All-optical WDM networks are characterised by multiple metrics (hop-count, cost, delay, available bandwidth, loss probability, reliability), but generally routing algorithms only optimise one metric. Having in mind the inherent limitations of this type of approach, it seems potentially advantageous in the development of multicriteria models capable of explicitly representing the different performance objectives and enabling to treat in a consistent manner the trade off among the various criteria. A bicriteria model for obtaining a topological path (unidirectional or symmetric bidirectional) for each lightpath request in a WDM network is proposed. The first criterion is related to bandwidth usage in the links (or arcs) of the network. The second criterion is the number of links (hops) of the path. The model resolution approach uses a k-shortest path algorithm as well as preference thresholds defined in the objective function space, combined with a Chebyshev distance to a reference point (which changes with the analysed preference region). The solution of this bicriteria model is a non-dominated topological path. A heuristic procedure is then used to assign wavelengths to the links. The performance of the bicriteria model is analysed by comparing it with two monocriterion approaches, using two test networks.