The wavelength division multiplexing network design problem is considered in this paper. The literature is replete with prescriptive integer programming models for various versions of WDM network design problems, but in no case they consider the real situation of solving them taking into account the former nature of the problem, that is, its inherent vagueness. In this paper, this vagueness is assumed and handled by means of fuzzy sets based methodologies. In particular, two Fuzzy Integer Linear Programming models are proposed to be used as auxiliary models for solving the former problem. As an original way to effectively solve this models obtaining cost-effective network designs, we us