生存光传输网络的交叉连接模块结构

基于波分复用技术的光传输网络在克服当前网络容量瓶颈的同时又面临网络生存的挑战,它必须快速、有效地恢复因网络故障而受损的工作光路。该文分析了四种基本网络恢复技术以及与之相对应的OXC节点模块结构,即:保留光纤链路方式、保留波长链路方式、保留波长路径方式以及动态波长路径方式;并从光连接恢复时间、网络资源效率和控制复杂度三个侧面比较了不同OXC结构对于网络生存的影响。     

Protection based on backup radios and backup fibers for survivable Fiber-Wireless (FiWi) access network

In Fiber-Wireless (FiWi) access network, the optical back-end is vulnerable to the network component failure due to its tree topology. Any failure at the optical back-end may cause huge data loss. Thus, the survivability in FiWi is an important issue, especially the protection for the optical back-end. Some works propose to protect the optical back-end in FiWi by means of the wireless rerouting in the wireless front-end. However, these works cannot guarantee that there are always the available wireless paths for the traffic rerouting. In this paper, we divide the failures at the optical back-end into ONU-level failure and OLT-level failure according to the failure severity. To tolerate the ONU-level failure, we allocate each ONU a partner ONU and establish the wireless-backup-path between them by deploying backup radios on the traversed wireless routers. To tolerate the OLT-level failure, we cluster all segments in the network and place the backup fibers among the segments in each cluster to establish the protection ring. Thus, each pair of segments in the same cluster can backup for each other along the optical-backup-paths on the protection ring. We propose the heuristic algorithms to minimize the cost of backup radios and the cost of backup fibers. The simulation results demonstrate that the proposed algorithms are effective in enhancing the survivability of FiWi, while requiring less cost than the previous works.     

超立方体多处理机系统中基于扩展最优通路矩阵的容错路由

该文在高峰等文章的基础上，提出了针对超立方体结构多处理机系统的扩展最优通路矩阵（Extended Optimal Path Matrices,EOPMs）的概念，并给出了一个建立EIPMs的算法和基于EOPMs的容错路由算法，证明了基于EOPMs的容错路由算法是基于扩展安全向量（ESVs）^[13]和基于最优通路矩阵（OPMs)^[14]容错路由算法的扩展，与原文相比，该算法的存储开销与OPMs,相同，但记录的最优通路的信息，包含了原文所记录的最优通路的信息，使搜索最优通路的能力比它们有进一步的提高。     

On the Construction of Fault-Tolerant Cube-Connected Cycles Networks

This paper presents a new approach to tolerating edge faults and node faults in (CCC) networks of Cube-Connected Cycles in a worst-case scenario. Our constructions of fault-tolerant CCC networks are obtained by adding extra edges to the CCC. The main objective is to reduce the cost of the fault-tolerant network by minimizing the degree of the network. Specifically, we have two main results. (i) We have created a fault tolerant CCC that can tolerate any single fault, either a node fault or an edge fault. When the dimension of the CCC is odd, the degree of the fault tolerant graph is 4. In the even case, there is a single node per cycle that is of degree 5 and the rest are of degree 4. (ii) We have created a fault-tolerant CCC, where every node has degree y + 2, which can tolerate any 2y − 1 cube-edge faults. Our constructions are extremely efficient for the case of edge faults-they result in healthy CCC networks that utilize all of the processors.     

Building Edge-Failure Resilient Networks

We consider the design of resilient networks that are fault tolerant against link failures. Resilience against link failures can be built into the network by providing backup paths, which are used in the eventuality of an edge failure occurring on a primary path in the network. We consider several network design problems in this context; these problems are motivated by the requirements of current high-speed optical networks. In all the following problems the objective is to provide resilience in networks while minimizing the cost incurred. The main problem under consideration in this paper is that of backup allocation: this problem takes as its input an already provisioned primary network and a parameter k, and allocates backup capacity on the edges of the underlying network so that all the demand can be routed even in the presence of k edge failures. We also consider a variant of this problem where the primary network has a tree topology, and it is required that the restored network retains a tree topology. We then address the problem of simultaneous primary and backup allocation: we are given specifications of the traffic to be handled, and the goal is to provision both the primary as well as the backup network. Finally, we investigate a single-commodity problem motivated by a pragmatic scenario in which the primary network is not known in advance and demands between source--sink pairs arrive online.     

