"This paper describes photonic network technologies from the viewpoint of optical switching functionality and photonic network transparency； and presents an analysis of the various types of current photonic nodes. The analysis results show that the most important choice is whether or not the photonic network node system is constructed in an optically transparent manner. This paper also describes various types of photonic node architecture. Regarding the optical add drop multiplexing (OADM) system； the merits of the reconfigurable OADM (ROADM) are precisely analyzed."