Internet拓扑抽样探测的偏向性研究

利用traceroute探测网络拓扑结构是研究Internet拓扑属性的主要方法,然而由于这种方法的局限性,使得该方法对正确分析Internet拓扑属性产生很大影响。采用几种网络模型来分析traceroute探测得到的抽样网络属性的偏向性问题,包括节点发现率、边发现率和度分布等。同时针对网络探测参数设置的局限性,还定性分析了在总体抽样粒度不变的情况下,如何设定探测源和目标节点的密度才能达到优化探测网络特征属性的目的。     

一种启发式Internet路由器级拓扑建模方法

针对Internet网络拓扑研究现状,总结了当前Internet所具有的一系列重要属性特征,并对现有基于度分布的网络拓扑模型进行了分析,指出了这些模型在表述Internet路由器级网络时存在的局限性。从实际路由器网络制约因素出发,引入了构建松散网络核心的限制条件和保留节点度属性的重连机制,在增长—优先连接机制的基础上提出了一种启发式非线性优先连接（HNLPA）拓扑建模算法。实验表明,本算法构造的拓扑能够较好地描述Internet路由器级网络特征。     

一种考虑属性权重的隐私保护数据发布方法

k-匿名模型是数据发布领域用于对原始待发布数据集进行匿名处理以阻止链接攻击的有效方法之一,但已有的k-匿名及其改进模型没有考虑不同应用领域对匿名发布表数据质量需求不同的问题.在特定应用领域不同准码属性对基于匿名发布表的数据分析任务效用的贡献程度是不同的,若没有根据发布表用途的差异区别处理各准码属性的泛化过程,将会导致泛化后匿名发布表数据效用较差、无法满足具体数据分析任务的需要.在分析不同应用领域数据分析任务特点的基础上,首先通过修正基本ODP目录系统建立适用于特定问题领域的概念泛化结构;然后在泛化过程中为不同准码属性的泛化路径设置权重以反映具体数据分析任务对各准码属性的不同要求;最后设计一种考虑属性权重的数据匿名发布算法WAK(QI weight-aware k-anonymity),这是一种灵活地保持匿名发布表数据效用的隐私保护问题解决方案.示例分析和实验结果表明,利用该方案求解的泛化匿名发布表在达到指定隐私保护目标的同时,能够保持较高的数据效用,满足具体应用领域特定数据分析任务对数据质量的要求.     

利用直连网络实现可扩展路由器

Internet的迅速发展直接表现为用户流量的迅速增长,这就要求路由器必须提供更大的容量.传统的路由器由线卡和集中式交换网络构成.集中式交换网络只能支持有限的端口数目,而且随着端口数目的增加,调度算法也变得越来越复杂,所以交换网络正成为整个路由器的性能瓶颈.集中式交换网络还是路由器的单一失效点,无法提供令人满意的容错性能.直连网络具有良好的扩展性和容错性.其中,3-D Torus拓扑结构已被成功应用到可扩展路由器的设计当中.但是在实际应用中,3-D Torus结构受到等分带宽的约束,限制了扩展规模.介绍了一种新型的直连网络结构,称为蜂巢式结构.将对蜂巢结构作简单的改动,修改后的拓扑表现出很好的拓扑属性.基于该结构,提出了两类最短路径路由算法.其中,负载均衡的最短路径路由算法较好地利用了直连网络路径多样性的特点,针对均匀随机和Tornado两种类型的流量都表现出较低的分组延时和较高的吞吐量.另就队列长度和单节点调度算法等方面对路由算法的影响进行了讨论.蜂巢结构为可扩展路由器的设计提供了新的选择.     

