Crosstalk is an important limiting factor on the scalability of dense wavelength division multiplexing (DWDM) netwoks. Crosstalk contributions in three types of DWDM cross-connect topologies with dilated Benes switch architecture have been identified. Results show that first-order crosstalk can be removed in the three optical cross-connect (OXC) nodes and the second-order crosstalk can be eliminated with narrow-band tunable optical filter introduced in the second scheme. Scalability of intensity-modulation direct-detection DWDM networks which built with the three OXC nodes is compared and discussed by numerical simulation. Results indicate that dilated Benes switch-based OXC nodes have good scalability although they are built with high crosstalk-level component. Although the crosstalk of the optical devices used in OXC node is large, it can be reduced by carefully designing the OXC node topology.