Integration of Legacy Non-SDN Optical ROADMs in a Software Defined Network

Optical networks are well known for offering highrate bandwidth by sending data over light wavelengths. Such optical networks are composed of fiber optics, amplifiers, Reconfigurable Optical Add-Drop Multiplexers (ROADMs), etc. Nowadays, we wish to manage and monitor that type of network especially the ROADMs -- both flexibly and intelligently by integrating Software Defined Networking (SDN) into optical networks. Unfortunately, legacy ROADMs are not yet SDN compatible. While ROADMs have all the basic optical functionalities we wish to deploy (offered via Simple Network Management Protocol (SNMP) in our case), we are not always able to update their hardware or software to adapt legacy ROADMs to SDN architecture. The architecture proposed in this article -- a proxy that translates OpenFlow messages sent by the SDN controller (ONOS in our study) into SNMP messages to configure the ROADMs and vice versa, presents a solution. This solution allows us to not only flexibly monitor and manage an optical network via SDN architecture, but also to recover and reroute wavelengths when a link is down. It is also the solution most suitable for legacy networks because it does not require any upgrade to the optical network elements.