Abstract In QKD‐enabled optical networks (QKD‐enabled ONs), fragmentation is one of the serious issues which can be mitigated through appropriate management of network resources. Thus, efficient allocation of network resources during routing and resource assignment is important to minimise the impact of time slot fragmentation in the quantum signal channel (QSCh) of QKD‐enabled ONs. The authors address the fragmentation problem in the QSCh and propose a new fragmentation‐suppressed routing and resource assignment (FS‐RRA) approach. To evaluate the performance and to analyse the effect of time slot fragmentation in QSCh of QKD‐enabled ONs, the proposed FS‐RRA approach is compared with two existing resource assignment approaches, namely, the first‐fit (FF) and random‐fit (RF) for two different networks. Simulation results show that the proposed approach reduces fragmentation by 2.97% and 6.69% for NSFNET and 1.77% and 5.91% for UBN24 in terms of external fragmentation compared to FF and RF, respectively. Furthermore, the proposed approach reduces blocking by 4.03% and 14.28% for NSFNET and 2.61% and 13.44% for UBN24 and improves resource utilisation up to 3.44% and 5.96% for NSFNET and 3.08% and 7.64% for UBN24 compared to FF and RF, respectively.
Abstract In QKD‐enabled optical networks (QKD‐enabled ONs), fragmentation is one of the serious issues which can be mitigated through appropriate management of network resources. Thus, efficient allocation of network resources during routing and resource assignment is important to minimise the impact of time slot fragmentation in the quantum signal channel (QSCh) of QKD‐enabled ONs. The authors address the fragmentation problem in the QSCh and propose a new fragmentation‐suppressed routing and resource assignment (FS‐RRA) approach. To evaluate the performance and to analyse the effect of time slot fragmentation in QSCh of QKD‐enabled ONs, the proposed FS‐RRA approach is compared with two existing resource assignment approaches, namely, the first‐fit (FF) and random‐fit (RF) for two different networks. Simulation results show that the proposed approach reduces fragmentation by 2.97% and 6.69% for NSFNET and 1.77% and 5.91% for UBN24 in terms of external fragmentation compared to FF and RF, respectively. Furthermore, the proposed approach reduces blocking by 4.03% and 14.28% for NSFNET and 2.61% and 13.44% for UBN24 and improves resource utilisation up to 3.44% and 5.96% for NSFNET and 3.08% and 7.64% for UBN24 compared to FF and RF, respectively.
Quantum key distribution (QKD) has potential of providing long-term security as it is based on the fundamental principles of quantum mechanics. Security of information transmitted through optical networks has attracted attention recently due to its vulnerability to attacks post quantum computers. Hence, the integration of QKD into optical networks can significantly improve the security of existing and future optical networks. In QKD-secured optical networks, the quantum channel and the classical channel are integrated into a single optical fiber to reduce the deployment cost of the network infrastructure. However, due to limited network resources in a single optical fiber, the efficient provisioning of network resources (wavelengths and time slots) and blocking are two major issues in such networks. In this work, a resource assignment strategy with scheduling, namely, resource assignment with scheduling (RA-WS) has been proposed for utilization of network resources efficiently. In the RA-WS strategy, the QKD lightpath requests (QLPRs) have been served according to the proposed scheduling criterion. Moreover, the proposed scheduling criterion for routing, wavelength and time-slot assignment (RWTA) can reduce the effect of QLPRs blocking because of the limited network resources. The performance of the proposed RA-WS strategy has been analyzed in terms of blocking probability (BP), success probability of update secret key (SPUSK), and time-slot utilization ratio (TSUR) with different reserved wavelengths for quantum signal channel (QSCh), i.e.,WQand different time slots (ntr). Simulations performed on NSFNET network topology indicate that the RA-WS strategy performs better than the baseline strategy, i.e., resource assignment without scheduling (RA-WOS) in terms of all the considered metrics.
Abstract In quantum key distribution‐secured optical networks (QKD‐ONs), constrained network resources limit the success probability of QKD lightpath requests (QLRs). Thus, the selection of an appropriate route and the efficient utilisation of network resources for establishment of QLRs are the essential and challenging problems. This work addresses the routing and resource assignment (RRA) problem in the quantum signal channel of QKD‐ONs. The RRA problem of QKD‐ONs is a complex decision making problem, where appropriate solutions depend on understanding the networking environment. Motivated by the recent advances in deep reinforcement learning (DRL) for complex problems and also because of its capability to learn directly from experiences, DRL is exploited to solve the RRA problem and a DRL‐based RRA scheme is proposed. The proposed scheme learns the optimal policy to select an appropriate route and assigns suitable network resources for establishment of QLRs by using deep neural networks. The performance of the proposed scheme is compared with the deep‐Q network (DQN) method and two baseline schemes, namely, first‐fit (FF) and random‐fit (RF) for two different networks, namely The National Science Foundation Network (NSFNET) and UBN24. Simulation results indicate that the proposed scheme reduces blocking by 7.19%, 10.11%, and 33.50% for NSFNET and 2.47%, 3.20%, and 19.60% for UBN24 and improves resource utilisation up to 3.40%, 4.33%, and 7.18% for NSFNET and 1.34%, 1.96%, and 6.44% for UBN24 as compared with DQN, FF, and RF, respectively.
