网络链路故障浅析

保障网络的正常运行,已成为越来越多人的需求,进而产生了很大的市场,等待人们去开发。网络是一个复杂的系统,其产生的问题更加复杂,主要集中在3个方面：链路故障、配置故障和服务器故障。本文主要就链路故障展开讨论。     

网络链路故障浅析

保障网络的正常运行,已成为越来越多人的需求,进而产生了很大的市场,等待人们去开发.网络是一个复杂的系统,其产生的问题更加复杂,主要集中在3个方面:链路故障、配置故障和服务器故障.本文主要就链路故障展开讨论.     

网络链路故障

这类故障是在网络连接故障中所占比率也是相当高的,它涉及到物理链路和逻辑链路两种。物理链路是指网络布线系统所涵盖的建筑群子系统健筑物间布线）、垂直干线子系统（楼层间垂直布线）、水平配线子系统（同一楼层布线）和工作区子系统（办公室内部布线等）。     

HFC反向链路分析及故障检修流程

1 HFC反向链路网络结构 HFC反向链路由电缆调制解调器(CM)、同轴电缆网络、光节点、反向光纤链路及CM的头端设备(CMTS)等组成,如图1所示.     

基于SDN的链路故障恢复

网络的灾备与故障恢复作为网络安全的一部分,一直以来是人们关注的重点,传统网络缺少自动化的网络故障检测与恢复工具.SDN打破了传统网络设计理念,实现了控制平面和数据平面的分离,并开放了网络的可编程能力,从而提高了网络的灵活性和可管控性.通过SDN技术,自动化的网络故障恢复与检测成为了可能.设计了一种基于SDN的链路故障检测与自动化恢复方案,通过链路发现协议来获得全网拓扑,监控网络链路状态,并通过SDN的集中管控特性和可编程性实现链路故障快速检测和故障恢复.     

园区光纤链路故障的现场排查

光纤以其高带宽、高速度、高抗电磁干扰、低损耗的特点，广泛部署于各类园区网的主干、楼字之间，光纤链路从营运商拓展到了用户园区网内部，FTTx逐步成为现实。但光纤链路由于连接难度大、专用工具成本昂贵，导致故障排查难、维护费用高，绝大多数用户依赖于专业公司维护光纤链路。对于网络管理人员来说，虽然光纤链路的故障率不高，但由于光链路多用于主干，出现故障影响范围广.     

CCSDS空间链路协议体系分析

在CCSDS空间链路层协议上传递IP数据报,实现空间网络和地面网络的无缝连接是未来空地通信发展的主要方向。本文以CCSDS空间链路协议的发展为出发点,分别介绍了常规在轨系统（COS）空间链路协议、高级在轨系统（AOS）空间链路协议和邻近-1（prox-1）空间链路协议的业务类型和功能,分析了协议的层结构、基本原理和关键技术,并对我国开展相关研究提出了建议。     

软件定义网络中链路故障恢复机制研究

软定义网络(SDN)一种革新的网络架构,实现了控制平面和数据转发平面分离,开放了网络的可编程能力,简化了网络管理。随着SDN技术在现实中的广泛应用,其所存在的问题也凸显出来,链路故障就是其中的一个重要方面。文中针对SDN在链路故障方面存在的问题,通过对SDN技术特征和链路故障管理的分析,对现有的SDN中链路故障恢复方法进行了深入剖析,以期对未来在SDN中故障管理机制的研究提供参考。     

Dynamic link sleeping reconfigurations for green traffic engineering

The high volume of energy consumption has become a great concern to the Internet community because of high energy waste on redundant network devices. One promising scheme for energy savings is to reconfigure network elements to sleep mode when traffic demand is low. However, due to the nature of today's traditional IP routing protocols, network reconfiguration is generally deemed to be harmful because of routing table reconvergence. To make these sleeping network elements, such as links, robust to traffic disruption, we propose a novel online scheme called designate to sleep algorithm that aims to remove network links without causing traffic disruption during energy‐saving periods. Considering the nature of diurnal traffic, there could be traffic surge in the network because of reduced network capacity. We therefore propose a complementary scheme called dynamic wake‐up algorithm that intelligently wakes up minimum number of sleeping links needed to control such dynamicity. This is contrary to the normal paradigm of either reverting to full topology and sacrificing energy savings or employing on‐the‐fly link weight manipulation. Using the real topologies of GEANT and Abilene networks respectively, we show that the proposed schemes can save a substantial amount of energy without affecting network performance.     

