DWDM optical extension to the transport SDN controller

Transport networks are evolving to be more and more automated and driven by software to minimize the operational costs and to provide new services and applications in a quicker and more efficient way. The Software Defined Networking (SDN) approach is one of the major attempts in this direction. It decouples the network control plane from the forwarding plane and abstracts the underlying infrastructure to the applications and network services on top of the controller. But if one wants to extend the SDN approach to the physical, photonic layer, then the SDN controller must take the analogue nature of the optical transmission into account, in which the physical impairments of light paths in DWDM networks can limit which connections are doable. The problem of evaluating the feasibility of an optical connection becomes particularly difficult in case of mixed channel types and rates and where optical links with different properties have to be considered. In this paper we propose a procedure and suggest protocol extensions to capture, process and properly set power levels in these network scenarios. This procedure is mainly appropriate in dynamic scenarios, in which the opportunity to adjust the channel power levels on the fly could allow for the introduction of new optical traffic which would not otherwise be feasible, all the while ensuring that existing connectivity is not affected.