The variant cycle-cover problem in fault detection and localization for mesh all-optical networks

With the soaring channel speed and density in all-optical networks (AONs), the risk of high data loss upon network faults increases quickly. To manage network faults efficiently, an m-cycle based fault detection and localization (MFDL) scheme has been introduced recently. This paper verifies the necessary and sufficient condition for achieving the complete fault localization (CFL) in MFDL, which is defined as the case that every single network fault can be located to a unique link. We model the m-cycle construction as a new mathematical problem: the variant version of the constrained cycle-cover problem (vCCCP) and explore its formal expression. The model includes the consideration of the cycle-length limit, cycle number, and wavelength cost, while also keeps the CFL achievable. A two-phase branch-and-bound (B&B) algorithm was developed for solving the vCCCP, which guarantees to find near-optimal solutions. This algorithm is then applied to four typical and four random network examples to validate and assess the performance. The results are analyzed and compared with some previously reported algorithms, in terms of fault localization degree, cycle number, wavelength overhead, and cost reduction. The performance evaluation and comparison reveal that the new model and algorithm could significantly reduce the MFDL cost, including both the cost of monitoring devices and reserved wavelengths.     

Cross-talk attack monitoring and localization in all-optical networks

The effects of an attack connection can propagate quickly to different parts of an all-optical transparent network. Such attacks affect the normal traffic and can either cause service degradation or outright service denial. Quick detection and localization of an attack source can avoid losing large amounts of data in an all-optical network. Attack monitors can collect the information from connections and nodes for diagnostic purpose. However, to detect attack sources, it is not necessary to put monitors at all nodes. Since those connections affected by the attack connection would provide valuable information for diagnosis, we show that by placing a relatively small number of monitors on a selected set of nodes in a network is sufficient to achieve the required level of performance. However, the actual monitor placement, routing, and attack diagnosis are challenging problems that need research attention. In this paper, we first develop our models of crosstalk attack and monitor node. With these models, we prove the necessary and sufficient condition for one-crosstalk-attack diagnosable networks. Next, we develop a scalable diagnosis method which can localize the attack connection efficiently with sparse monitor nodes in the network.     

Binary quadratic programming formulation for routing and wavelength assignment problem in all-optical WDM networks

Routing and wavelength assignment (RWA) is the most concern in wavelength routed optical networks. This paper proposes a novel binary quadratic programming (BQP) formulation for the static RWA problem in order to balance traffic load among a network links more fairly. Subsequently, a greedy heuristic algorithm namely variable-weight routing and wavelength assignment (VW-RWA) is proposed to solve the developed BQP problem. In this method, the weight of a link is proportional to the link congestion. Performance evaluation results for different practical network topologies show that our proposed algorithm can decrease the number of required wavelengths in the network, blocking rate and variance of used wavelengths in each link. Besides, it is shown that the number of required wavelengths to establish call requests for a given network topology can be reduced at lower cost compared to other heuristics.     

Fault and attack management in all-optical networks

Network management for optical networks faces additional security challenges that arise by using transparent optical network components in communication systems. While some available management mechanisms are applicable to different types of network architectures, many of these are not adequate for all-optical networks. These have unique features and requirements in terms of security and quality of service, thus requiring a much more targeted approach in terms of network management. In this article we consider management issues with particular emphasis on complications that arise due to the unique characteristics and peculiar behaviors of transparent network components. In particular, signal quality monitoring is still a major complication in all-optical networks. Despite new methods for detection and localization of attacks having been proposed, no robust standards or techniques exist to date for guaranteeing the quality of service in these networks. Therefore, sophisticated mechanisms that assist in managing and assessing the proper function of transparent network components are highly desirable. Accordingly, we present an algorithm for multiple attack localization and identification that can participate in some tasks for fault management of all-optical networks     