支持多用户并发访问控制的虚拟网络模型研究

提出了一种与TCP/IP网络兼容的虚拟网络模型,分析了该模型的结构和特点,在模型中引入了多用户并发控制技术,并研究了该模型在网络基础设备和MPLS VPN实验系统实现中的应用。实践表明,基于本模型实现的虚拟路由器以及MPLS VPN实验系统可以同时支持100人以上的多用户并发实验,具有良好的教学实验效果。     

基于自相似业务的网络TCP拥塞控制算法

本文通过对自相似网络模型的分析,采用TCP协议可以直接观测的回环时间（Bound Trip Time)来进行拥塞程度预测,提出一种改进的TCP拥塞控制算法。仿真证明,改进算法在一定程度上提高了网络的整体性能,在自相似程度较高时尤为明显。     

一种基于主动网络技术的改善无线链路上TCP性能的方案

针对TCP在无线环境中性能下降问题,本文提出一种基于主动网络技术的方案,来改善无线链路上的TCP性能.通过网络仿真,证明这种方案具有更高的性能和更多的优点.     

WDM对终端业务和高层协议的影响

主要从基于 WDM网络的网络层及其高层出发 ,描述了以下问题 :业务准备算法以便最小化电复用的代价 ;波长分配算法 ;光层和电层联合保护和恢复 ;光网络拓扑对高层协议 ,如 IP选路、TCP流量控制和多层交换对光网络拓扑的影响。     

网络流量分析中的频繁项监测技术研究

无限数据流中频繁项监测问题定义为对给定输入数据流在任意时刻输出一个当前所有输入数据项中出现频率超过闽值的频繁数据类型及频率值的列表，它对于大规模网络流量分析具有重要意义。本文基于网络报文流分析的应用需求，归纳出一般意义上的报文流分析模型和频繁项监测问题抽象定义，并据此对当前典型的频繁项监测算法进行分析比较。本文还提出一种在有界存储中进行频繁项监测的高精度改进算法，实验结果表明该改进算法满足高速网络报文流的应用需求。     

面向大规模网络的聚集TCP流量模拟方法研究

为平衡大规模网络骨干网上TCP流量模拟的准确性和复杂度,提出模拟接入网出口处的TCP聚集流量,而不从单台主机或会话的层面进行流量模拟。从网络流量的自相似性出发,提出基于应用层和网络传输层自相似的TCP聚集流量模型:在应用层通过聚集多个服从Pareto分布的ON/OFF源模拟生成自相似流量,在网络传输层根据TCP机制实现对应用层流量的聚集传输控制。模拟结果显示,在流量负载比例、流量自相似性以及骨干节点丢包率等方面,模拟结果与采集自某互联网交换中心的实际数据吻合良好,表明了该模型的有效性。     

Network coding based on hyper‐edge decomposition for wireless network with link failures

This paper is concerned with the construction of network coding for wireless network with link failures. Based on hyper‐edge decomposition, for the wireless network, we first construct the hyper‐edge graph, where each node represents one hyper‐edge (consisting of multiple adjacent edges transmitting the same information) of the wireless network. Then we present a heuristic coloration method for the hyper‐edge graph, and a network coding vector allocation scheme based on maximum distance separable code is proposed to effectively overcome some link failures. Copyright © 2014 John Wiley & Sons, Ltd.     

Impact of network failures on the performance degradation of aclass of cluster-based multiprocessors

The impact of increased unreliability of network components on the performance of a cluster-based multiprocessor system (CBMS) is investigated. A generalized model which has been developed for computing the closed-form bandwidth expressions for fault-free as well as faulty systems is discussed. Performance curves are given which illustrate the degradation when unreliability is increased in terms of the number of cluster-network failures. The architecture of the CBMS along with background material for the analysis is described. A special case called private and favorite memory is discussed     

Contribution to future metropolitan access network planning considering link failures in photonic switched networks

Photonic switching for traffic optimization in Metropolitan Access Optical Networks using technologies of optical packet/burst switching (OPS/OBS) seems to be a future-proof solution considering high capacity and the highly variable traffic in these networks. Looking for this future, we propose a study based on the analyze of survivability of traffic unconsidering protection mechanism but considering mesh and ring efficient topologies with node architecture to OPS. The results are obtained through computer modeling and simulation. The main parameters analyzed are as follows: capacity, average number of hops, packet loss fraction, and link utilization for each topology. These parameters are adopted to evaluate the performance of each topology considering failures. Minimum electronic buffering is included at node ingress (client side) to avoid packet loss in the access to the optical layer: high throughput and low latency. It is also observed that optical buffering is not necessary for adequate network performance.