RNFD: Routing-Layer Detection of DODAG (Root) Node Failures in Low-Power Wireless Networks

While routing protocols for low-power wireless networks, such as CTP or RPL, handle link failures relatively well, node failures have received considerably less research attention. This paper thus studies crash-failures of destination nodes in distance-vector routing, that is, failures of so-called DODAG root nodes. First, it demonstrates empirically that handling root node crashes in existing state-of-the-art routing protocols leaves room for improvement or even fails completely in some cases. Second, based on an analysis of this behavior, the paper proposes RNFD, a new algorithm that explicitly tracks node failures at the routing layer. The algorithm is designed as a framework that complements rather than replaces regular route maintenance algorithms, which facilitates its integration with the existing protocols. Third, the paper evaluates a prototype implementation of RNFD through simulations and testbed experiments. In particular, it demonstrates that, with little information overhead, RNFD can speed up node failure detection by an order of magnitude and considerably reduce the traffic during the process.