针对虫洞攻击的无线传感器网络安全定位方法

节点定位技术是无线传感器网络的关键技术之一,是很多基于无线传感器网络的应用的基础。然而,无线传感器网络通常部署在无人值守的敌对环境中,攻击节点能够很容易地破坏网络中节点的定位过程。本文针对无线传感器网络中距离无关的定位技术,分析了虫洞攻击对DV-Hop定位过程的影响,提出了一种无线传感器网络中抵御虫洞攻击的DV-Hop安全定位方法。仿真结果表明所提出的安全定位方法能够有效降低虫洞攻击对DV-Hop定位过程的影响,验证了该方法的有效性。     

An efficient dynamic distributed optical link establish method in intelligent all-optical networks

In this article, an efficient, fast, and dynamic distributed optical link setup method is proposed. Two kinds of novel optical fast link release mechanisms (Ahead and Timeout Release) are presented for an optical-link establishment. They can dramatically reduce the blocking probability. For dynamic routing detection, a new kind of dynamic weighted Dijkstra algorithm (DW-DA) along with dynamic optical link load balancing is described. A variable mutation and crossover rates of a genetic algorithm (VMCR-GA) is used for fast wavelength assignment with two-novel-wavelength assignment rules in a wavelength relationship graph, which can reduce the necessary wavelengths and link establishment time. Through simulation giving the blocking probability and the time for link establishment on several well-known networks, the effectiveness of this method has been verified. The blocking probability of the network can be reduced significantly below that of normal routing and wavelength assignment (RWA). Furthermore, the calculating time for reaching the minimum blocking probability can be reduced dramatically.

A new architectural approach for optical burst switching networks based on a common control channel

The new architectural approach to Optical Burst Switching networks presented here features a common control channel and a node locally maintained network model. The Common Control Channel allows for a fast and efficient broadcast of the network Control Packets, which in turn are used by every node to update its Local Network Model. The Local Network Model allows efficient network resource planning as each node is aware of the reservation status intentions for the resources on each node. This paper describes the new C³-OBS architecture, evaluates its comparative performance to regular OBS, assesses the manageable bandwidth for a C³-OBS network and evaluates the common control channel manageable load. The concept of “Well-Informed Node” is defined as a metric of trustfulness on the information managed by the Local Network Model and the scope and application of C³-OBS networks are studied.     

Game theory-based attack and defense analysis in virtual wireless networks with jammers and eavesdroppers

Dynamic spectrum sharing and cognitive radio networks were proposed to enhance the Radio Frequency (RF) spectrum utilization. However, there are several challenges to realize them in real systems, such as sensing uncertainty causing issues to licensed users, business models for licensed service providers. Wireless virtualization is regarded as a technology that leverages service level agreements to sublease unused or underutilized RF spectrum that addresses aforementioned issues and helps to significantly enhance the utilization of the RF spectrum, offer improved coverage and capacity of networks, enhance network security and reduce energy consumption. With wireless virtualization, wireless networks' physical substrate is shared and reconfigured dynamically between virtual wireless networks through Mobile Virtual Network Operations (MVNOs). Wireless virtualization with dynamic configurable features of Wireless Infrastructure Providers (WIPs), virtualized wireless networks are vulnerable to a multitude of attacks, including jamming attacks and eavesdropping attacks. This paper investigates a means of defense through the employment of coalition game theory when jammers try to degrade the signal quality of legitimate users, and eavesdroppers aim to reduce secrecy rates. Specifically, we consider a virtual wireless network where MVNO users' job is to improve their Signal to Interference plus Noise Ratio (SINR) while the jammers target to collectively enhance their Jammer Received Signal Strength (JRSS), and an eavesdropper's goal is to reduce the overall secrecy rate. Numerical results have demonstrated that the proposed game strategies are effective (in terms of data rate, secrecy rate and latency) against such attackers compared to the traditional approaches.     

