The NG WDM two-dimensional ROADM site can use the WSMD9 single board, and its signal flow is the optical signal connected to the main optical channel from the "IN" optical port. Through the RDU (ROADM Demix Unit) optical module broadcast into 9 channels of the same optical signal; respectively output from the "DM1~DM8" and "ECPO" optical ports. One of the signals is dropped locally by the splitter board, and the other 8 signals are dispatched to the other 8 directions. From the "EXPI" optical port to access the signals of each wave of the main optical channel. The multiplexed or single-wavelength optical signals that need to be added locally are input through the "AM1"~"AM8" optical ports.