满足本地化计算的集群资源调度策略

将本地化计算分成节点本地化计算和机架本地化计算2个层次,分别称作节点本地化计算和机架本地化计算。结合主导资源公平调度策略DRF和Delay调度约束机制提出一种满足本地化计算的集群资源调度策略DDRF,旨在既能达到一个较高的本地化计算水平,又能保证资源调度的“公平性”。通过数据实验分析了在DDRF调度策略下本地化计算延迟对作业执行效率的影响。     

Traffic and Interference Adaptive Scheduling for Internet Traffic in UMTS

In this paper we propose a scheduling strategy for the radio resources management when transmitting Internet traffic over third-generation systems. More precisely, we consider the UMTS Terrestrial Radio Access Network (UTRAN) Time Division Duplex (TDD) mode standardized by ETSI. UTRAN TDD uses a hybrid solution of code and time division multiple access, called TD-CDMA. In UMTS systems a key issue in developing access methodologies for the available spectrum is an optimal management of the rare radio resources. In this paper we present a fair and efficient scheduling algorithm that adapts its behavior to traffic and interference conditions. Specifically, our scheduling algorithm is able to manage the radio resources taking into account both the traffic fluctuations in the uplink and downlink direction and the variations of the system interference. The goal of our scheduler is the data-throughput maximization for an efficient utilization of available radio resources. The effectiveness of our scheduling algorithm is shown by exploiting analytical tools.     

Scheduling Real-Time Traffic With Deadlines over a Wireless Channel

Recently, there has been widespread interest in the extension of data networks to the wireless domain. However, scheduling results from the wireline domain do not carry over to wireless systems because wireless channels have unique characteristics not found in wireline channels, namely, limited bandwidth, bursty channel errors and location-dependent channel errors.In this paper, we study the problem of scheduling multiple real-time streams with deadlines, over a shared channel. We show that, in general, unlike the wireline case, the earliest due date (EDD) or shortest time to extinction (STE) policy is not always the optimal policy, even if the channel state is perfectly known and EDD is implemented only over channels in a Good state. Here, optimality is measured with respect to the number of packets lost due to deadline expiry. However, for most values of the channel parameters that are of practical interest, we show through analytical and numerical results that the EDD policy over Good channels is nearly optimal. Finally, through simulations, we also show that by combining this policy with fair scheduling mechanisms would result in scheduling algorithms that provide some degree of isolation between the sources as well as provide a natural way of compensating channels that see prolonged error bursts.     

基于非平稳型流量队列模型的Internet流量测量研究

针对大规模细粒度网络流量测量的现实困难,本文引入一种非平稳型流量队列模型NTT,直接对粗粒度的流量采样进行建模.NTT模型是大量活跃的流量队列的迭加,每个队列内部的流量变化过程用分形高斯噪声过程FGN描述,队列的到达过程形成非同构的泊松过程,队列的生存周期服从指数分布.对CERNET主干网的实际流量测量分析验证了NTT模型的有效性,证实了NTT模型可用于基于各种粒度的流量测量的网络行为研究.     

Scalable Network Architecture for Flow‐Based Traffic Control

Many control schemes have been proposed for flow‐level traffic control. However, flow‐level traffic control is implemented only in limited areas such as traffic monitoring and traffic control at edge nodes. No clear solution for end‐to‐end architecture has been proposed. Scalability and the lack of a business model are major problems for deploying end‐to‐end flow‐level control architecture. This paper introduces an end‐to‐end transport architecture and a scalable control mechanism to support the various flow‐level QoS requests from applications.     

基于Hadoop的网络分流和流特征计算

网络流量特征计算是网络流量分析的一个重要步骤,对于海量网络流量数据,并行化计算网络流量特征是高效网络流量分析的重要方法.针对传统单机处理成本高、可扩展性差的问题,提出一种基于MapReduce编程模型的网络流量分析方法,并行实现网络分流和流量特征计算.通过使用Hadoop平台对实际数据进行分析,统计常用网络流量属性特征,实验表明,该方法分析网络流量特征的结果准确可信,且适合分析大流量数据.     