Hop-Constrained Node Survivable Network Design: An Application to MPLS over WDM

In this paper, we address a hop-constrained node survivable network design problem that is defined in the context of multi-protocol label switching (MPLS) over wavelength division multiplexing (WDM) networks. At the lower WDM layer, we consider a maximum length constraint for optical connections between MPLS routers. At the upper MPLS layer, we consider survivability as well as maximum delay constraints. Survivability is guaranteed by routing each demand through D node-disjoint paths and maximum delay is guaranteed by constraining all paths to a maximum number of hops. An Integer Linear Programming model, based on the previous works by Gouveia et al. (Proc of IEEE INFOCOM, 2003, and Telecommunications network planning: innovations in pricing, network design and management, pp 167–180, 2006) is used to model the network design problem considering two different survivability mechanisms: path diversity (where each demand is equally split over the D paths) and path protection (where any D–1 out of the D paths have enough capacity to support the total demand). For both mechanisms, we use the NSFNet and EON real world networks to make a cost analysis of the design solutions for different values of D. In the path diversity mechanism, the results consistently show that greater values of D impose a cost penalty that is greater than the gain in the percentage of demand that is protected. In the path protection mechanism, where all traffic is totally protected, the results show that the network solutions obtained with D=3 node-disjoint paths have consistently lower costs than the network solutions obtained with D=2 node-disjoint paths. However, using values of D that are greater than 3 led to network solutions with larger costs. Supported by FCT project POCTI - ISFL - 1- 152.     

具有生存性的Overlay网络构建方法

针对现有网络在可靠性和服务质量方面所存在的缺陷,以增强网络生存性为目标,对现有IP网络的生存性机制进行了研究。以路径相异性为基础,提出一种具有生存性的Overlay网络构建方法。构建过程使用重叠惩罚思想为每个源—目的对按照业务的QoS参数计算合适的路径,由这些路径构成节点对之间的Overlay虚拟拓扑。此网络拓扑不仅可以保证故障情况下的合理路径快速倒换,而且可以满足业务的需求。使用路径相似度和路径查询时间两个指标对基于重叠惩罚的路径选择算法进行了评价,仿真结果表明本算法可以按照业务的参数计算出满足业务需求的合理路径,可以顺利地构造出面向业务的具有生存性的Overlay网络。     

网络信息系统的可生存性研究

可生存性技术是信息安全领域前沿的研究课题,有着广阔的应用空间,其研究结果可广泛用于安全关键的网络化应用系统及网络基础设施的入侵容忍安全防护中.然而,从其目前国内外研究现状来看,还远未达到实用化的程度.可生存性研究还是一个较有发展潜质的研究领域,首先对可生存性理论进行了系统化的研究与分析,通过分析目前常见网络服务模型的安...     

IP网络生存性研究综述

随着交互式应用和各种实时业务的增长对网络生存性要求的提高,IP网络的生存性研究受到了越来越多的关注。本文首先对IP网络生存性面临的问题以及影响因素作了概括,并且对目前有关纯IP网络生存性、MPLS网络生存性、IP网络与底层的生存性协调研究作了归纳总结,尤其对纯IP网络的生存性研究现状从多方面进行了比较详细的介绍,最后指出IP网络的快速重路由机制具有很好的实际应用潜力,保护恢复能力和服务质量在MPLS网络中的结合、动态多层保护则是未来IP骨干网生存性维护的发展方向。     

一种可自维护的无线传感器网络拓扑控制算法

在温室、救灾等环境监测过程中,无线传感器网络会因频繁发生自然故障和遭受恶意攻击而引起网络可生存性问题,针对这一问题提出了一种可自维护的具有抗毁性的拓扑控制算法。仿真结果表明,该算法能够简单有效地构建并维护容错拓扑结构,在节点失效时保证网络拓扑容错抗毁,使得无线传感器网络具有可生存的能力。     

