Lightpath reconfigurations in IP-over-CWDM networks with stackable ROADMs

Stackable ROADMs (S-ROADMs) have been proposed for use in regional IP-over-CWDM networks. The S-ROADM can be constructed by connecting modules with different wavelengths required in the node. The experimental results clarified that the S-ROADM could mux and demux the wavelengths successfully, and gave no limit to the passing-through wavelengths, making the network be wavelength transparent. Contrary to the S-ROADM, the existing fixed ROADMs were not wavelength transparent. The bidirectional S-ROADMs have also been proposed, and lightpaths could be reconfigured successfully in an IP-over-CWDM network with the bidirectional S-ROADMs.