A reconfigurable WDM add/drop multiplexer operative as an add/drop node on an optical fiber carrying a plurality of WDM signals, said add/drop multiplexer comprising: a coupler splitting said WDM signals on said optical fiber, said coupler having a coupler input terminal for connection to said optical fiber, and first and second coupler output terminals for said split WDM signals from said optical fiber; a demultiplexer element connected to said first coupler output terminal, said demultiplexer element separating said split WDM signals at a plurality of drop terminals; a wavelength-selective switch having a demultiplexer having a plurality of output terminals and an input terminal for connection to said second coupler output terminal, having a multiplexer having a plurality of input terminals and an output terminal for connection to said optical fiber, and a plurality of 2X1 switches, each connected to one of said demultiplexer output terminals, one of said multiplexer input terminals and one of a plurality of add terminals, each switch either connecting said one multiplexer input terminal to said one demultiplexer output terminal or to one of said plurality of add terminals in response to control signals, whereby said wavelength-selective switch selectively adds WDM signals on said plurality of add terminals responsive to said control signals; and a first monitoring point at said wavelength-selective switch demultiplexer input terminal, a second monitoring point at said wavelength-selective switch multiplexer output terminal, a plurality of third monitoring points, each third monitoring point between each 2X1 switch and its connected wavelength-selective switch multiplexer input terminal, and a plurality of fourth monitoring points, each fourth monitoring point between each 2X1 switch and its connected add terminal. a coupler splitting said WDM signals on said optical fiber, said coupler having a coupler input terminal for connection to said optical fiber, and first and second coupler output terminals for said split WDM signals from said optical fiber; a demultiplexer element connected to said first coupler output terminal, said demultiplexer element separating said split WDM signals at a plurality of drop terminals; a wavelength-selective switch having a demultiplexer having a plurality of output terminals and an input terminal for connection to said second coupler output terminal, having a multiplexer having a plurality of input terminals and an output terminal for connection to said optical fiber, and a plurality of 2X1 switches, each connected to one of said demultiplexer output terminals, one of said multiplexer input terminals and one of a plurality of add terminals, each switch either connecting said one multiplexer input terminal to said one demultiplexer output terminal or to one of said plurality of add terminals in response to control signals, whereby said wavelength-selective switch selectively adds WDM signals on said plurality of add terminals responsive to said control signals; and a first monitoring point at said wavelength-selective switch demultiplexer input terminal, a second monitoring point at said wavelength-selective switch multiplexer output terminal, a plurality of third monitoring points, each third monitoring point between each 2X1 switch and its connected wavelength-selective switch multiplexer input terminal, and a plurality of fourth monitoring points, each fourth monitoring point between each 2X1 switch and its connected add terminal.