抑制BGP路由表增长方法的研究

以增长趋势日益明显的BGP路由表为研究对象,针对在路由表中包含大量前缀长度大于地址分配策略所规定值的路由,基于模式匹配的路由过滤方法,建立了BGP路由前缀扩展列表的路由过滤数学模型,进一步讨论了AS级路由覆盖机制.仿真结果表明,该方法能够有效地滤除前缀长度不符合策略规定的路由,且能满足抑制路由表快速增长的要求.     

路由表前缀结构分析

根据路由表中IP地址前缀之间的包含关系,提出了一种将地址前缀分类的方法,分析了各类地址前缀的增长规律．利用数据结构Trie来描述地址前缀,根据各地址前缀在Trie中的相对关系,将地址前缀划分为不同级别,分析了各级地址前缀的特征,并提出了路由表结构的概念．通过分析近几年路由表的结构探求路由表结构变化的特点和发展趋势．路由表中的地址前缀来源于用户的发布行为,通过分析发布行为对路由表结构的影响,寻找抑制路由表增长的方法．     

基于过滤机制的抑制BGP路由表增长的方法

经过对BGP路由表进行分析,发现在BGP路由表中包含大量前缀长度大于地址分配策略所规定值的路由·给出了一种减缓路由表增长的方法,该方法基于前缀长度对路由进行过滤·对前缀长度大于地址分配策略所规定值的路由,只允许其在指定的距离范围内被通告,一旦该路由穿越了指定数目的AS,它就将被过滤掉,不再被通告·通过修改BGP协议,为其增加一个新的属性来记录被过滤路由的最大通告距离,实现对路由过滤·通过模拟实验证明所给方法可行,对抑制路由表增长效果明显·     

基于下一跳变化的细粒度路由事件识别方法

针对传统基于BGP路由表或更新报文的路由事件识别方法由于路由更新报文噪声以及路由表采集时间间隔的限制,在路由事件识别精度和时间粒度方面存在一定局限性的问题,基于下一跳路由变化矩阵进行路由事件识别,通过BGP路由表和更新报文信息构建细粒度的路由状态变化矩阵,利用矩阵分解方法实现短时隙大规模路由事件的识别,并加以条件限制规避了影响范围较小的本地前缀事件.由于所处理的数据超过1TB,因此构建了近实时批处理的数据分析框架,并通过将此方法运用于已知的路由事件中,实验结果验证了该方法的有效性.     

基于Internet阶层结构的域间路由聚合增强算法

提出了一种域间路由聚合的增强算法,它利用Internet阶层结构特性,以自治系统间关系为依据,强化路由聚合行为并约束可聚合路由的通告范围,给出了原形系统的实现算法·算法所需数据全部来自自治系统内部,没有全局协调数据,并有效回避了聚合行为对负载均衡和链路冗余的负面影响·数据实测和分析显示,算法能有效降低路由表规模,从而缓解当前Internet域间路由表高速增长的局面,加强了Internet的可扩展性·     

Internet路由前缀宣告的特征挖掘与分析

基于大量的历史BGP路由表快照,对BGP路由宣告信息进行深度挖掘.提出了前缀宣告稳定性度量方法,验证了绝大多数路由宣告是稳定的,历史上发生的路由劫持事件都是瞬时的(不具备稳定性);设计了前缀宣告的相似性测度算法,对大量历史BGP路由宣告进行了分析,结果表明大多数大型AS宣告的路由前缀具有自相似性,即,同一个AS宣告的多个路由前缀有一定的连续性.基于以上两个特征,从历史路由信息中可进一步提取前缀宣告的可信集,构造BGP路由宣告的可信知识库,为后续的路由前缀劫持检测和路由安全监测提供依据.     

Chord协议的最优路由表结构

给出了Chord协议路由的形式化描述,将路由过程抽象成一个整数由一个数列受限的线性表示问题.利用Chord的双向边寻求路由表结构的优化,分析并提出了Chord协议的最优路由表结构.给出了基于最优路由表结构的路由算法,证明了3倍数Chord在满环情况下为最优路由表结构.     

一种适用于流匹配的多阶段无冲突归并算法

流匹配算法是准确实现对高速网络中特定流的流量进行测量的关键。RFC算法是相关算法中速度最快的，但它内存消耗很大，预处理运算量大。针对BFC存在的不足，提出了一种多阶段无冲突归并流匹配算法，该算法采用标记桶方法实现前缀匹配的预处理；采用最小区间分隔法实现范围匹配的预处理，同时算法设计了提前丢包。测试结果表明该算法能支持掩码匹配和范围匹配，内存消耗可控，匹配速度可达2Mpps。     

基于地址分配算法压缩路由表

提出一种基于概率的启发式算法对节点地址进行重新编号,该算法可以使得到达一些连续地址的下一跳尽可能的相同,进而再对这些连续地址进行压缩以达到简化路由表的目的.我们利用真实的网络拓扑进行仿真,实验结果表明在维持最短路径路由的前提下,仍然可以压缩到完整路由表的24%,利用这种方法可以极大的简化路由表,以提高网络仿真的规模.     

一种适用于流匹配的多阶段无冲突归并算法

流匹配算法是准确实现对高速网络中特定流的流量进行测量的关键。RFC算法是相关算法中速度最快的,但它内存消耗很大,预处理运算量大。针对RFC存在的不足,提出了一种多阶段无冲突归并流匹配算法,该算法采用标记桶方法实现前缀匹配的预处理;采用最小区间分隔法实现范围匹配的预处理,同时算法设计了提前丢包。测试结果表明该算法能支持掩码匹配和范围匹配,内存消耗可控,匹配速度可达2Mpps。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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