MPLS快速重路由多故障恢复算法的研究

传统的MPLS快速重路由技术在面对网络多故障的情况时有许多不足之处,为了更好的解决问题,提出一种新的MPLS快速重路由多故障恢复算法.算法采用Detour路径保护方式,对有不同备份路径经过的链路上的预留带宽资源进行共享管理,并为工作路径建立主、从备份路径.仿真实验结果显示,该算法能够有效减少备份路径上预留带宽资源消耗,对出现多故障的网络进行快速恢复.     

基于免疫原理的多拓扑路由生成算法

针对现有多拓扑路由生成算法存在存储资源利用不合理、多故障恢复能力无法有效适应网络环境等问题,提出了一种结合生物免疫原理的多拓扑路由生成算法。该算法以适应网络环境中常见的多故障为目标,根据免疫原理中抗原与抗体决定基无须完全吻合而只需关键部位相匹配的机制,将子拓扑生成看作免疫原理中的抗体产生,增强了多故障情况下的网络抗毁性,同时引入人工免疫算法来解决算法中的寻优问题。实验结果表明,该方法提高了网络在多故障环境下的抗毁性。     

基于MPLS的分级故障恢复机制

网络可靠性已经成为IP网的一个重要问题.目前关于IP网可靠性的讨论集中于MPLS的故障恢复机制.IETF提出了两种MPLS故障恢复模型保护交换和重路由,每种模型的恢复时间和资源开销是不同的.该文提出一种基于MPLS的分级故障恢复机制MBCR,它可以保证应用对可靠性和QoS的要求,同时使网络资源得到充分利用.     

基于混沌搜索的数字电路多故障测试生成

针对数字电路中多故障测试生成较难的问题,本文提出了基于混沌搜索的数字电路多故障测试生成算法。该算法先把多故障转换成为单故障,再用神经网络的方法对单故障电路构造故障的约束网络,最后用混沌搜索方法求解故障约束网络能量函数的最小值点获得原电路中多故障的测试矢量。在一些国际标准电路上的实验结果表明了本算法的可行性。     

可重构网络中基于相似度的自适应路由算法研究

传统IP网络中采用了基于IP地址的路由协议,而各种实时应用程序的出现,对网络性能提出了更高的要求。为了使各个节点在网络拓扑结构发生变化时仍能正确传输消息,提出了一种在可重构网络中使用的路由算法。该算法以内容中心网络中的发布／预订系统为原型,通过在代理节点之间发送查询请求和匹配响应消息,基于代理节点的相似度来确定消息传输的下一跳节点,同时避免了网络产生环路。实验表明该算法可以减少传输延时和跳数,具有动态性、实时性的特点。     

IP QoS路由算法研究综述

传统上所采用的“尽力而为”转发机制,已经不能满足用户的要求。IP网络如何提供QoS(服务质量)支持这一问题现已成为业界关注的焦点。近几年的研究表明网络路由算法对实现QoS起到了非常关键的作用,同时网络路由算法也是平衡网络负载和充分利用网络资源的重要保证。该文对当前研究的主要路由算法进行了详细的分析与归纳,并对其发展前景进行了展望。     

基于MPLS的IP语音网络恢复性能仿真分析*

提出了一种基于MPLS 的IP语音网络恢复性能评估方案,该方案利用OPNET Modeler工具构建一个基于MPLS的IP语音网络仿真平台,分析与评估基于MPLS的两种故障恢复技术。仿真结果表明,采用基于MPLS OAM技术的快速重路由算法可以有效地缩短流量重路由时间与改进IP语音网络服务质量,验证了基于MPLS OAM技术的FRR算法在VoIP网络系统中实现QoS性能网络优化的可行性。     

一种自动对称补偿的网络IP时钟误差消除算法

随着移动通信新技术的发展,移动数据传送对时间误差要求越来越高,高精度的网络IP时钟不但能够提升网络吞吐量,同时也能提高网络传输带宽。通过分析网络IP时钟同步时误差的产生机制,提出一种自动对称补偿算法消除时钟同步中产生的误差,并对这种误差算法进行实际验证。测试结果表明,自动对称补偿算法,将大幅度降低IP时钟同步时的误差值,有效地提升了IP时钟的同步能力。     

