Blocking probability of heterogeneous traffic in a multiratemulticast switch

A multirate multicast switch, which can provide a single uniform switching function for vastly different classes of traffic, is crucial for the successful deployment of integrated broadband networks. We analyze the call blocking probability of heterogeneous circuit switched traffic in a multirate multicast switch using the arrival modulation technique. For the analysis, we introduce two simple traffic models: fan-out heterogeneous traffic and bandwidth heterogeneous traffic. The analysis of two simplified traffic models shows that calls of different characteristics interact in complex yet subtle ways. Our results on fan-out heterogeneous traffic show that the performance gap between large fan-out traffic and small fan-out traffic increases when two types of traffic are mixed. On the other hand, in bandwidth heterogeneous traffic, the performance gap between traffic of different bandwidth decreases. A further investigation indicates that the two types of interactions coexist in general heterogeneous traffic. We conclude the paper introducing several methods to improve the performance of multirate multicast traffic     

一种NetFlow流量分析器的设计

网络流量反映了网络的运行状态,是网络管理领域中重要的研究课题。NetFlow是Cisco公司为实现统计流量而开发的一种协议,使用NetFlow可以方便地进行大规模的流量采集。通过对NetFlow协议原理与功能的分析,设计了一种NetFlow流量分析器。该分析器能够对NetFlow流量数据进行采集和分析,实现网络的异常流量监测、流量计费和综合流量分析,并能及时地发现网络攻击。     

Modeling of split traffic under probabilistic routing

Using a general input traffic class rather than confining it to a specific input traffic model, this letter investigates the split traffic for such a general input traffic class under a probabilistic routing algorithm. Thus the obtained result is applicable for a broad range of input traffic. By way of characterizing the split traffic on each routing path, it is shown that the resultant traffic on each routing path is still the same traffic class with suitable parameter modification.     

一种加密流量行为分析系统的设计研究

随着互联网安全形势的日益严峻,采用流量加密方式进行业务传输的比重越来越大,针对加密流量的监管成为挑战。面对加密流量难以监管的难题,提出了一种加密流量行为分析系统。系统基于加密业务的流量特征,采用机器学习算法,无需解密网络流量就能对流量进行行为分析,实现了加密流量的识别和分类,并对系统进行了试验测试。测试结果显示,该系统可以发现隐藏在加密流量中的攻击行为、恶意行为和非法加密行为,对于安全人员掌握网络安全态势、发现网络异常具有重要意义。     

An efficient modeling and dimensioning approach for integrated streaming and elastic traffic

Recent studies show that both data traffic and real-time traffic grow very fast in wired and wireless networks. To provide better performance guarantee, these applications need efficient network modeling and planning. In this paper, the problem where the total bandwidth of a link is shared by streaming traffic (real time traffic such as voice or video etc.) and elastic traffic (such as data) is studied. Integrating streaming traffic and elastic traffic presents a unique dimensioning problem. This paper considers dimensioning a link to satisfy both quality of service (QoS) requirements for streaming traffic, such as loss probability, and elastic traffic, such as mean waiting (delay) time. The Erlang loss model is applied to streaming traffic and a bursty traffic model is applied to the elastic traffic. Efficient dimensioning algorithms based on classical Markovian models and time-scale decomposition are then proposed. Numerical results show that the proposed methods have good accuracy.     

Effective Traffic Grooming Algorithms in SONET/WDM Ring Networks

Much work has focused on traffic grooming in SONET/WDM ring networks. Previous work has considered many aspects of traffic grooming, including minimizing the number of ADMs, minimizing the number of wavelengths, considering different traffic models, using different network architectures, incorporating switching capability and so on. In this work, we study traffic grooming in unidirectional ring networks with no switching capability under both uniform traffic and non-uniform traffic models to reduce electronic multiplexing costs. Based on the clustering notion, we derive a general and tighter lower bound for the number of ADMs required in traffic grooming under the uniform all-to-all traffic model. This bound reduces to special cases obtained in previous work. We also derive general, tighter, and closed form lower bounds for the number of ADMs required under two non-uniform traffic models: the distance-dependent traffic model and the non-uniform symmetric traffic model. Cost-effective multi-phase algorithms that exploit traffic characteristics are then designed and studied to efficiently groom traffic streams under different traffic models. Our numerical and simulation results show that the proposed multi-phase algorithms outperform existing traffic grooming algorithms by using a fewer number of ADMs. Our algorithms in several cases also achieve the lower bounds derived.     