无线传感器网络中检测女巫攻击的节点定位方法

为了有效抵制女巫攻击,在攻击存在的情况下提高无线传感器网络节点的定位精度,分析、总结了女巫攻击所固有的薄弱环节,提出了基于接收功率验证的检测女巫攻击的节点安全定位方法。检测机制分为两步,首先检测节点通过比较接收功率,从所接收的全部信标节点中选择出距其距离相同的信标节点,列为可疑Sybil节点,然后通过邻居节点间的信息交互和距离验证,最终检测出攻击节点,利用去除了Sybil节点的信标节点集合实现定位。仿真实验显示,当存在攻击时,检测成功概率能达到95%以上,定位精度提高了9～11.64 m,表明该方法能有效检测女巫攻击,实现节点安全定位。     

光网络中的光交换技术

在对光交换技术深入研究的基础上，对光网络中的关键器件，声光可调滤波器及光缓存器作了详细介绍，最后对光交换的发展前景作了展望。     

Ad_hoc网络动态密钥管理

阐述了当前ad　hoc网络中有关认证和密钥管理的研究概况,特别论述了SecurePebblenets方法中密钥管理节点的生成,对节点加入和退出处理进行更详细分析,并补充了节点变化对簇的影响,对于ad　hoc网络密钥管理的研究具有一定参考价值。     

A new approach for routing and wavelength assignment for permanent and reliable wavelength paths in wide all-optical WDM networks

This article proposes a new approach for routing and wavelength assignment (RWA) for permanent and reliable wavelength paths (WP) in wide all-optical WDM networks with wavelength continuity constraint. Given a number of available wavelengths on each optical fiber, for each simple link failure of the network, we seek to maximize the number of satisfied requests for connections. This is known as RWAP problem. In our algorithm, called RWA with Minimum Loaded Link for Permanent and Reliable wavelength paths (MLL-PR), routing is based on the search for the optimal path while trying to minimize the maximum load on the links of the network in order to minimize the maximum link capacity and then minimize the number of dropped lightpaths after any link failure. The wavelength assignment is based on a graph coloring method using tabu-search. A series of experiments using two well-known networks (ARPANET and NSFNET) have been carried out in order to evaluate the performance of our approach, in terms of the number of blocked demands, for different failure scenarios. Generally, our results are better than those provided by the current solving approaches taken as reference.

A Novel Fault Detection and Localization Scheme for Mesh All-optical Networks Based on Monitoring-cycles

We previously showed the feasibility of a fault detection scheme for all-optical networks (AONs) based on their decomposition into monitoring-cycles (m-cycles). In this paper, an m-cycle construction for fault detection is formulated as a cycle cover problem with certain constraints. A heuristic spanning-tree based cycle construction algorithm is proposed and applied to four typical networks: NSFNET, ARPA2, SmallNet, and Bellcore. Three metrics: grade of fault localization, wavelength overhead, and the number of cycles in a cover are introduced to evaluate the performance of the algorithm. The results show that it achieves nearly optimal performance.     

Non-data-aided joint bit-rate and modulation format identification for next-generation heterogeneous optical networks

A novel and cost-effective technique for simultaneous bit-rate and modulation format identification (BR-MFI) in next-generation heterogeneous optical networks is proposed. This technique utilizes an artificial neural network (ANN) in conjunction with asynchronous delay-tap plots (ADTPs) to enable low-cost joint BR-MFI at the receivers as well as at the intermediate network nodes without requiring any prior information from the transmitters. The results of numerical simulations demonstrate successful identification of several commonly-used bit-rates and modulation formats with estimation accuracies in excess of 99.7%. The effectiveness of proposed technique under different channel conditions i.e. optical signal-to-noise ratio (OSNR) in the range of 14–28 dB, chromatic dispersion (CD) in the range of −500 to 500 ps/nm and differential group delay (DGD) in the range of 0–10 ps, is investigated and it has been shown that the proposed technique is robust against all these impairments.     

