Quantum Key Distribution Network Architectures

Up to now, Quantum Key Distribution (QKD) Network architectures were confined to relatively small networks. Some theoretical and standardization work was carried out at the framework level but its real-world application is still to be proven. Here, we present a novel architecture for QKD Networks, which is based on the SDN approach, and the components needed to scale to large networks. A well-defined functionality of a minimal set of universal modules allows to define the flow of information among them, and this specifies their interfaces and the architecture. We show that this scheme allows to reuse many already proposed interface definitions requiring just minor adaptation and facilitating the real-world deployment. A QKD Network testbed demonstration following these principles is mentioned. We further elaborate on interfaces needed to scale to very large networks, enabling orchestrations of different types or network monitoring tools. The latter have not been considered in depth up to now, but are needed to support automation and advanced capabilities, multidomain networks, slicing, heterogeneity, resource discovery, etc., which will be necessary to scale to large networks. The dynamicity of the quantum level in this scheme allows a significant reduction of the need of QKD devices on the metropolitan scale, an increased robustness of the service, improving its quality and overall network management, showing that the presented architecture is highly appropriate for telecom operators.