Interoperability Issues in Optical Transport Networks

Integrating transponders enabling higher capacity and implementing the latest transmission technologies is a frequent process in the life-cycle of operational optical network in order to respond to the continuous traffic growth. Therefore, moving towards interoperable and open transponders is a priority target of operators in order to replace the mono-vendor supplying model by a more competitive multi-vendor model and, in consequence, reduce the infrastructure cost. This process, commonly called "alien wavelength" support, requires that the network management software be able not only to control the multi-vendor transponders, but also estimate lightpath performance. Standard sets of parameters and protocol extensions enable the use of vendor-agnostic open-source tools, avoiding vendor lock-in. This paper describes different interoperable solutions and discusses their efficiency based on a comprehensive set of criteria related to the complexity of deployment, applicability to legacy equipment, cost and level of openness and interoperability.