a protocol is ‘loop free’ if it never leads to routing decisions that forward packets in circles. This development mechanises an existing pen-and-paper proof of loop freedom of AODV [4]. The protocol is modelled in the Algebra of Wireless Networks (AWN), which is the subject of an earlier paper [3] and mechanization [1]. The proof relies on a novel compositional approach for lifting invariants to networks of nodes. We exploit the mechanization to analyse several variants of AODV and show that Isabelle/HOL can re-establish most proof obligations automatically and identify exactly the steps that are no longer valid. Each of the variants is essentially a modified copy of the main development. Further documentation is available in [2].