Conformance testing is crucial to the quality and reliability of routing protocols for pervasive communications. Most of the works are devoted to their simulations in order to study their performance in a simulated context without taking into account their formal requirements and specifications. Our work tackles the formal methods to test the conformance of a ad hoc routing protocol (i.e. OLSR) deployed in a real network. A passive testing technique is applied taking into account the OLSR formal specification, formal description of properties and collected traces of the implementation. This approach is complementary to active testing techniques allowing then to reduce the inconclusive verdicts often observed in several experiments