基于视频序列的交通检测系统

基于人工电视监视的交通检测方法存在检测效率低、实时性差的缺点,提出了基于视频序列的交通参数和交通事件检测系统。将采集和预处理后的视频信号通过DSP处理,检测视频交通参数和交通事件,提取的交通参数和交通事件等分析结果通过TCP/IP网络传输协议传给视频分析识别终端,在视频分析识别终端上存储、显示交通参数与交通事件和视频信息,设置系统参数,同时可以进行查询、检索以及管理交通参数与交通事件。该系统实现了对车流量、车速、抛落物、行人和停车等交通参数与事件的实时性检测。     

CATV宽带网的流量管理系统设计

随着网络技术不断发展，网络管理者希望对网络流量实行有效管理。在分析当前网络流量和CATV宽带网特征的基础上，提出一种CATV宽带网的流量管理方案，并对该方案采用的客户端／服务器／数据库3层分布式结构进行较为详细的描述。     

新型可变分道行驶标志

为了使交通参与者实时了解到道路交通管理措施的变化情况,提高分道行驶标志的服务性和美观度,特研制设计了这种新型的可变分道行驶标志设施。本产品的开发,使得分道行驶标志可以主动发光,在夜晚等外界光线无法满足辨认需要的时候,主动发光的交通标志仍然能够清晰的显示指示内容,而且可以实时显示可变车道的交通管理措施,如：何时可以左转、直行,使驾驶员一目了然。本标志的应用将有效规范行车秩序,缓解交通拥堵,确保安全畅通。     

自相似业务量的流量控制研究

由于自相似性是宽带网络中业务量的一个普遍特性,因此在进行宽带网络管理和流量控制时必须考虑它所带来的影响。目前,有关基于自相似业务量的流控机制的研究已经引起了人们广泛地注意。一些研究表明自相似业务量表现出了与传统模型不同的排队特征。本文围绕业务质量保证和流量控制机制,具体研究和分析了业务量的自相似性质对业务量成形、用法参数控制和呼叫接纳控制等流量控制机制的影响,并得到了一些重要结论。     

基于神经网络的红绿灯识别研究

交通灯的识别对人工智能以及无人驾驶都有着举足轻重的作用,本文研究交通识别中的红绿灯判断,用于改善驾驶员疲劳以及维护交通秩序从而提高驾驶安全系数减少交通事故的发生。通过机器视觉采集红绿灯交通信号图,运用M atlab进行图片处理截取红绿灯区域,提取每张图片的121个像素点RGB值,运用1和2分别表示绿灯和红灯,建立红绿灯样本训练库,通过Matlab自带的数据拟合工具nftool进行神经网络训练,调整训练、验证、测试数据比例,最终得到识别效果较好的神经网络算法。运用样本均值进行测试也能够得到较好的识别。     

十字路口智能交通灯控制系统的FPGA实现

针对现实中越来越严重的城市交通拥堵现象,提出了一种城市十字路口交通信号灯控制与FPGA实现的新方法。解决了各车道车流量不均衡所造成的十字路口交通资源浪费问题,设计的智能交通控制系统利用对相向车道采用不同步的红绿灯信号控制方法,能够减少交通资源浪费,大幅提高十字路口的车辆通行效率。     

Bayonet-corpus: a trajectory prediction method based on bayonet context and bidirectional GRU

Predicting travel trajectory of vehicles can not only provide personalized services to users, but also have a certain effect on traffic guidance and traffic control. In this paper, we build a Bayonet-Corpus based on the context of traffic intersections, and use it to model a traffic network. Besides, Bidirectional Gated Recurrent Unit (Bi-GRU) is used to predict the sequence of traffic intersections in one single trajectory. Firstly, considering that real traffic networks are usually complex and disorder and cannot reflect the higher dimensional relationship among traffic intersections, this paper proposes a new traffic network modeling algorithm based on the context of traffic intersections: inspired by the probabilistic language model, a Bayonet-Corpus is constructed from traffic intersections in real trajectory sequence, so the high-dimensional similarity between corpus nodes can be used to measure the semantic relation of real traffic intersections. This algorithm maps vehicle trajectory nodes into a high-dimensional space vector, blocking complex structure of real traffic network and reconstructing the traffic network space. Then, the bayonets sequence in real traffic network is mapped into a matrix. Considering the trajectories sequence is bidirectional, and Bi-GRU can handle information from forward and backward simultaneously, we use Bi-GRU to bidirectionally model the trajectory matrix for the purpose of prediction.     

