Many high-bandwidth networks are currently being upgraded to include reconfigurable optical add/drop multiplexers (ROADMs) in order to improve efficiency and flexibility.
The ROADM mainly replaces the optical/electrical/optical (O-E-O) routers, and allows network operators to remotely change the amount of dropped or added wavelengths on the express route in order to optimize bandwidth; for example, not dropping wavelengths when bandwidth is not required.