一种新的匿名路由器问题解决方案

路由器网络拓扑发现在网络拓扑发现中占有非常重要的作用,也是进行网络分析、建模的基础,与网络安全息息相关。本文针对路由器网络拓扑发现中出现的匿名路由器问题,提出了一种新的解决方案——带条件的最大匿名综合。该方法具有不增加网络负担、适用范围广、高效等优点,使得路由器网络拓扑数据更加准确和完整,是一种较好的匿名路由器解决方案。     

复合型路由器级拓扑模型

针对HOT模型的路由器级拓扑在大规模节点下的不足,通过结合自治域级拓扑和路由器级拓扑两种方法,实现了一种复合型Internet路由器级拓扑模型A2R。A2R模型仅依靠路由器规模完成网络拓扑图,解决了自治域拓扑间商业关系推测依靠BGP表的问题,以及自治域间路由连接的问题。实验证明A2R拓扑模型在大规模节点下比其他路由器级拓扑模型拥有更好的性能。     

基于网络行为匿名特征的Tor网络匿名度分析

Tor网络能够提供高质量的匿名服务,目前关于Tor网络匿名度研究主要是从系统设计的角度出发、基于信息熵理论构建静态匿名度模型,这类模型难以动态刻画Tor网络在不同网络环境下的具体网络行为的匿名性,因此本文提出了一种基于网络主体行为匿名特征的动态匿名度模型,改善了现存的匿名度表示方式不适用于大规模匿名网络的情况,并通过增加多种匿名特征的考量提升了匿名度的精确度,为匿名用户对匿名网络的匿名性评估提供理论依据,在此基础上,以Tor网络中常见的拥塞溯源为例,分析了Tor网络在恶意服务器发送爆发式流量拥塞匿名路径并以此特征进行溯源的复杂网络环境下的匿名度。     

基于拓扑结构感知的节点多属性网络映射算法

针对当前节点多属性网络链路映射长度较长、网络请求接受率和收益开销较低的问题,提出基于拓扑结构感知的节点多属性网络映射算法.根据无向图描述节点多属性网络映射问题,采用拓扑结构感知,构建节点多属性网络模型和节点链路映射评测指标,利用回溯算法,计算sumTR值,获得备选网络节点集合.使用子区域作为物理节点映射区域进行资源分配,按照映射优先级排列网络节点依次映射,分析节点多属性,使用最短路径算法,排序跳数最小链路映射,实现节点多属性网络映射.实验结果表明,所提算法能够有效缩短链路映射长度,提高网络请求接受率和收益开销.     

一种新的路由器多址综合方法

网络中路由器拓扑发现是研究网络结构和行为的重要基础。路由器多址综合问题是拓扑发现中的一个难题。在总结现有的路由器多址综合解决方法后提出一种新的方法——邻居-子网综合法。与以往方法相比,该方法可信度提高、效率变快,效果更加明显,较好地解决了路由器多址综合问题。     

PlantWeb大学：无线技术之自组织网络结构

无线拓扑结构 无线网络的拓扑结构指的是网络组件的布置方式.包括无线设备、路由器和网关的物理排列方式,以及数据在他们之间的传输路径.     

pp-mess-sim: a flexible and extensible simulator for evaluatingmulticomputer networks

The paper presents pp-mess-sim, an object-oriented discrete-event simulation environment for evaluating interconnection networks in message-passing systems. The simulator provides a toolbox of various network topologies, communication workloads, routing-switching algorithms, and router models. By carefully defining the boundaries between these modules, pp-mess-sim creates a flexible and extensible environment for evaluating different aspects of network design. The simulator models emerging multicomputer networks that can support multiple routing and switching schemes simultaneously; pp-mess-sim achieves this flexibility by associating routing-switching policies, traffic patterns, and performance metrics with collections of packets, instead of the underlying router model. Besides providing a general framework for evaluating router architectures, pp-mess-sim includes a cycle-level model of the PRC, a programmable router for point-to-point distributed systems. The PRC model captures low-level implementation details, while another high-level model facilitates experimentation with general router design issues. Sample simulation experiments capitalize on this flexibility to compare network architectures under various application workloads     

