基于MHBT的数据库隔离与恢复模型

新时期随着信息化技术的高速发展,网络普及率惊人的速度增长,网络应用软件的访问时间几乎遍布于全天的各个时间,随之带来的是对基础支持类软件——数据库可生存性的新属性要求,即要能够持续不间断的提供服务,即使是在受到某些恶意攻击时.传统的数据库恢复技术在执行恢复任务时都需要数据库停止工作,并且恢复操作是基于检查点,即恢复检查点之后的所有事务操作,盲目性强,耗费时间较多.本文通过对当前数据库可生存性研究中隔离与恢复研究的分析总结,提出了基于MHBT树结构的数据库隔离与恢复技术,并通过对模型的数学分析评估了其运行效率.     

可生存性分析方法研究

系统在受到入侵后依然能够提供必要服务,并在一定时间内恢复受侵害的服务是系统可生存性的本质要求,与传统的将可生存性作为非功能系统属性描述的方法不同,将可生存性作为系统统一系统功能来研究,并用形式化语言来描述,定义和计算是一种全的思路和方法,对可生存性分析阶段可以采用的方法进行了深入的研究,分析,其中重点阐述了工作流回溯,攻击树建立等可生存性需求分析的方法,并给出了可生存性量化分析的算法。     

业务量疏导WDM网状网中的动态子通路保护算法

该文研究了业务量疏导WDM网状网中的生存性问题,提出一种自适应子通路保护(ASPP)算法。该算法根据网络当前状态以及到达业务连接请求的带宽要求动态调整链路权值;在此基础上选择一条最短路作为工作通路,然后将该通路分为互不重叠的n段子通路(每段经过的链路数为m),并分别找出各自的保护通路。仿真结果表明：ASPP既可以保证业务连接的可靠性要求,同时又允许网络管理者根据一定优化策略调整m值,从而可以在资源利用率和恢复时间之间进行折中。     

应对灾难风险的多虚拟机快速协同撤离机制研究

大规模灾难事件可能对通信网基础设施造成严重的威胁和破坏。针对大规模灾难风险下虚拟网的生存性问题,该文提出一种多虚拟机快速协同撤离(MRCE)机制。该机制采用后复制迁移技术实现虚拟机的在线迁移,通过基础迁移带宽的分配和升级,对属于同一虚拟网的多个风险虚拟机进行快速协同撤离,以减少单个虚拟网的撤离完成时长,降低损毁风险。仿真结果表明,该机制能在不同考察周期内获得较好的虚拟网撤离完成率和平均撤离完成时长。     

Optimal multilevel protection in series–parallel systems

This paper considers vulnerable systems that can have different states corresponding to different combinations of available elements composing the system. Each state can be characterized by a performance rate, which is the quantitative measure of a system's ability to perform its task. Both the impact of external factors (attack) and internal causes (failures) affect system survivability, which is determined as the probability of meeting a given demand.In order to increase the system's survivability a multilevel protection is applied to its subsystems. This means that a subsystem and its inner level of protection are in their turn protected by the protection of an outer level. This double-protected subsystem has its outer protection and so forth. In such systems, the protected subsystems can be destroyed only if all of the levels of their protection are destroyed. Each level of protection can be destroyed only if all of the outer levels of protection are destroyed.In such systems, different protections play different roles in providing for the system's survivability. Subject to budget limitations a question arises which protections should be applied to obtain the desired survivability. An algorithm for solving the protection cost minimization problem subject to survivability constraint is presented in the paper. The algorithm is based on a universal generating function technique used for system survivability evaluation and on a genetic algorithm used as an optimization engine.Illustrative example is presented.     

多弹头对陆基战略导弹突防效果和有效性的影响

经分析认为,分导式多弹头的效能在弱国是无法发挥的,受各种因素的制约,多弹头导弹的突防能力、生存能力和总的有效性都远不及相同弹头数量的单头导弹的齐射.     

Selective survivability with disjoint nodes and disjoint lightpaths for layer 1 VPN

This paper deals with the problem of survivable routing and wavelength assignment in layer 1 virtual private networks (VPNs). The main idea is routing the selected lightpaths by the layer 1 VPN customer, in a link-disjoint manner. The customer may freely identify some sites or some connections, and have their related lightpaths routed through link-disjoint paths through the provider’s network. This selective survivability idea creates a new perspective for survivable routing, by giving the customer the flexibility of selecting important elements (nodes or connections) in its network. This study is different from previous studies which aim to solve the survivable routing problem for the whole VPN topology. The proposed scheme is two-fold: disjoint node based, and disjoint lightpath based. In disjoint node scheme, all lightpaths incident to a node are routed mutually through link-disjoint paths. In disjoint lightpath scheme, a lightpath is routed in a link-disjoint manner from all other ligthpaths of the VPN. We present a simple heuristic algorithm for selective survivability routing. We study the performance of this algorithm in terms of resources allocated by the selective survivability routing scheme compared to shortest path routing with no survivability. The numerical examples show that the amount of used resources by the selective survivability scheme is only slightly more than the amount used in shortest path routing, and this increase is linear. The extra resources used by the new scheme are justified by better survivability of the VPN topology in case of physical link failures, and the simplicity of the implementation.     

Optical network design to minimize switching and transceiver equipment costs

We consider a network consisting of N nodes and a certain number of links M that could be used to interconnect these nodes. The problem we address is to determine the smallest subset of switching nodes (in which to provide optical or electronic switching capability) necessary and sufficient to provide full end-to-end connectivity among all nodes. It is shown that this selection leads to the minimum number of transceivers needed to achieve full connectivity. We then address the same problem with the additional requirement of survivability, whereby the failure of any one link does not lead to any disconnection in the network. To solve the above stated problems, we employ heuristic and optimal algorithms; we find that the minimum number of switching sites is well estimated as a function of a single parameter, the network connectivity . (This is an extended version of the paper presented at Broadnets 2006.)     

可信计算及其关键技术研究

The dependability is the latest and highest techno-target used to evaluate the performance quality of a dis-tributed computing system in open network environment, it includes traditional reliability, availability, robustness,survivability, security, data integrity and software protecting ability, etc. A dependable system should not only be provided with fault tolerance ability, but also withstand from risk and recover from disaster, its realization foun dationis the high availability of the information transmission Jaetwork and survivability, fault tolerance and security safe-guard of the system. This paper presents a survey of the survivability mechanisms such as long-distance backup, clus-ter and system recovery, while discussing the techniques of fault tolerance design and information network system se-curity safeguard, and analyzing the information redundant dispersal strategy and model for survivability and security safeguard.     

具有多重故障恢复能力的光网络生存性机制

为了解决多重故障情况下网络发生故障后能尽快地恢复 受影响的业务这一问题，提出了一种具有多重故障恢复能力的光网络生存性机制. 针对传 统子网路由法存在的问题，给出了相应的改进方案：在子网路由法中考虑了对共享分享链路 组的恢复问题；在子网路由法中引入了选路原则. 在采用子网路由法的基础上探讨了二次故 障的生存性方法，并从有效利用率的角度对所给出的改进方案进行了仿真和分析.