基于角色流量管理和个性化带宽分配应用研究

针对目前宽带网接入中对用户流量管理和划分带宽等级难的问题,提出了一种基于宽带接入用户角色的流量管理体系结构.研究了Linux下TC模块实现流量控制和带宽分配的原理,设计了一种基于分类队列的规定,通过把特定的网络用户划分到不同的角色,然后再给不同的角色配置不同的流量控制策略和带宽等级的方法,通过在大型校园网上实际测试证明,该方法能根据需要对不同的用户进行有效地流量管理,规范了网络使用行为,使整个宽带网流量趋于平缓并改善了时间响应特性.     

Linux流量控制管理架构

为了将流量合理地在各处理节点进行调度,优化网络资源的使用,解决网络资源使用的不平衡,分析了Linux核心体系结构、数据传递机制和数据转发过程．介绍了流量分类、队列管理和流量过滤等技术,得到了Linux下流量控制管理架构。通过实验结果证明．基于Linux能有效地进行流量拥塞控制,具有较好的流量管理效果。     

基于Linux的流量控制机制研究

为实现QoS,网络节点必须具有流量控制的能力。Linux从内核2.2版起就增加了对网络QoS的支持,并提供了一套强大的流量控制功能。本文首先分析了Linux的协议体系结构、数据传递机制和数据转发过程,再介绍了流量分类、队列管理、流量整形和流量监测等技术,得到了Linux下流量控制机制的原理。     

基于Linux的一种流量控制方法的研究与实现

随着网络的快速发展,网络中的数据流量不断增长,如何控制网络流量是目前面临的一个难题。本文基于Linux操作系统,利用Netfilter防火墙,结合Linux应用层数据包分类器（L7-filter）,通过修改Linux内核所提供的U32过滤器和fw过滤器接口,将不同的IP按组进行匹配管理,达到流量控制的目的。     

基于ABV的BT流量识别与分类

基于P2P技术的BT应用为人们提供了高效率的网络传输,同时这些应用也消耗了大量的网络带宽.从网络运营的层面来看,要保障网络的正常运行,需要有效地管理和控制不同类别的网络流量,并分配各种网络应用合理的带宽,特别要保证关键业务所需的带宽不会受到BT应用的影响.基于ABV算法提出了一种高效率的BT流量识别与分类方法,通过BT报文的内容分析,正确地识别和分类BT流量,进而可以根据约定的控制规则实现对BT流量的有效控制.通过实验验证了这种BT流量识别和分类方法的有效性和正确性.     

企业局域网流量控制方案的研究与设计

针对目前企业局域网中存在的个别用户频繁使用以P2P技术为基础的在线视频、文件下载等应用,造成局局域网网络带宽被占用,影响到其他用户使用网络的情况,研究并设计了基于局域网的流量控制方案,重点研究了P2P流量的识别技术和基于Linux平台的流量控制方案,并利用开源的Netfilter架构对P2P流量进行精确控制。该方案适用于企业局域网等小型网络,可以实现对网络中不同类型流量的区分与控制,并具有良好的扩展性及可移植性。     

Linux环境下路由器中的网络带宽管理

Linux是目前广泛用于路由设备中的操作系统,而流量管理是这种网络操作系统的一个重要功能.研究了Linux系统的流量管理机制,发现当前Linux系统所采用的在网络接口的出口实现的基于网络包调度的流量管理机制缺乏对于网络带宽在系统范围的全局性的管理,也缺乏对于输入流的网络处理的有效管理和调度,从而造成不必要的CPU资源的浪费.为解决这一问题,提出了一种新颖的网络带宽管理机制,它通过调度网络协议处理所占用的CPU时间来实现带宽管理.这种新的机制将网络带宽的管理和调度从网络接口的出口点转移到处理接收到的网络包的系统软件中断处理程序中,从而克服了原来的流量管理机制的缺点.通过系统实现和对比实验,发现该机制本身给系统带来的负载小于Linux原来的流量管理机制,同时可以提供更好的流量隔离,并且能够有效地节省用于网络处理的CPU资源.     

