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作为Internet流量模型研究的重要组成部分,IP流流速反映了各种不同应用类型的流量在网络中对实际负载的贡献情况。通过分析和寻找对IP流平均流速产生主要影响的若干关键因子,可以为基于IP流的流量模型提供必要的条件。本文首先分别对IP流的三种主要构成部分:TCP流、UDP流和ICMP流的平均流速从协议分析的角度进行建模,从平均流速模型参数分析中,获得在不同阶段对决定IP流平均流速的若干主要影响因子;然后,使用采集自各种不同时间、不同应用背景和不同负载的大规模高速网络的TRACE作为研究对象,通过试验分析的方法,对所选取的TRACE中不同协议类型的IP流平均流速进行统计分析,检验这些因素在实际网络中在不同流长的情况下对IP流平均流速的贡献,从而验证了本文所提出的IP流平均流速影响因子的可靠性。 相似文献
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Internet流量识别技术研究 总被引:4,自引:0,他引:4
流量识别是指根据网络流以及流中数据报文的某些信息将网络上的流分成若干既定的类别.随着网络的高速化,业务应用和协议日趋复杂,传统的基于端口的流量识别方法已经不够准确,因此各种新的识别方法成为研究热点.本文在介绍流量识别的基本概念、流量识别的评价指标的基础上,对目前正在使用或研究的流量识别方法进行了分析比较,指出了现有各种方法的优点和不足,最后给出未来流量识别技术的发展趋势和研究方向. 相似文献
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《计算机应用与软件》2017,(3)
当链路流量由不同流复合而成时,不同流的短时变化(增大或降低)可以相互中和,使链路上的所有流趋于平稳。当流之间相互独立,链路流量趋于平稳状态。但是,当链路中出现相关流时,该平稳状态将被打破。研究证明许多异常流量发生时会违反流的独立性。基于此,提出了独立流量平稳模型i TSM(independent Traffic Stationary Model),并设计了一种异常流量检测算法。实验证明:针对单链路异常检测,该算法显著优于其他算法的检测效果。 相似文献
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随着数据中心网络规模的迅速增长,网络带宽利用率低下导致的网络拥塞问题日益突出,通过负载均衡提高数据中心网络链路带宽利用率和吞吐量成为了研究热点.如何结合流量特征、链路状态和应用需求进行流量的合理调度,是实现网络链路负载均衡的关键.针对数据中心突发性强、带宽占用率高的大象流调度问题,提出一种面向SDN数据中心网络最大概率路径流量调度算法,算法首先计算出满足待调度流带宽需求所有路径,然后计算流带宽与路径最小链路带宽之间的带宽比,结合所有路径的带宽比为每一条路径计算路径概率,最后利用概率机制选择路径.算法不仅考虑了流带宽需求和链路带宽使用情况,而且全局地考虑了流调度和链路带宽碎片问题.实验结果表明,最大概率路径调度算法能够有效地缓解网络拥塞,提高带宽利用率和吞吐量,减少网络延迟,从而提高数据中心的整体网络性能和服务质量. 相似文献
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软件定义网络将网络的数据层和控制层相分离,具有可编程性强和全局网络视图的优点,这一优点被越来越多的应用于数据中心网络流调度中。然而,数据中心网络中大象流和老鼠流共存的流量特征是流调度技术的一大挑战。对基于流量特征的流调度策略进行了综述,首先梳理了基于软件定义网络的数据中心网络的理论基础,然后对大象流、老鼠流、大象流与老鼠流三个方面的流调度策略进行了分析和总结,并探讨了相比于传统的流调度技术,在软件定义网络架构下基于流量特征的流调度策略的优势。最后针对目前基于流量特征的流调度技术面临的若干主要问题进行了讨论,指出了下一步的研究方向。 相似文献
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Traffic-related emissions are well-known factors in urban environment which may have adverse implication on human health. Estimating vehicular emissions in urban areas provides an understanding of the air pollution caused by traffic. However, existing microscopic approaches cannot simulate the traffic flows and emissions for an entire city and most of the macroscopic approaches are usually highly complex and require priori knowledge about vehicles' route options. This study, therefore, proposes a straightforward and robust approach to simulate vehicular flows and estimated transport emissions at a city scale via a deterministic approach and by applying the Cell Transmission Model (CTM) to simplify the modeling of vehicles' route selections. Under a space-time integrated framework, we firstly simulate a time-dependent distribution of urban vehicular flows and then estimate pollutant emissions of Carbon Monoxide (CO), Nitrogen Oxide (NOx) and Violate Organic Compounds (VOC) for traffic flows on weekday and weekend. Finally, the spatiotemporal patterns of traffic flows as well as traffic emissions were visualized and illustrated under a space-time integrated framework. With accuracies of around 67.4% to 70%, the results demonstrated the feasibility of the proposed approach for estimating city-scale traffic flows and emissions from road transport. 相似文献
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Ryoichi Kawahara Tetsuya Takine Tatsuya Mori Noriaki Kamiyama Keisuke Ishibashi 《Computer Networks》2013,57(6):1560-1576