Achieving maximum reliability in fault tolerant network design for variable networks

The objective of this paper is to present a novel method to achieve maximum reliability for fault tolerant optimal network design when network has variable size. Reliability calculation is most important and critical component when fault tolerant optimal network design is required. A network must be supplied with certain parameters that guarantee proper functionality and maintainability under worse situations. Many alternative methods for measuring reliability have been stated in literature for optimal network design. Most of these methods mentioned in literature for evaluating reliability may be analytical and simulation based. These methods provide significant way to compute reliability when network has limited size. Also, significant computational effort is required for growing variable sized networks. Therefore, a novel neural network method is presented to achieve significant high reliability for fault tolerant optimal network design in highly growing variable networks. This paper computes reliability with improved learning rate gradient descent based neural network method. The result shows that improved optimal network design with maximum reliability is achievable by novel neural network at manageable computational cost.     

Efficient path protection in bi-directional WDM systems

Bi-directional WDM transmission is a technique that allows data to be transmitted simultaneously in both directions of a fiber, with different sets of wavelength channels for each direction. Compared with unidirectional WDM systems, it not only saves the cost of deploying extra fibers, but also allows more flexible bandwidth provisioning. To exploit this flexibility, we investigate path protection schemes for bi-directional WDM transmission systems in this paper. With path protection, a call is accepted if and only if an active data path together with a disjointed backup path can be found in the network. With bi-directional WDM, backup resource sharing in both directions of a fiber is possible. Based on a set of judiciously designed link cost functions, two original path protection schemes are proposed in this paper, BiPro and BiProLP. BiProLP aims at further economizing the hardware cost incurred by BiPro. In contrast to the traditional unidirectional schemes, we show that both BiPro and BiProLP can yield noticeably lower call blocking probability, higher system capacity and shorter active/backup path length.     

PTN网络的二次断纤链路规划算法

在PTN（PacketTransportNetwork）网络规划建设中,需要对光纤链路留出备份带宽,以保证部分光纤断开时,受影响业务有足够的容量进行路由重组。这也是提高网络生存性的有效方法之一。文中首先遍历网络双链路的失效状态,然后断开网络中任意两条链路,通过逐次增加链路容量来保证失效业务能够重组路由;最后提出二次断纤链路容量规划算法并进行试验仿真。结果表明,该算法在节约网络带宽、降低建造成本以及故障容错方面有着良好性能,能够很好应用于传送网络的链路规划中。     

网络容错路由算法概率分析的一种新的方法

该文提出了一种新的概率分析方法来研究在给定结点错误概率的情况下超立方体网络强容错路由算法的容错性的概率。针对文中提出的基于新的局部连通性网络容错模型的高效的强容错路由算法犤1犦,该文首次严格证明了一个具有1024个结点的10维超立方体网络能够容许多达4.7%的错误结点而具有99%的概率确保找到正确结点组成的路径,而如果结点的错误概率不超过0.1%,则所有实际规模的超立方体网络能够具有99.9%的概率确保找到正确结点组成的路径。该算法的时间性能是最优的,且该算法构造的路径的长度不超过源结点和目的结点之间海明距离的两倍加上一个很小的常数。     

Priority-aware optical shared protection: An offline evaluation study

The availability of an optical connection is considered to be a critical service differentiator in WDM optical networks. In this regard, the design of a protection scheme that improves the availability of high priority optical connections and makes efficient use of optical resources is a major challenge faced by optical network operators. In a previous study, we proposed the so-called priority-aware shared protection survivability scheme as a potential solution to this design issue.In this paper, we complement our previous study. More specifically, we develop an offline study whose main purpose is to assess the efficiency of the priority-aware shared protection scheme. Through this study, we show that the priority-aware shared protection strategy as opposed to existing protection strategies is able to achieve the best tradeoff between optical resource usage and optical connections’ availability satisfaction.     