大型ISP网络拓扑多点测量及其特征分析实例

深入了解Internet拓扑的结构性质有利于更好地设计和发展Internet.由于Internet规模巨大,以及获得完整的路由器级Internet拓扑方面的困难,目前无法研究整个路由器级Internet拓扑.因此,分别研究每个国家级或跨国因特网服务供应商(Internet service provider,简称ISP)网络拓扑结构成为了解Internet拓扑特征的一种可选方法.以中国教育科研网为例,简要描述了多点测量其路由器级拓扑结构的测量结果.分析了该实例拓扑图的节点度分布特征、较大特征值的有关性质以及谱密度分布特征.分析了该实例拓扑图的无符号拉普拉斯谱(SLS)、规格化拉普拉斯谱(NLS)以及群集系数等度量特征.分析结果表明,大型ISP拓扑确实具有某些幂律特征;不同于自治系统级拓扑的情形,对ISP拓扑的节点度补累积分布来说,幂律分布未必拟合得最好;ISP拓扑是一种无标度图,但不符合Barabasi-Albert(BA)生长模型;SLS和NLS具有区分不同的路由器级拓扑结构的能力;Internet路由器级拓扑的发展可能遵循一种不同于BA模型的生长过程.     

Towards experimental evaluation of explicit congestion control

Innovative efforts to provide a clean-slate design of congestion control for future high-speed heterogeneous networks have recently led to the development of explicit congestion control. These methods rely on multi-byte router feedback and aim to contribute to the design of a more scalable Internet of tomorrow. However, experimental evaluation and deployment experience with these approaches is still limited to either low bandwidth networks or simple topologies. In addition, all existing implementations are exclusively applicable to either rate- or window-based protocols and are unable to study performance of different protocols on a common platform. This paper aims to fill this void by designing a unified Linux implementation framework for both rate- and window-based methods that does not incur any interference with the system’s network stack or applications. Using this implementation, we implement and reveal several key properties of four recent explicit congestion control protocols XCP, JetMax, RCP, and PIQI-RCP using Emulab’s gigabit testbed with a ariety of simple yet representative network topologies. Our experiments not only confirm the known behavior of these methods, but also demonstrate their previously undocumented properties (e.g., RCP’s transient overshoot under abrupt traffic load changes and JetMax’s low utilization in the presence mice flows).     

A simulated annealing algorithm for router nodes placement problem in Wireless Mesh Networks

Mesh router nodes placement is a central problem in Wireless Mesh Networks (WMNs). An efficient placement of mesh router nodes is indispensable for achieving network performance in terms of both network connectivity and user coverage. Unfortunately the problem is computationally hard to solve to optimality even for small deployment areas and a small number of mesh router nodes. As WMNs are becoming an important networking infrastructure for providing cost-efficient broadband wireless connectivity, researchers are paying attention to the resolution of the mesh router placement problem through heuristic approaches in order to achieve near optimal, yet high quality solutions in reasonable time. In this work we propose and evaluate a simulated annealing (SA) approach to placement of mesh router nodes in WMNs. The optimization model uses two maximization objectives, namely, the size of the giant component in the network and user coverage. Both objectives are important to deployment of WMNs; the former is crucial to achieve network connectivity while the later is an indicator of the QoS in WMNs. The SA approach distinguishes for its simplicity yet its policy of neighborhood exploration allows to reach promising areas of the solution space where quality solutions could be found. We have experimentally evaluated the SA algorithm through a benchmark of generated instances, varying from small to large size, and capturing different characteristics of WMNs such as topological placements of mesh clients. The experimental results showed the efficiency of the annealing approach for the placement of mesh router nodes in WMNs.     

A simulated annealing algorithm for router nodes placement problem in Wireless Mesh Networks

Mesh router nodes placement is a central problem in Wireless Mesh Networks (WMNs). An efficient placement of mesh router nodes is indispensable for achieving network performance in terms of both network connectivity and user coverage. Unfortunately the problem is computationally hard to solve to optimality even for small deployment areas and a small number of mesh router nodes. As WMNs are becoming an important networking infrastructure for providing cost-efficient broadband wireless connectivity, researchers are paying attention to the resolution of the mesh router placement problem through heuristic approaches in order to achieve near optimal, yet high quality solutions in reasonable time. In this work we propose and evaluate a simulated annealing (SA) approach to placement of mesh router nodes in WMNs. The optimization model uses two maximization objectives, namely, the size of the giant component in the network and user coverage. Both objectives are important to deployment of WMNs; the former is crucial to achieve network connectivity while the later is an indicator of the QoS in WMNs. The SA approach distinguishes for its simplicity yet its policy of neighborhood exploration allows to reach promising areas of the solution space where quality solutions could be found. We have experimentally evaluated the SA algorithm through a benchmark of generated instances, varying from small to large size, and capturing different characteristics of WMNs such as topological placements of mesh clients. The experimental results showed the efficiency of the annealing approach for the placement of mesh router nodes in WMNs.     