MPLS网络规划与快速重路由技术的应用

随着宽带业务的迅速发展,传统IP技术和路由协议已经不能满足用户对网络可靠性的需要。在IP城域网的MPLS域中,使用流量分担和网络备份、MPLS快速重路由方法,加快了网络故障恢复的时间,为用户提供了一个高可靠性的骨干网平台。     

一种基于动态阈值的TCP超时重传策略

针对传统的TCP拥塞控制算法在发生超时后存在恢复时间长、收敛性差、网络抖动剧烈等问题,在超时重传策略的基础上提出一种基于动态阈值的超时重传算法。该算法不仅使得网络拥塞处理更为平滑,同时可显著提高数据传输效率。实验表明,新策略能明显降低网络振荡,提高网络吞吐量,有利于网络资源的利用。     

基于Hadoop架构的混合型DDoS攻击分布式检测系统

混合型DDoS攻击采取多种数据类型相结合的方式,具有穿透力强、难以被精确检测的特点,逐步取代了单一类型的DDoS攻击.文章针对混合型DDoS攻击的检测,设计了基于Hadoop集群的分布式入侵检测架构,并提出了一种利用MapReduce模型的多属性融合检测算法.该算法对传统的仅从IP单一角度进行检测的算法进行改进,能够融...     

Impact of Transmission Power Control in multi-hop networks

Many Transmission Power Control (TPC) algorithms have been proposed in the past, yet the conditions under which they are evaluated do not always reflect typical Internet-of-Things (IoT) scenarios. IoT networks consist of several source nodes transmitting data simultaneously, possibly along multiple hops. Link failures are highly frequent, causing the TPC algorithm to kick-in quite often. To this end, in this paper we study the impact that frequent TPC actions have across different layers. Our study shows how one node’s decision to scale its transmission power can affect the performance of both routing and MAC layers of multiple other nodes in the network, generating cascading packet retransmissions and forcing far too many nodes to consume more energy. We find that crucial objectives of TPC such as conserving energy and increasing network capacity are severely undermined in multi-hop networks.     

Graph transformation approaches for diverse routing in shared risk resource group (SRRG) failures

Failure resilience is a desired feature of the Internet. Most traditional restoration architectures assume single failure assumption, which is not adequate in present day WDM optical networks.Multiple link failure models, in the form of shared risk link groups (SRLG’s) and shared risk node groups (SRNG’s) are becoming critical in survivable optical network design. We classify both of these form of failures under a common scenario of shared risk resource groups (SRRG) failures. We develop graph transformation techniques for tolerating multiple failures arising out of shared resource group (SRRG) failures.Diverse routing in such multi-failure scenario essentially necessitates finding out two paths between a source and a destination that are SRRG disjoint. The generalized diverse routing problem has been proved to be NP-Complete. The proposed transformation techniques however provides a polynomial time solution for certain restrictive failure sets. We study how restorability can be achieved for dependent or shared risk link failures and multiple node failures and prove the validity of our approach for different network scenarios. Our proposed technique is capable of improving the diverse route computation by around 20–30% as compared to approaches proposed in the literature.     

Enhancing end-to-end availability and performance via topology-aware overlay networks