基于MPLS区分服务的Linux流量控制的实现

Linux提供了强大的流量控制功能来给流量进行分类和区分,该论文针对Linux内核中的流量控制机制进行分析,结合区分服务模型,提出一个针对MPLS区分服务的Linux流量过滤器实现方案.     

Per-IP流量控制方法

通过一条规则达到控制一定范围内的每个IP的相同策略的方法称为Per-IP.在Linux平台上研究了数据包控制框架和流量控制机制,提出了一种Per-IP流量控制的方法.该方法是通过利用Netfilter的模块扩展功能,创建一个可以使用一条规则方便对IP包进行统一限速的模块.系统功能采用内核态和用户态分别实现,限速采用了改进的令牌桶算法.实验结果表明,该方法可以方便有效地控制每个IP的上下行速度.     

面向流量控制的可扩展策略库的设计与实现

Linux提供了一套功能强大的流量控制机制,成为当前实现网络QoS的重要工具.针对制定流量控制方案时带宽划分精度和粒度难以权衡,采用单一队列调度算法实施流量整形效果不尽如人意等问题,提出了基于可扩展策略库的流量控制管理方案,在Linux下设计并实现了可扩展流量控制策略库.介绍了该策略库的3个模块:策略存储实体、出错回滚监控模块和可扩展策略库管理模块.定义了策略的存储格式,将主机、服务、时间、上下行方向等元素综合管理起来.同时提出了结合优先级调度的策略添加、删除、合并的策略管理算法.通过实验分析证明该流量控制管理方案的有效性和实用性.     

区分服务在Linux上的实现

本文给出了Linux流量控制的基本元素的简单介绍，并解释了如何把现有的体系结构加以扩展以支持Diff-Serv。接着，说明了如何使用Linux当前内核里的流量控制的结构来实现Linux支持DiffServ机制。具体地给出了新的组件，分类器，标记器和基于随机早期检测的jjjPHB。我们还描述了该模型的整体结构。     

通用拥塞控制及其在Linux内核中的实现

目前Internet上的拥塞控制采用以TCP为核心的基于窗口技术的端到端（end-to-end)控制方法,具有丢包、响应速度慢等缺陷,造成网络资源的极大浪费。文中提出的通用拥塞控制方法通过对拥塞的早期检测和在相邻节点间交换拥塞控制信息等方法,使网络能对拥塞做出快速响应,从而有效地克服了端到端拥塞控制方法的缺陷,实验结果表明,采用通用拥塞控制的网络在吞吐量和抖动等性能上均优于端到端拥塞控制。     

Location-Dependent Lane-Changing Behavior for Arterial Road Traffic

Lane-changing behavior plays an important role in characterizing urban arterial road traffic dynamics. This paper investigates efficiency-driven and objective-driven motives for drivers to change lanes on arterial roads. The former motive is determined by the circumstances of the surrounding traffic flow, whereas the latter depends on position. A location-dependent lane changing model is then established by weighing the two motives for lane changing. Both continuous and discrete versions of the arterial traffic model are obtained using the LWR (Lighthill–Whitham–Richards) model with the two types of lane changing. Simulations show that the proposed model can reproduce macroscopic traffic phenomena such as spillover and a decrease in the concomitant departure flow, which is the reason for capacity loss. It is concluded that 1) there exists a critical condition under which there is no capacity loss and that 2) a different flow composition could result in a different capacity loss, which varies according to the flow direction. Hence, traffic management and control should take this loss into account.     

RT-ROS: A real-time ROS architecture on multi-core processors

ROS, an open-source robot operating system, is widely used and rapidly developed in the robotics community. However, running on Linux, ROS does not provide real-time guarantees, while real-time tasks are required in many robot applications such as robot motion control. This paper for the first time presents a real-time ROS architecture called RT-RTOS on multi-core processors. RT-ROS provides an integrated real-time/non-real-time task execution environment so real-time and non-real-time ROS nodes can be separately run on a real-time OS and Linux, respectively, with different processor cores. In such a way, real-time tasks can be supported by real-time ROS nodes on a real-time OS, while non-real-time ROS nodes on Linux can provide other functions of ROS. Furthermore, high performance is achieved by executing real-time ROS nodes and non-real-time ROS nodes on different processor cores. We have implemented RT-ROS on a dual-core processor and conducted various experiments with real robot applications. The experimental results show that RT-ROS can effectively provide real-time support for the ROS platform with high performance by exploring the multi-core architecture.     