Pan-European Optical Transport Networks: An Availability-based Comparison

The traffic to be carried by today's European backbone networks increases very rapidly. An important portion of this traffic consists of data traffic (mainly IP-related). In the future data traffic is expected to become the abundantly dominant traffic type, while voice traffic will only account for a very small portion of the total traffic volume. In this paper, some network topologies for such a pan-European fiber-optic backbone network are presented (more details can be found in [1]). These topologies are compared in terms of the efficiency of the network design both from a cost and capacity point of view and in terms of the availability of the connections routed over this network. In order to be able to assess the network topologies under realistic circumstances, the expected traffic demand is forecasted. This enables to make the comparison for the current traffic volume as well as for the traffic patterns of the future. As not all types of (data) traffic require the same degree of survivability and in order to leverage the total capacity cost of the network design, a distinction is made between different recovery options in the optical layer for the different traffic types considered.     

城市网络交通突发事件应急方案

随着我国城市现代化水平的不断提高和经济的快速发展,交通供需矛盾日渐突出,道路交通网络十分脆弱,一旦发生突发事件,极易引发大面积交通拥堵甚至瘫痪,这将引发严重的社会危害。因此,研究突发事件下城市路网交通应急方案具有重要意义。本文在BA网络模型的基础上重现突发事件下的交通拥堵的形成过程,收集形成过程中产生的各项特征参数,分析交通拥堵的形成机理。最后,提出了应对突发事件下交通拥堵的交通路径策略,从而降低突发事件对网络交通的影响。     

基于车载自组网的动态交通信息的挖掘和利用

动态交通信息系统是智能交通系统中重要的组成部分,作为一种新兴的车辆间无线通信网络技术,车载自组网可有效提高高速行驶车辆间的信息共享能力。文章阐述利用基于车载自组网的交通信息采集和交通事件协同检测算法、大规模海量交通信息的分布式组织和实日寸处理方法、基于位置的交通信息分发协议等技术,构建一个动态交通信息系统,实现改进交通信息系统中的事件检测的准确性和实时性,提高大规模交通信息处理的实时性,改善交通信息分发的针对性。     

On the complexity of Internet traffic dynamics on its topology

Most studies of Internet traffic rely on observations from a single link. The corresponding traffic dynamics has been studied for more than a decade and is well understood. The study of how traffic on the Internet topology, on the other hand, is poorly understood and has been largely limited to the distribution of traffic among source-destination pairs inside the studied network, also called the traffic matrix. In this paper, we make a first step towards understanding the way traffic gets distributed onto the whole topology of the Internet. For this, we rely on the traffic seen by a transit network, for a period of more than a week. As we are still at the stage of understanding the topological traffic distribution, we do not try to model the traffic dynamics. Rather we concentrate on understanding the complexity of describing the traffic observed by a transit network, how it maps onto the AS-level topology of the Internet and how it changes over time. For this, we rely on well-known tools of multi-variate analysis and multi-resolution analysis. Our first observation is that the structure of the Internet topology highly impacts the traffic distribution. Second, our attempts at compressing the traffic on the topology through dimension reduction suggests two options for traffic modeling: (1) to ignore links on the topology for which we do not see much traffic, or (2) to ignore time scales smaller than a few hours. In either case, important properties of the traffic might be lost, so might not be an option to build realistic models of Internet traffic. Realistic models of Internet traffic on the topology are not out of reach though. In this paper, we identify two properties such models should have: (1) use a compact representation of the dependencies of the traffic on the topology, and (2) be able to capture the complex multi-scale nature of traffic dynamics on different types of links.     

基于模拟退火的移动业务分布预测算法

该文提出了一种基于模拟退火的业务分布预测算法,该算法采用模拟退火算法求解超定方程组得到业务密度值。并且提出了业务密度权值的计算方法,从而在用模拟退火算法进行业务分布预测的基础上,给出了利用业务密度权值进行业务分布预测的算法。采用实际统计数据计算结果表明,该方法能够有效地预测业务的分布。     

A multiservice traffic allocation model for LEO satellite communication networks

Modern telecommunication networks are characterized by a heterogeneous mix of traffic classes, ranging from traditional telephone calls to video and data services. Therefore, there is a need to solve the traffic allocation problem with different quality-of-service (QoS) requirements, wherein each traffic demand is fulfilled. This paper investigates the possibility of allocating loaded traffic in a low earth orbital (LEO) satellite network by considering multiservice traffic. Both Poisson and Markov models are used for the incoming traffic, which includes multiservice requirements. By introducing a privilege parameter, a quantum of bandwidth can be reserved for high priority traffic and a better QoS can be given for this traffic. The algorithm performs well for both traffic patterns tested. Simulation results are presented.     

基于流量矩阵估算的流量测量模型

网络流量的测量是流量矩阵估算数据来源的基础。在全面总结了当前的流量测量技术的基础上,从流量矩阵估算的角度提出了一种流量测量模型,引入了适用于流量矩阵估算的测量服务和数据服务的概念,同时对模型的通信机制和数据存储机制进行了探讨,该模型的实现对流量矩阵估算具有非常重要的意义。