Wavelength‐transparent IP‐over‐CWDM network with stackable ROADMs for best effort performance

Stackable reconfigurable optical add/drop multiplexers (S‐ROADMs) have been proposed for use in IP over coarse wavelength‐division multiplexing (CWDM) networks so as to provide capabilities of remote lightpath reconfiguration and manual ROADM reconfiguration under the best effort transmission specified by the service level agreement. The S‐ROADM can be constructed by connecting modules with different wavelengths required in the node. The experimental results clarify that the S‐ROADM can add/drop or pass through the wavelengths successfully, providing no limit to the passing‐through (PT) wavelengths, that is, ensuring the wavelength transparency in the network. The S‐ROADMs could remove congestions by adding a lightpath remotely within a recovery time with degraded SLA. The transmission break time was also within the recovery time when adding a module manually to the in‐service S‐ROADM to increase bandwidth to be provided to new users. As a result, the S‐ROADMs provide more flexible CWDM networks in terms of scalability and reconfigurability.