Optical transport networks are evolving towards the support of dynamic setup/tear-down of services, demanding efficient accommodation of heterogeneous bandwidth requirements while minimizing capital and operational expenditures. Integrated OTN/DWDM networks can attain this objective by optimizing the utilization of traffic grooming and optical bypass at transit nodes. Moreover, the multiplexing of mixed lower order optical channel data units into a higher order data unit in a single stage enables to avoid bandwidth fragmentation, improving the wavelength channel utilization in these networks. This paper evaluates the blocking performance of an integrated OTN/DWDM network for different node and input traffic setups.