(Optical Add-and-Drop Multiplexing) Method of branching off wavelengths from and/or inserting them into [CWDM] or [DWDM] lines. Included are Drop/Pass components diverting one or more colors out of the multiplexed wavelengths and let the rest of them pass, which enables bus-type infrastructure cabling. In addition, there are Drop-and-Insert components which extract single colors, and feed them in again. These are used for building e.g. redundant fiber optical backbone rings.