We consider the mean–variance relationship of the number of flows in traffic aggregation, where flows are divided into several groups randomly, based on a predefined flow aggregation index, such as source IP address. We first derive a quadratic relationship between the mean and the variance of the number of flows belonging to a randomly chosen traffic aggregation group. Note here that the result is applicable to sampled flows obtained through packet sampling. We then show that our analytically derived mean–variance relationship fits well those in actual packet trace data sets. Next, we present two applications of the mean–variance relationship to traffic management. One is an application to detecting network anomalies through monitoring a time series of traffic. Using the mean–variance relationship, we determine the traffic aggregation level in traffic monitoring so that it meets two predefined requirements on false positive and false negative ratios simultaneously. The other is an application to load balancing among network equipments that require per-flow management. We utilize the mean–variance relationship for estimating the processing capability required in each network equipment. 相似文献
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The CONTRAM Dynamic Traffic Assignment Model 总被引:1,自引:0,他引:1
CONTRAM is a computer model of time-varying traffic in road networks, which takes as input the network definition and time-varying demand for travel between a set of origin and destination zones, and outputs the resulting network flows, routes and travel times. It combines a macroscopic time-sliced traffic model with disaggregate dynamic assignment of traffic, so is intermediate between macroscopic equilibrium and microscopic models. The paper details the methods used, including time-dependent queuing which plays a central role, and the treatment of network definition, user classes, road capacities, signals and coordination, vehicle emissions, Intelligent Transport Systems and research lines. 相似文献
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基于Bagging算法和遗传神经网络的交通事件检测 总被引:1,自引:0,他引:1
朱红斌 《计算机应用与软件》2010,27(1):234-236
提出一种集成遗传神经网络的交通事件检测方法,以上下游的流量和占有率作为特征,RBF神经网络作为分类器进行交通事件的自动分类与检测。在RBF神经网络的训练过程中,采用遗传算法GA(Genetic Algorithm)对RBF神经网络的隐层中心值和宽度进行优化,用递推最小二乘法训练隐层和输出层之间的权值。为了提高神经网络的分类能力,采用Bagging算法,进行网络集成。通过Matlab仿真实验,证明该方法相对于传统的事件检测算法能更准确、快速地实现分类。 相似文献
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Recent developments in the IEEE 802.11 standardizations[1] have been successful to offer high-speed data services. Hence, traffic classes (e.g. VoIP or video-conference) with different QoS requirements will be provided in future wireless LANs (WLAN). Sinc… 相似文献
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针对DDOS和蠕虫的特点,提出了一种NeTraMet和QOS相结合的主动防御机制,实现对DDOS和蠕虫经济高效的防治.在蠕虫检测上考虑了无特征蠕虫和有特征蠕虫两种情况;一般基于流量的DDOS检测方法预警时,网络实际已经受到一定程度的攻击而且发生阻塞,为了能够更早预警DDOS攻击,提高网络生存性,在DDOS检测中提出了可疑流量线,当流量达到可疑流量和攻击流量之间时,就启动防御机制,利用路由器的QOS功能,尽量减少攻击流的消耗带宽,维持网络正常服务.最后在NS2中进行模拟验证. 相似文献
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大规模的网络进行动态流量监测的一个优化目标是有效减少观测对象,传统的方法通常根据流在空间的相关性减少测量对象。本文提出了一种基于主成分分析的网络的关键路径发现算法PCAR,它通过分析网络流量的时间和空间的相关性来发现网络中的关键路径。我们用Totem公布的Abliene流量数据检验了PCAR算法的有效性。实验表明,该算法与其它算法相比具有计算复杂性小、误判率低等特点。 相似文献