Survivability of QKD Enabled Optical Network During Link Failure

Growing practicality and deployment of optical quantum key distribution (QKD) has renewed interest in information-theoretic secure (ITS) key exchange for future communication networks. Providing ITS keys as a service over existing optical network infrastructures is feasible, however it poses significant challenges, particularly due to limited access to large-scale QKD testbeds and the need to ensure reliability under network failures. To address this gap, this work presents a discrete-event QKD optical network simulator designed to study ITS key-as-a-service provisioning under fiber link failure conditions. The simulator integrates survivability and resource management concepts inspired by wavelength-division multiplexed optical networks. Using this framework, the performance of a time-slot key-rate-aware shared path protection (TSKRA-SPP) scheduling algorithm is evaluated in terms of throughput, failure tolerance, and quality of service (QoS). TSKRA-SPP provides high failure tolerance while keeping resource consumption significantly low compared to baseline Shared Path Protection (SPP) algoirthm. The results validates the proposed simulation framework to be an effective tool for analyzing resilient ITS key provisioning in QKD-enabled optical networks.