This paper proposes a novel overlay architecture to improve availability and performance of end-to-end communication over the Internet. Connectivity and network availability are becoming business-critical resources as the Internet is increasingly utilized as a business necessity. For example, traditional voice and military systems are turning into IP-based network applications. With these applications, even short-lived failures of the Internet infrastructure can generate significant losses.To satisfy these needs, the concept of overlay networks has been widely discussed. However, in the previous studies of overlay networks, a measurable number of path outages were still unavoidable even with use of such overlay networks. We believe that an overlay network’s ability to quickly recover from path outages and congestion is limited unless we ensure path independence at the IP layer. Hence, we develop a simple but effective overlay architecture increasing path independence without degrading performance. The proposed overlay architecture enhances prior studies in the following ways: (1) we deploy overlay nodes considering topology and latency information inside an ISP and also across ISP boundaries; (2) we use a source-based single-hop overlay routing combined with the above topology-aware node deployment; (3) we increase the usage of multi-homing environment at endhosts. In this framework, we develop measurement-based heuristics using extensive data collection from 232 points in 10 ISPs, and 100 PlanetLab nodes. We also validate the proposed framework using real Internet outages to show that our architecture is able to provide a significant amount of resilience to real-world failures.     

Using Network Fault Predictions to Enable IP Traffic Management

IP traffic management is important for the continued growth of the Internet. Several traffic management algorithms exist today. However, to enable these algorithms it is necessary to provide reliable alarms relating to network performance bottlenecks and failures. In this work we propose an algorithm to obtain reliable predictive alarms for network fault conditions. The algorithm is based on modeling network fault behavior. The algorithm has been successfully tested on two production networks. Predictive alarms were obtained for four different types of failures: file server failures, network access problems, protocol implementation errors, and runaway processes. The potential of using this model to do fault classification is also discussed. In addition, it is shown that the proposed algorithm performs better than the majority-vote scheme.     

一种改进的TCP拥塞控制算法

目前,TCP拥塞控制算法作为一种可靠的数据传输被广泛应用在因特网中．在保证网络数据传输可靠性的基础上,数据流之间的公平性是算法设计的重要的性能指标之一．在单瓶颈网络环境下对TCP数据流之间的研究算法已经被提出,但对多瓶颈网络环境下TCP数据流之间的公平性研究至今不多见．因此,根据网络层的显示拥塞指示Marking Relay ECN（explicit congestion notification,ECN）技术,研究了在多瓶颈网络环境下TCP数据流的公平性,提出了一种改进的TCP拥塞控制算法,并使该算法在IP网络中得以实现．仿真结果证明,此算法在多瓶颈网络环境下能使TCP流达到较好的数据流之间的公平性;而且所提出的算法与传统的TCP算法相比,有更高的吞吐量和更快的响应．总之,所提算法性能表现良好．     

云环境下异构无线传感器网络节点调度改进算法

针对大规模传感器网络节点异构性突出、调度困难,传统节点调度算法在大规模传感器网络环境下效率低等问题,提出了基于云计算的节点调度模型,并设计了该模型下的节点调度改进算法。通过将节点算法的执行迁移至云端,由云端调度节点。通过OMnet＋＋对改进算法与云端融合数据处理进行仿真实验表明：改进算法可以有效地延长网络生存周期,并且随着数据量的增加,云端处理融合数据耗时相对平稳。相比较传统节点调度算法,改进算法在能量与耗时指标上表现更优。     

结合负载均衡与A*算法的多AGV路径规划

针对目前大规模应用场景下多AGV运行路网的局部拥塞防止和负载均衡问题,提出了使用负载均衡改进的A*算法进行路径规划的方法。在计算AGV运行代价时,摒弃了传统A*算法只考虑单一运行路程的评价函数,引入了运行路程结合区域负载作为新评价函数的方式。在几乎不增大运行路程的前提下,实现了AGV运行路网的区域负载均衡。采用了单向多入多出以及双向多入多出路网模型进行仿真验证,改变路网规模以及负载系数进行多次仿真实验,结果表明改进算法可以有效地均衡路网负载,极大提高了AGV系统整体运行效率。     

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Hash_tree的多维IP包分类算法

随着各种网络应用的发展,路由器必须能够快速完成对IP数据包的分类,以支持如防火墙、QoS等服务。文章分析了多维IP包分类中Hash算法的应用,在此基础上提出了一种基于Hash_tree的多维IP包分类算法。该算法充分发挥了Hash函数查找快速的特点,对IP数据包的分类能够以T位的线速进行处理,同时算法还具有支持较大的匹配规则集、支持增量更新等特点。