In this paper, the novel Fog Communications and Computing paradigm is addressed by presenting an integrated system architecture, that is applied to achieve a full con- text awareness for vehicular networks and, consequently, to react on traffic anomalous conditions. In particular, we propose to adopt a specific co-designed approach involving Application and Networks Layers. For the latter one, as no infrastructure usually exists, effective routing protocols are needed to guarantee a certain level of reliability of the in- formation collected from individual vehicles. As a consequence, we investigated classical Epidemic Flooding based, Network Coding inspired and Chord protocols. Besides, we resort to Blockchain principle to design a distributed consensus sensing application. The system has been tested by resorting to OMNeT++ framework for its modularity, high fidelity and flexibility. Performance analysis has been conducted over realistic scenarios in terms of consensus making overhead, latency and scalability, pointing out the better trade-off allowing the overlay P2P network formation and the complete context awareness achieved by the vehicles community.