Reconfiguration for service and self-healing in ATM networks based on virtual paths

This paper presents a reconfiguration scheme resulting in capacity efficiency and fast restoration by utilizing the inherent benefits of Virtual Paths in ATM networks. The unified optimization of bandwidth reconfiguration is addressed so that switched ATM networks can support both service and survivability from a common pool of network spare capacity at a given time. The spare capacity is composed of idle bandwidth and freed up bandwidth from the switch pairs which have a surplus bandwidth. Fast restoration can be achieved by using the pre-optimized network spare bandwidth and preplanned backup Virtual Paths based on the link and node disjoint path routing scheme. The overall operation of the proposed self-healing strategy can be consolidated into distributed fault management functions at ATM layer based on Virtual Paths. The scheme enables a logical Virtual Paths ring protection switching in ATM networks.     

An optimal inherently stabilizing routing algorithm for star P2P overlay networks

Star graphs possess many desirable properties such as scalable node degrees and diameters, which are essential to facilitate reduced routing table sizes and low maximum path length for routing in large P2P networks. In addition, because a large number of disjoint paths are available and each data/replica in an n‐star can be placed in an (n − 1)‐star, load balancing and alleviation of network bottlenecks can be implemented in star P2P overlay networks. Therefore, star networks have been proposed as viable alternatives to existing overlay topologies for large P2P networks. In this paper, we propose an optimal stabilizing and inherently stabilizing algorithm for routing messages over all disjoint paths between two peers in a star P2P overlay network. The algorithm is optimal in terms of its time complexity in rounds and the length of the longest path traversed by the messages, and fault tolerant due to being stabilizing and inherently stabilizing, allowing the system to withstand transient faults. The algorithm can be used to increase network reliability and survivability in P2P networks. In addition, the usage of all disjoint paths to route messages between two peers leads to increased network bandwidth while distributing the communication overhead across the network and eliminating network bottlenecks in P2P networks. Copyright © 2016 John Wiley & Sons, Ltd.     

基于粒子群权值优化的网络可生存性增强方法

针对网络中发生频率最高的单链路瞬时故障,提出了一种应用粒子群算法优化链路权值来增强网络可生存性的方法。引入费用函数对利用率过高的链路赋以惩罚性的高费用来避免链路过载,以网络在无故障场景下最高链路费用与单链路故障场景下最高链路费用的加权和作为目标函数,建立了优化算法模型,并应用粒子群优化算法求解最优权值。实验结果表明,算法求得的权值可以使网络在故障条件下保持较低的链路利用率,避免了因流量转移而造成网络拥塞,增强了网络可生存性。     

Priority-enabled optical shared protection: An online efficiency evaluation study

The availability of an optical connection is considered to be a critical service differentiator in WDM optical networks. In this regard, the design of a protection scheme that is able to improve the availability of high priority connections while making efficient use of optical resources is a major concern for optical network operators. In a previous work, we proposed the so-called priority-aware shared protection as a potential survivability scheme for next generation WDM networks to deal with the previously exhibited concern.

This paper develops an online study whose main purpose is to assess the efficiency of the aforementioned protection scheme. Through this study, we show that the priority-aware shared protection strategy is able to achieve both the best efficiency in terms of resource usage and in terms of availability satisfaction rate compared to existing protection solutions.     

全光双向网络中的波长转换

在许多光学路由中,对于给定一组通讯路的集合,必须对有公共边的路安排相同的波长.为了充分利用光学的带宽,目的是安排尽量少的波长数.但有时候也考虑使用波长转换器. 如果一个顶点安装转换器,任何经过这个顶点的路都可以改变其波长.因此在某些顶点安装波长转换器后可以将波长的数目减少到一个拥塞界,因此,Wilfong和Winkler定义了一个顶点集 S,在S上安装转换器后,任何路集都可以分配数目等于拥塞界的波长,这样的集合S被称为充分集.研究在双向网络中的最小充分集问题,并把他转化为最小顶点覆盖问题.对此问题给出几个算法.