Optical network security is attracting increasing research attention, as loss of confidentiality of data transferred through an optical network could impact a huge number of users and services. Data encryption is an effective way to enhance optical network security. In particular, QKD is being investigated as a secure mechanism to provide keys for data encryption at the endpoints of an optical network. In a QKD-enabled optical network, apart from TDChs, two additional channels, called QSChs and PIChs, are required to support secure key synchronization. How to allocate network resources to QSChs, PIChs, and TDChs is emerging as a novel problem for the design of a security-guaranteed optical network. This article addresses the resource allocation problem in optical networks secured by QKD. We first discuss a possible architecture for a QKD-enabled optical network, where an SDN controller is in charge of allocating the three types of channels (TDCh, QSCh, and PICh) over different wavelengths exploiting WDM. To save wavelength resources, we propose to adopt OTDM to allocate multiple QSChs and PIChs over the same wavelength. An RWTA algorithm is designed to allocate wavelength and time slot resources for the three types of channels. Different security levels are included in the RWTA algorithm by considering different key updating periods (i.e., the period after which the secure key between two endpoints has to be updated). Illustrative simulation results show the effects of different security-level configuration schemes on resource allocation.
Currently, with the continuous advancement of network and communication technology, the amount of data carried by the optical network is very huge. The security of high-speed and large-capacity information in optical networks has attracted more and more attention. Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics. Introducing QKD into an optical network can greatly improve the security of the optical network. In order to reduce the cost of deployment on QKD infrastructure, quantum signals in QKD and classical signals in optical networks are multiplexed in the same fiber by wavelength-division manner. Moreover, due to the limited wavelength resources in an optical fiber, time-division technology is adopted to construct different kinds of channels in QKD system for efficient utilization of wavelength resources. Under such situation, how to satisfy the security requirements of service requests and complete the efficient scheduling of multi-dimensional resources, i.e., wavelengths and timeslots, is a challenging problem. This paper addresses this problem by considering multi-dimensional routing, wavelength, and timeslot allocation (RWTA) in short-distance quantum key distribution optical networks (QKD-ON), in which any two nodes can directly establish a quantum channel, and the maximum distance between any two nodes is less than the distance that can carry out point-to-point quantum key distribution process. While accommodating services with security requirements in QKD optical networks, to avoid the wavelength time-slot fragmentation caused by the constraints of wavelength consistency and time-slot continuity, we propose a time-window-based security orchestration strategy as well as relative-loss of time continuous compactness based RWTA strategy. We conducted the simulations under various scenarios, e.g., different key updating periods and different distributions on wavelength resources, etc., and the results show that the proposed strategy can achieve better performance compared with the baselines in terms of key success rate, key-updating delay, and blocking probability.
Resource constraints in quantum key distribution-secured optical networks (QKD-ONs) frequently prevent successful quantum light-path request (QLR) fulfillment. This work introduces a routing and resource assignment (RRA) strategy prioritizing minimal transmission distance to address this limitation. The proposed scheme employs a metric evaluating fiber length to determine optimal quantum signal paths. By minimizing cumulative (photon) travel distance, the proposed approach improves resource efficiency. The proposed distance-aware deep reinforcement learning (DA-DRL) based scheme’s performance is evaluated against first-fit (FF) and random-fit (RF) methods, across two network topologies NSFNET and UBN24. Simulation results show that, for NSFNET, the proposed approach scheme reduces blocking by 6.18% and 9.18% and for UBN24, by 2.71% and 3.41%, when compared to FF and RF respectively.
Abstract Quantum key distribution (QKD) optical networks can provide more secure communications. However, with the increase of the QKD path requests and key updates, network blocking problems will become severe. The blocking problems in the network can become more severe because each fiber link has limited resources (such as wavelengths and time slots). In addition, QKD optical networks are also affected by external disturbances such as data interception and eavesdropping, resulting in inefficient network communication. In this paper, we exploit the idea of protection path to enhance the anti-interference ability of QKD optical network. By introducing the concept of security metric, we propose a routing wavelength and time slot allocation algorithm (RWTA) based on protection path, which can lessen the blocking problem of QKD optical network. According to simulation analysis, the security-metric-based RWTA algorithm (SM-RWTA) proposed in this paper can substantially improve the success rate of security key (SK) update and significantly reduce the blocking rate of the network. It can also improve the utilization rate of resources such as wavelengths and time slots. Compared with the non-security-metric-based RWTA algorithm (NSM-RWTA), our algorithm is robust and can enhance the anti-interference ability and security of QKD optical networks.