Target localization based on energy considerations in distributed sensor networks

Wireless distributed sensor networks are important for a number of strategic applications such as coordinated target detection, surveillance, and localization. Energy is a critical resource in wireless sensor networks and system lifetime needs to be prolonged through the use of energy-conscious sensing strategies during system operation. We propose an energy-aware target detection and localization strategy for cluster-based wireless sensor networks. The proposed method is based on an a posteriori algorithm with a two-step communication protocol between the cluster head and the sensors within the cluster. Based on a limited amount of data received from the sensor nodes, the cluster head executes a localization procedure to determine the subset of sensors that must be queried for detailed target information. This approach reduces both energy consumption and communication bandwidth requirements, and prolongs the lifetime of the wireless sensor network. Simulation results show that a large amount of energy is saved during target localization using this strategy.     

光纤光栅在全光通信网中的应用

随着社会对通信业务需求的不断增加,基于DWDM的全光网络已成为未来光通信的发展趋势,光纤光栅具有附加损耗小,体积小,能与光纤很好地耦合,可与其他光纤器件融成一体等特性,这将使光纤光栅成为未来全光网中的基石,从目前的研究来看,光纤光栅已经能够为全光通信系统不光源,光放大,色散补偿,OTM（光终端复接器）,OTDM（光时分复用）,OXC（光交叉连接）等等关键部件提供优秀的解决方案。     

Wireless image sensor networks: event acquisition in attack-prone and uncertain environments

Wireless Image Sensor Networks (WISNs) consisting of untethered camera nodes and sensors may be deployed in a variety of unattended and possibly hostile environments to obtain surveillance data. In such settings, the WISN nodes must perform reliable event acquisition to limit the energy, computation and delay drains associated with forwarding large volumes of image data wirelessly to a sink node. In this work we investigate the event acquisition properties of WISNs that employ various techniques at the camera nodes to distinguish between event and non-event frames in uncertain environments that may include attacks. These techniques include lightweight image processing, decisions from n sensors with/without cluster head fault and attack detection, and a combination approach relying on both lightweight image processing and sensor decisions. We analyze the relative merits and limitations of each approach in terms of the resulting probability of event detection and false alarm in the face of occasional errors, attacks and stealthy attacks.

Self-configurable fault monitoring in ad-hoc networks

While fault monitoring is a well-known issue in fixed wired networks, ad-hoc networks provide new challenges with respect to this issue: in particular, the monitoring task may be hindered at any time by the impossibility to observe a given node. This paper proposes a fault monitoring approach for ad-hoc networks which takes into account this constraint. Our approach is based on an information theory measure suitable to the intermittence of ad-hoc nodes and capable to detect network failures by inference. We define a distributed monitoring scheme with several collaborative detection methods, and we detail a self-configuration mechanism based on the K-means classification algorithm. We show how this solution can be integrated into a management architecture and evaluate its performance based an extensive set of simulations.     

Cryptanalysis of some user identification schemes for distributed computer networks

User identification plays an important role for access control in networks. Recently, Hsu and Chuang proposed a user identification scheme for distributed computer networks, which can also provide key agreement and user anonymity. However, Tsai pointed out the weakness of Hsu–Chuang's scheme and proposed an improved scheme. In this paper, we present two attacks to examine that some user identification schemes have a serious security loophole. Finally, we propose a new user identification scheme, which is more secure than the existing schemes.Copyright © 2013 John Wiley & Sons, Ltd.     

WDM全光网自适应路由和波长分配算法

研究了无波长转换WDM全光网的路由和波长分配算法（RWA）。通过对已有算法的分析和比较,提出了一种自适应最小跳数路由算法（ADMH）。此算法以最小跳数路由为基础,同时考虑网络状态的变化,因而不仅能尽量少使用网络资源,也能使网络资源的分布保持均衡。计算机模拟仿真的结果表明,这种算法性能在各种网络参数条件下优于或等于已有算法。