Design of Reliable IP/GMPLS Networks: An Integrated Approach

The increased bandwidth demand for new Internet applications suggests mapping IP directly over the wavelength-division multiplexing (WDM) layer. Since reliability is such a critical issue in these broadband networks, we propose an integrated design method which addresses the problem of survivability as viewed from the IP/MPLS layers but taking into account the failure mechanisms in the optical layer. This approach is becoming practical because of the emergence of generalized multiprotocol label switching (GMPLS) as a multilayer control plane that can support the signaling required for coordinating the restoration mechanisms in multiple layers.The model relies on network calculus to evaluate a quality of service (QoS) metric as actually perceived by end users and computes a preplanned restoration scheme to recover from failures. We discuss the numerical implementation, the convergence and the solutions produced by the algorithm and show that the resulting network can provide the prescribed QoS guarantees for all failure states.     

基于随机Petri网的电信交换系统可生存性分析

网络系统的可生存性问题是系统安全领域的一个重点研究方向。讨论现有的系统可生存性的一般分析方法,确定系统的可生存属性,并采用随机Petri网(SPN)技术,分析电信交换系统生存性问题的特点。重点利用随机Petri网描述系统的失效-修复分析模型和性能分析模型,给出系统可生存性分析中主要指标的定量计算方法。系统仿真结果表明了该方法的有效、合理性。     

网络生存性研究概述

网络系统逐步成为现在社会系统的关键组成部分,许多方面的关键应用越来越依赖于网络系统的运转,如交通控制和国防信息系统等。然而这种网络依赖性带来的风险和网络系统所面临入侵、事故、失效等的威胁将不仅影响网络系统的本身,而且已扩大到其它的系统领域。主要给出了网络生存性定义及研究内容,并讨论了提高网络系统生存性的解决方法。     

基于Hash函数和自动恢复技术的网站抗毁系统研究与实现

文章提出了一种基于Hash函数和自动恢复技术的网站抗毁系统模型,介绍了一个基于该模型的“磐石”网站监控与自动恢复系统的组成结构和实现机制。讨论了该系统实现中的一些关键技术,并介绍了该系统的主要功能和特点及典型应用环境。最后给出了该项目今后的工作方向。     

Availability guarantee in survivable WDM mesh networks: A time perspective

Since availability is an important quality-of-service (QoS) factor in mesh networks, different service provision with availability guarantee have been discussed by many researchers in the literature. However, with the increasing demand for mesh networks to support both data and real-time multimedia traffic, multiple availability requirements may be made during one connection’s holding time. The traffic of different availability requirements has to be routed by special wavelengths. In this paper we discuss availability guarantee in mesh networks from the perspective of time and propose a new scheme called Time Aware Availability Guarantee (TAAG). The routing paths of each connection are adjusted according to the different availability requirements in different time spans. Simulation results show that the proposed scheme outperforms the previous schemes such as Time Unaware Availability Guarantee (TUAG) in terms of resource utilization, blocking probability and traffic throughput.     

Intelligence and impact contests in systems with redundancy, false targets, and partial protection

The paper considers a system consisting of identical elements that can be intentionally attacked. The cumulative performance of the system elements should meet a demand. To prevent loss of demand the defender provides system redundancy (deploying genuine system elements (GEs) with cumulative performance exceeding the demand); deploys false elements (FEs), and protects the GEs. If the attacker cannot distinguish GEs and FEs, he chooses the number of elements to attack and attacks at random these elements distributing his resource evenly among the attacked elements. In order to get the information about the system the attacker allocates a part of his resource into the intelligence activity. Analogously, the defender allocates a part of his resource into the counter-intelligence activity. The attacker's strategy presumes distribution of his resource among the intelligence and attack effort and choice of the number of attacked elements. If the attacker wins the intelligence contest, he can identify both FEs and unprotected GEs ignoring the former ones and destroying the latter ones with negligible effort. The defender's strategy presumes distribution of his resource among the counter-intelligence and the three defensive actions. The paper considers a three-period non-cooperative minmax game between the defender and the attacker and presents an algorithm for determining the agents’ optimal strategies.     

机动状态下雷达装备抗毁性评估研究

本文基于层次分析法建立了机动状态下雷达装备生存能力综合评估模型,研究了运用专家经验评判的权重确定标准和雷达战、技性能指标的评估指数量化模式,对机动状态下的雷达装备的抗毁性进行了定量的综合指数评定方法。最后对某型雷达的系列装备的机动抗毁性进行了评估分析,验证了该方法的正确性。     

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.