— Many previously proposed routing metrics and algorithms for ad hoc networks work well in static networks, however, when nodes are moving and wireless links may fail from time to time, these routing metrics and algorithms are prone to poor performance. A cross-layer based routing protocol for mobile ad hoc networks, called Robust Link Availability Routing (RLAR) protocol, is proposed in this paper. RLAR consists of two modules, which estimates the link reliability using physical layer information and deals with robust optimal routing, respectively. Based on the optimal tree backbone, a mesh structure is formed for reliability enhancement. Through simulations, RLAR is proved to be able to increase the packet delivery ratio and reduce the frequency of reroutings for dynamic network topologies.