时间敏感网络流量调度算法研究综述

时间敏感网络（Time-sensitive Networking,TSN）是一种新型确定性网络,具有低时延、低抖动等特点,能够满足现代网络传输控制的要求。流量调度是TSN标准中关键技术之一,用于确保流量传输的服务质量。首先对时间敏感网络的发展背景、重要机制、应用场景进行阐述,着重研究5种时间敏感网络流量调度机制,包括基于时间的整形机制、基于信用值的整形机制、循环队列转发机制、帧抢占机制以及异步流量整形机制;然后,分析了流量调度算法的研究现状,归纳和总结了时间触发（Time-triggered,TT）流和事件触发（Event-triggered,ET）流的调度算法,分析了目前流量调度算法存在的问题;最后,指出了TSN流量调度算法的发展方向和趋势。     

Real-Time Traffic Scheduling and Routing in Packet-Switched Networks Using a Least-Laxity-First Strategy

In this paper, we address the problem of transmission scheduling and buffer management at a switch in a high-speed packet-switched network. Future computer networks are expected to carry bursty real-time multimedia traffic with specific time-delay requirements. We propose a technique to schedule competing packets at a switch in a packet-switched network with two objectives—(i) maximizing the number of packets that would reach their destination before their deadline has been reached (ii) minimizing the number of packets dropped in transit in the network. The method is broadly based on the popular least-laxity heuristic in real-time process scheduling and is combined with buffer management at the switch.     

TWDM-PON中带有业务区分的混合资源调度算法

针对时分波分复用无源光网络长距离和广覆盖特性带来往返时延增大,造成高优先级业务时延性能严重恶化的问题,提出带有业务区分的混合资源调度算法.根据网络负载实时调整光网络单元组的波长数以实现资源共享,并动态划分子周期以对不同优先级业务进行区分服务;设计混合资源调度算法,以在线方式填充波长空隙,以离线方式保障资源高效调度.仿真结果表明,所提算法能够满足不同优先级业务的时延要求,保证服务质量,并提高信道利用率.     

Application‐Level Traffic Monitoring and an Analysis on IP Networks

Traditional traffic identification methods based on well‐known port numbers are not appropriate for the identification of new types of Internet applications. This paper proposes a new method to identify current Internet traffic, which is a preliminary but essential step toward traffic characterization. We categorized most current network‐based applications into several classes according to their traffic patterns. Then, using this categorization, we developed a flow grouping method that determines the application name of traffic flows. We have incorporated our method into NG‐MON, a traffic analysis system, to analyze Internet traffic between our enterprise network and the Internet, and characterized all the traffic according to their application types.     

基于IPFIX的网络流量日志系统

针对高速网络海量数据采集、存储和管理问题,分析了传统IPFIX流量日志系统在高速网络中的性能问题,提出了基于IPFIX协议的用户网络流量日志系统体系结构的优化设计,改进了数据聚类和存储算法,包括二元归并方式采集数据以及多层结构的散列算法存储数据。经校园网部署应用证明,可提供万兆链路下用户网络日志详单及准确上网流量计量值。     

Contention‐based geographic forwarding in asynchronous duty‐cycled wireless sensor networks

In asynchronous duty‐cycled wireless sensor networks, it is desirable that the data forwarding scheme is adaptive to the dynamics caused by the uncertainty of sensor nodes’ working schedules. Contention‐based forwarding is designed to adapt to the dynamic environments. In this work, we are interested in the contention‐based geographic forwarding (CGF) for two asynchronous duty‐cycling (ADC) models, which we refer to as uninterruptible ADC (U‐ADC) and interruptible ADC (I‐ADC). We propose a new residual time‐aware routing metric for CGF in the I‐ADC model and present a residual time‐aware forwarding scheme using this metric. We evaluate the performance of CGF in both asynchronous duty‐cycling models. Simulation results show that CGF in the U‐ADC model provides a shorter delivery delay while suffering from a high sender effective duty cycle problem. CGF in the I‐ADC model incurs a very long data delivery delay, but it can achieve a good load balancing among nodes. It is also demonstrated that the proposed residual time‐aware forwarding scheme lowers the effects of the performance degradation caused by the pure asynchronous duty‐cycling operation. Copyright © 2011 John Wiley & Sons, Ltd.     

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。     

Traffic scheduling method based on segment routing in software-defined networking

In order to address the multi-commodity flow problem for traffic scheduling in software-defined networking,a method based on segment routing was proposed.The proposed method pre-computed sets of candidate paths and attributes of these paths for all source-target nodes,and set the requirements of attributes of candidate paths that should be met combined with various demands and constraints of flows,then generated sets of candidate paths for flows.In the proposed scheme,multi-commodity flow model in software-defined networking was simplified based on sets of candidate paths for flows,the difficulty of solving was reduced,the centralized control by the controller and the autonomous control by nodes were supported,the scalability of controller was improved.In addition,how to meet the energy-saving needs of the network was proposed,i.e.,reducing the number of links that could participate in flow forwarding.The performance evaluation results indicate that the proposed method can meet various demands and constraints of flows,improve network performance,and reduce the computational load of solving the problem of traffic scheduling.     

