Quantum key distribution (QKD)-enabled optical networks utilize quantum mechanics to secure communications by establishing secure quantum channels. A critical criterion for QKD-enabled optical networks is ensuring network availability, which requires each quantum key service to adhere to a maximum unavailability constraint to maintain the network availability. This paper addresses the challenge of offering dedicated path protection for quantum key services in QKD-enabled optical networks. It ensures that the unavailability gap between the working and protection paths remains within the allowable limit for each quantum key service, adhering to specific unavailability constraints. Considering the constraints of the limited timeslot resources and network availability, we proposed quantum key service approach named a maximum availability (MA) algorithm. Simulation results indicate that the MA algorithm surpasses both the traditional dedicated-path protection (TDP) and fixed dedicated-path routing (FDR) algorithms in reducing total timeslot consumption and enhancing average availability.

This paper addresses the virtual network (VN) mapping problems for the network profit optimization in space-division-multiplexing optical data center networks (SDM-ODCNs). We first define both link resource availability (LRA) and node resource availability (NRA) for the VN mapping optimization, by which an integer linear program (ILP) model and two VN mapping approaches are proposed to achieve the high network profit. Simulation results verify that our proposed LRA VN mapping approach achieves greatly close network performance to that by solving solutions of the integer linear program model and significantly outperforms its counterpart approaches. The improved network profits out of the VN mapping is as a result of well suppressed average crosstalk, rejection ratio of VNs, and spectrum fragmentation ratio in SDM-ODCNs.

Emerging machine learning techniques enable Internet-connected devices to generate service function chain (SFC) requests for reliability-sensitive applications. To facilitate reliable SFC provisioning, prior works have proposed the SFC dedicated protection approach for fog and cloud networks, which generally have abundant resources and connectivity. However, with limited resources and connectivity, it might be inefficient to directly employ these approaches at the network edge. In this work, we study how to efficiently embed and provide dedicated protection when accommodating SFCs at the network edge. We formally define the problem of SFC embedding with dedicated protection (SFCE-DP) to minimize the bandwidth resources usage at the network edge. Based on the proposed technique of augmenting path in a layered graph, we construct an efficient algorithm, called augmenting-path-based SFC embedding with dedicated protection (AP-SDP), to optimize SFCE-DP. When the network resources are limited, our results show that AP-SDP significantly outperforms the benchmark that is directly extended from the state-of-the-art.

This paper addresses the problems of core and spectrum assignment (CSA) in space-division-multiplexing (SDM) elastic optical networks (EONs) with multi-core fiber (MCF). We first present spectrum sensitivity (SS) of the crosstalk-sensitive core matrix to evaluate inter-core crosstalk (XT) in trench-assisted (TA) MCF. We then propose the XT-sensitive spectrum assignment to suppress XT. We consider both static and dynamic network planning based on the spectrum sensitivity. In the static scenario, an integer linear programming (ILP) model along with effective heuristic CSA algorithms are developed to suppress XT and improve the spectrum efficiency. In the dynamic scenario, two heuristic CSA algorithms are proposed aiming to initiate a graceful tradeoff between average crosstalk and spectrum efficiency. Simulation results demonstrate the superiority of the proposed CSA algorithms compared with the existing CSA algorithm in MCF-based SDM-EONs.

The spectrum efficiency is a greatly important issue when we establish connection requests in elastic optical data center networks (EODCNs). In this article, we address the spectrum efficiency problems of the shared-path protection with spectrum-sharing-maximized approaches for the optical network survivability. Two integer linear program (ILP) models, i.e., flow-based and path-based ILP models, named FB-ILP and PB-ILP, are developed to minimize the frequency slots (FSs) occupied with the spectrum-sharing-maximized protection, and two heuristic approaches with the spectrum-sharing-maximized protection (HA-SSMP) and with the general spectrum-sharing protection (HA-GSSP) are also proposed to improve spectrum efficiency in EODCNs. For comparison, we introduce a heuristic approach with the existing shared-path protection (HA-ESPP) in EODCNs. On the one hand, simulation results show that FB-ILP can minimize the number of FSs occupied, but leads to the higher average number of hops and longer running time compared to PB-ILP, HA-SSMP, HA-GSSP, and HA-ESPP in static traffic scenario in EODCNs. On the other hand, the simulation results of our proposed HA-SSMP are very close to the solutions of FB-ILP. In dynamic traffic scenario, simulation results show that HA-SSMP significantly improves the spectrum efficiency and effectively suppresses the blocking probability, but leads to the higher average number of hops compared to HA-GSSP and HA-ESPP in EODCNs.