基于HCM的可扩展路由器体系结构MER

本文提出了基于层次化协同模型的多维可扩展路由器MER。参考Open Router路由器模型,利用层次化协同模型实现了独立于数据层的控制平台CSP,奠定了开放控制的基础;基于功能插件和抽象插件构造了基于插件的路由器抽象层PRA,分离了控制与转发平面,支持路由器转发平面功能的动态扩展;并举例说明了MER中高效的网络应用控制路由选择机制,体现了直接控制原理,有助于设计更为复杂的控制策略。模拟结果表明,MER具有良好的扩展性,支持网络应用直接控制,为控制平面智能化奠定基础。     

基于TraceNET的多源协作的拓扑测量方法及其应用

面对日趋复杂的网络,网络的管理变得越来越重要,而网络的故障管理、配置管理、性能管理等都离不开网络拓扑。因此如何高效准确地获得网络拓扑,一直是网络拓扑研究中的一个热点和难点。鉴于此,提出了基于TraceNET的多源协作的拓扑测量方法,并且将该方法用于中国科学技术大学（USTC）校园网拓扑测量,结果表明该方法可以高效准确地绑定路由器的别名和发现子网,因此所提方法具有较高的应用价值。基于USTC校园网上高效准确的测量结果,将此测量方法用于中国教育科研网（CERNET）拓扑测量,可以获得的路由器级拓扑为管理和研究Internet提供了较大价值的参考。     

基于自注意力机制和时空特征的Tor网站流量分析模型

不法分子利用洋葱路由器（Tor）匿名通信系统从事暗网犯罪活动,为社会治安带来了严峻挑战。Tor网站流量分析技术通过捕获分析Tor匿名网络流量,及时发现隐匿在互联网上的违法行为进行网络监管。基于此,提出一种基于自注意力机制和时空特征的Tor网站流量分析模型——SA-HST。首先,引入注意力机制为网络流量特征分配不同的权重以突出重要特征;然后,利用并联结构多通道的卷积神经网络（CNN）和长短期记忆（LSTM）网络提取输入数据的时空特征;最后,利用Softmax函数对数据进行分类。SA-HST在封闭世界场景下能取得97.14%的准确率,与基于累积量模型CUMUL和深度学习模型CNN相比,分别提高了8.74个百分点和7.84个百分点;在开放世界场景下,SA-HST的混淆矩阵各项评价指标均稳定在96%以上。实验结果表明,自注意力机制能在轻量级模型结构下实现特征的高效提取,SA-HST通过捕获匿名流量的重要特征和多视野时空特征用于分类,在模型分类准确率、训练效率、鲁棒性等多方面性能均有一定优势。     

A Centrality-measures based Caching Scheme for Content-centric Networking (CCN)

Content-centric networking (CCN) is gradually becoming an alternative approach to the conventional Internet architecture through the distribution of enlightening information (named as content) on the Internet. It is evaluated that the better performance can be achieved by caching is done on a subset of content routers instead of all the routers in the content delivery path. The subset of a content router must be selected in a manner such that maximum cache performance can be achieved. Motivated by this, we propose a Centrality-measures based algorithm (CMBA) for selection of an appropriate content router for caching of the contents. The Centrality-measures are based on the question: ”Who are the most important or central content router in the network for the caching of contents?”. We found that our novel CMBA could improve content cache performance along the content delivery path by using only a subset of available content routers. Our results recommend that our proposed work consistently achieves better caching gain across the multiple network topologies.