Evolution of Intelligent Transportation Systems (ITS) towards connected and autonomous vehicles requires robust communication protocols with proven or at least verified properties. In a recent work, we pointed out the advantages and limitations of both formal and simulation approaches when they are used separately during the design and evaluation processes of communication protocols dedicated to ITS. Our goal is to develop new tools combining formal methods such as Event-B with simulation formalism such as DEVS (Discrete Event System Specification) for proving and verifying the properties of ITS components models in large-scale scenarios. Previously, we presented the simulation models of a Vehicular Ad hoc Network (VANET) in a DEVS-based environment, where the Optimized Link State Routing (OLSR) protocol was used with a recently proposed clustering scheme, namely Chain-Branch-Leaf (CBL). Pursuing our objectives, this paper presents an equivalent model realized with Rodin, a formal tool based on a variant of the B method: Event-B. It shows how the specific properties of CBL clustering scheme are introduced in an Event-B model of OLSR from the literature, and how the numerous resulting proof obligations are discharged using the B prover in Rodin.