To take full advantage of SONET granularity and DWDM capacity, the two technologies must be combined to enable deployment of the most economic transport networks. The emergence of integrated SONET and DWDM platforms is also part of the effort to build a hybrid network to achieve this objective. It then poses a new challenge to network designers in designing networks mixed with MSPP, ROADM, and integrated platforms. This article provides guidelines on recognizing different types of hybrid networks and how to accomplish the design task by using existing design tools or procedures