Evaluating the expedited forwarding of voice traffic in a differentiated services network

The Differentiated Services architecture offers a scalable alternative to provide Quality of Service (QoS) to the new multimedia applications in the Internet. This paper aims at evaluating the delay and jitter experienced by voice traffic when handled by the Expedited Forwarding (EF) scheme. The analysis includes the effects of different packet scheduling mechanisms implementing EF and of the voice packet size. We also evaluate how efficiently each type of traffic uses an extra allocated bandwidth and the impact of traffic shaping. The results show that increasing the service rate share allocated to the EF aggregate does not significantly affect the competing best effort (BE) traffic. This holds as long as the BE traffic can use the bandwidth left unused by the EF traffic in idle periods. Copyright © 2002 John Wiley & Sons, Ltd.     

在FPGA中实现交通灯控制系统的设计

伴随着中国经济的快速发展,城市规模越来越大,机动车辆越来越多,给城市交通带来了巨大压力。而传统交通灯控制系统是通过采用中小规模集成电路,或者是采用单片机和PLC等控制芯片进行设计,从而存在控制精度低、电路设计复杂、系统维护困难、成本居高不下等问题。本文采用FPGA的cyclone II芯片,用Verilog HDL硬件描述语言,通过Quartus II软件进行综合仿真,对各功能模块进行设计,然后通过连线组合各底层模块来实现顶层模块设计。     

Earliest Deadline First Scheduling with Active Buffer Management for Real-Time Traffic in the Internet

We studied the problem of QoS guarantee for differentiated services. A two-level hierarchical scheduling framework was deployed to separate QoS metrics. Due to its desirable property of minimizing the maximum packet lateness, the Earliest Deadline First (EDF) scheduling was adopted to provide the in-class scheduling for the time-sensitive traffic. We employed an EDF scheduler combined with an active buffer management scheme (CHOKe) to improve the fairness of resource allocation and to maintain a good delay performance for real-time applications. Simulation results showed that the proposed scheme can achieve a better delay performance and make a more fair bandwidth allocation between the real-time TCP and UDP connections than the First Come First Served (FCFS) scheduling with the drop-tail buffer management which is commonly deployed in traditional IP routers.     

一种新的用于无线Ad hoc网络中视频传输的多路径包调度算法

该文提出了一种新的在无线Ad hoc网络中进行视频传输的多路径包调度算法(MPPA)。该算法充分考虑到视频流传输的特殊QoS要求,针对视频流中的每个数据包进行操作,通过计算将其指定在某条路径上传输。避免了传统多路径传输中的接收端数据包乱序和重新排序的问题,有效地减小了接收端的启动延时和缓冲区需求。同时仿真结果验证了上述理论的正确性。     

基于FPGA的交通信号灯控制系统

为了解决传统交通灯控制系统常采用单片机或PLC等控制芯片所具有的控制不精确、系统外围电路复杂、程序修改不灵活、成本偏高等缺点,利用VHDL硬件描述语言,通过QuartusⅡ软件和以CycloneⅡ系列FPGA为核心的开发板,完成交通信号灯控制系统的设计。该系统具有电路简单、可靠性强、运算速度高、参数易修改等特点。通过软件进行仿真,并在KX_7C5TP型开发板下载模拟,结果表明系统工作正常,控制器能完成预定的设计要求。     

Traffic scheduling method based on centralized control in named data networking

In order to address the global optimization problem for traffic scheduling in named data networking,related works were analyzed,a method based on centralized control was proposed.The proposed method took network performance and communication overhead into account.In the proposed scheme,appropriate nodes would be selected as E-NDN nodes,then the controller calculated the corresponding multi-path forwarding policies and sent them to E-NDN nodes according to the in-network cache,the aggregation of Interest packets,and the traffic demands of popular contents to achieve global optimization.The evaluation results indicate that the proposed method can significantly reduce the maximum link utilization and improve network performance.Simultaneously,the proposed method will not cause a large optimization cost,and communication overhead between the controller and nodes will increase slightly.