GMPLS protocol was designed in order to apply label-switching techniques to different network technologies, such as time division multiplexing (TDM), wavelength routing and packet switching networks. Resource reservations are performed all along label switched paths (LSP). This paper proposes a novel constraint-based routing (CBR) algorithm for GMPLS networks. Our solution includes path computation and resourcespsila assignment for both admission control and failure recovery mechanisms. Unlike other constraint-based routing protocols, our algorithm supports several classes of traffic with different failure recovery schemes. We investigated the performance of our algorithm through simulation works which are performed on a GMPLS optical network configured with the European reference core topology. Numerical results have shown that, compared to constrained shortest path first (CSPF) routing, our solution enhances the success probability of path setup and optimizes the global performance in terms of queuing delay and bit loss ratio