Optimized Deployment and Routing Strategies for QKD and DWDM Networks

Quantum key distribution (QKD) is an emerging technique for encrypting dense wavelength-division multiplexing networks (DWDMNs). The network-wide utilization of QKD raises challenges for deploying a QKD network (QKDN) and operating it via the key management network (KMN). These challenges include the optimized placement of QKD devices and the utilization of the QKDN. The goal of our QKDN deployment strategies is to maximize the reuse of infrastructure of the DWDMN, and the routing algorithms focus on the most efficient use of the deployed QKDN. We evaluate the multi-layer network consisting of a QKDN, a KMN, and a DWDMN and jointly optimize operation and deployment. Our analysis comprises different routing algorithms for key relaying within the KMN. Furthermore, we compare different deployment strategies for QKDNs and investigate the joint impact of both network layers, the QKDN, and the key management layer. For the two analyzed scenarios of uniformly distributed demands and the multi-year planning scenario, we can reduce the number of required QKD devices by approx. 11 % to 18 % without any performance penalty through optimized utilization of the deployed QKDN as compared to suboptimal operation. Finally, we show the combination of deployment and key relay algorithms that can cope with a multi-period traffic demand forecast. In the analysis of the multi-year planning scenario, we demonstrate deployment strategies that scale with the increasing demands of the DWDMN in the future, maintain optimized utilization, and, hence, allow efficient future-proof quantum-safe communication.