Can the current generation of wireless mesh networks compete with cellular voice?

Wireless mesh networks are being deployed to provide broadband wireless connectivity to city-wide hotspots. The typical architecture in these deployments thus far is a single-radio architecture: mesh nodes carry only one radio, which is used both to receive the traffic from the clients and to relay this traffic through the mesh to the wired Internet gateway.In this paper, we study the performance of a representative single-radio mesh network both in a live setup and in a laboratory environment. We characterize the performance of different applications (e.g. VoIP), and study some key challenges of mesh networks such as the fairness in bandwidth allocation and hidden node terminal. Finally, we compare the results of the study with traditional cellular networks, and discuss various options to enhance the performance of wireless mesh networks in the future.     

Energy-saving model for SDN data centers

With the development of the Internet, data centers have become vital infrastructures which provide computing, storage and other services for the networks. According to statistics, data centers consume large amount of electricity all around the world. In most cases, the majority of network devices in data centers are relatively idle, resulting in a waste of energy. Software defined network (SDN) was proposed by UC Berkeley and Stanford University around 2008, which allows the administrators to manage the network and set configurations through abstraction of lower level functionality. It also separates the control plane and the data plane, so administrators can control the network traffic through centralized controller instead of access to physical devices. This paper discusses the energy-saving model in data center networks based on SDN. We propose two different energy-saving algorithms, which can be applied to different data centers. Through centralized management and preprocessing traffic by SDN, we get better energy efficiency and reduce the energy cost by 30–40 %. To the best of our knowledge, this is the first work on energy saving in SDN architecture which provides two different algorithms that can be applied in different scenarios.     

A video streaming application for urban traffic management

Urban traffic control systems have based their technological infrastructure both on advanced analog close-circuit television systems (CCTV) and point-to-point links, providing difficult-to-scale and very expensive systems. The main goal of an urban traffic monitoring system is to capture, send, play and distribute video information from the streets of a certain city to a management centre where it is processed by different services. Current digitalization process of video networks, and the research carried out in the field of streaming media, has led vendors to present proprietary hardware and software solutions resulting in a strong dependency by their customers. This work presents an open urban traffic control system based in commercial off-the-shelf (COTS) philosophy for hardware and software components, as well as open source and standardized protocols. The existence of open standards for video encoding and protocols for streaming media transmission over IP networks has led to the proposal of such a system. The proposed system is a suitable solution in terms of scalability, cost, interoperability and performance for traffic control systems. Furthermore, its architecture can be easily adapted to other video applications and tools like command and control, surveillance or security systems for military and civilian applications.     

Threshold configuration and routing optimization for PCN-based resilient admission control

Pre-Congestion Notification (PCN) in IP networks uses packet metering and marking within a PCN domain to notify its egress nodes whether link-specific admissible or supportable rate thresholds have been exceeded by high-priority traffic. Based on this information simple admission control and flow termination is implemented. The latter is a new flow control function and useful in case of overload through high priority traffic which can occur in spite of admission control, e.g., when traffic is rerouted in failure cases. Resilient admission control admits only so much traffic that admitted traffic can be rerouted without causing congestion on backup paths in case of a likely failures, e.g., single link failures.We propose algorithms to configure the link-specific PCN rate thresholds such that resources are utilized efficiently and fairly by competing traffic aggregates while meeting resilience constraints. This is done for the single and dual marking PCN architecture whereby the single marking case is more demanding since it requires that the supportable rate is a fixed multiple of the admissible rate on all links within a single PCN domain. Furthermore, we derive objective functions to optimize the underlying routing system for both cases. Our performance results for various network types show that the dual marking PCN architecture leads to significantly better resource efficiency than the single marking PCN architecture.