Intraband crosstalk contributions in three types of WDM cross-connect topologies based on the Benes architectures are identified. The crosstalk behaviours of the WDM networks are compared and discussed. It is demonstrated that the first-order crosstalk contributions are dominated by the crosstalk from the switching elements. The network scalability is analysed in terms of fibres, wavelengths and nodes. The results show that routing different wavelengths in each switching architecture in WDM cross-connect networks is a reasonable approach to achieve perfect performance in the presence of component crosstalk.