Optical communication systems have evolved from simple point-to-point transmission systems in the late 1970's to today's multi-channel DWDM systems integrated with optical switching. These advanced DWDM systems have very stringent optical performance, system reliability, and cost requirements. As a result, deployment of these systems has been limited to date. This situation has started to change recently and a lot of industry interest is now focused on deploying advanced optical systems in high performance telecommunication environments. Integrating optical functions in a single opto-electronic integrated circuit (OEIC) has the potential to accelerate this deployment by reducing manufactured costs, reducing physical card size, and increasing reliability. This paper will describe a specific instance of a DWDM transport and optical switching system, and its functional decomposition into individual cards. The requirements that are then imposed on the optical components placed on these cards are described. We will show the function of advanced switching and optical monitoring. Initial validation of a system card was made using off-the-shelf discrete optical components and then replaced with an OEIC implementation. Results of the integration experience will be presented.