Currently, most optical add/drop multiplexer (OADM) systems deployed in metropolitan WDM networks are static, that is, a wavelength operating in different bands is used to add/drop a fixed wavelength group at the fixed node, while the remaining wavelengths are passed through. If service growth requires the wavelength capacity expansion or an adjustment at a node, you need to add a filter manually. Adding a filter results in insertion loss change and interrupted traffic transmission and affects the existing services. Reconfiguration optical add/drop multiplexing (ROADM) adjusts the wavelengths added or dropped at each node on the network in a quick and effective manner without affecting services, and saves the operation expenditure.