In this article, the network performance of equilibrium allocation of quantum key resources was investigated in quantum key distribution (QKD)-enabled optical data center networks. To effectively use quantum key resources, we propose three novel efficient load balancing routing, wavelength, and time-slot assignment (LB-RWTA) approaches, including LB-RWTA with flexible security level (LB-RWTA-FSL), LB-RWTA with specific security level (LB-RWTA-SSL), and LB-RWTA without security level (LB-RWTA-NSL). Particularly, the proposed LB-RWTA-FSL approach is uniquely featured by adaptive security level classification (ASLC) and load balancing (LB), aiming to demarcate the security level (SL) and reduce the overall network congestion. We introduce an existing routing, wavelength, and time-slot assignment (E-RWTA) approach without SL, called E-RWTA, for comparison. Simulation results show the effectiveness of our proposed approaches in terms of much higher quantum key resource efficiency and thus much higher network security performance than the state-of-the-art quantum key resource allocation approaches compared with the E-RWTA approach in QKD-enabled optical data center networks.

Due to the accelerated evolution of application services, optical network virtualization simplifies optical-layer resource management and provides flexibility in spectrum resource allocation. However, the energy consumption is one of the great challenges in the virtual optical networks (VONs). This paper focuses on the energy efficiency problem in survivable VONs with the sliceable multi-flow transponders and the elastic regenerators. For each VON, all virtual links provide the dedicated-path protection in the flexible bandwidth optical networks. An integer linear program (ILP) and a minimum unit-energy submatrix (MinEnSub) VON mapping approach are developed to improve the energy efficiency, minimize the power consumption, and reduce the spectrum usage under different line rates. For comparison, a baseline VON mapping approach is introduced. Simulation results show that the ILP model and the proposed MinEnSub VON mapping approach can save power consumption, improve the energy efficiency, and reduce the spectrum usage compared with the baseline VON mapping approach in a 6-node network. As expected, in a 14-node network, simulation results also validate that our proposed MinEnSub VON mapping approach can achieve better performance in terms of power consumption, energy efficiency, number of frequencies, and the number of regenerators.

This paper addresses the minimum network cost problem for survivable virtual optical network mapping in flexible bandwidth optical networks. We develop an ILP model and the LBSD (the largest bandwidth requirement (LB) of virtual links versus the shortest distance (SD)) mapping approach to minimize the network cost for a given set of VONs, and we introduce two baseline mapping approaches, named LCLC (the largest computing resources' requirement versus the largest computing resources' provisioning (LC)) and LCSD (the largest computing resources' requirement versus shortest distance) mapping approaches, for comparison. Simulation results show that LBSD can achieve network cost near the ILP solutions in a 6-node network. Also, LBSD greatly reduces the cost, the spectrum usage, and the number of regenerators compared to LCLC and LCSD in the 6-node and NSFNET networks.

This paper addresses the problem of minimizing spectrum usage for shared-path protection with joint failure probability constraint in flexible bandwidth optical networks. To achieve this goal, we propose an integer linear programming (ILP) model for shared-path protection and a heuristic spectrum-aware shared protection (SASP) algorithm that considers joint failure probability. Simulation results show that the ILP model minimizes the total usage of frequency slots and average hops, but leads to high average joint failure probability. Moreover, the SASP algorithm achieves better trade-off between total usage of frequency slots and average joint failure probability compared to the ILP model and a conventional shared-path protection (CSPP) algorithm. As expected, in a 14-nodes network, the SASP algorithm performs better with respect to total spectrum usage and average hops, but results in much larger average joint failure probability compared to the CSPP algorithm.