因特网上的MPLS流量工程

主要讨论因特网上多协议标记交换（MPLS）流量工程，首先简述了MPLS、约束路由技术以及增强链路状态内部网关协议，然后讨论了设计MPLS流量工程系统的主要问题，接着说明了配置MPLS流量工程系统的步骤，最后阐述了MPLS网络的QoS机制。     

MPLS的流量工程及QoS保证

作为下一代网络的关键技术 ,多协议标签交换MPLS(MultiprotcolLabelSwitching)技术以其流量工程特性及QoS保证在IP网中扮演越来越重要的角色。本文简要介绍了MPLS的网络结构及其流量工程与QoS保证的原理与实现。     

IP网络QoS的实现机制分析

在详细分析比较各种IP QoS服务模型的基础上,阐明了基于MPLS的IP组网模式在支持QoS、流量工程等方面的优势,指出MPLS DiffServ是未来解决IP QoS的发展趋势。     

基于ATM的MPLS流量工程研究

研究了基于ATM的MPLS,重点研究和分析了具体实现MPLS流量工程的ATM流控措施、使用约束路由的标记分发协议、路由协议,为MPLS流量工程的具体实施提供了参考。同时研究了MPLS多协议标记交换技术融合IP路由技术、ATM的QoS（Quality of Service）及交换技术,使得流量工程模式可以部署在基于IP的网络,其中包括ATM网上承载IP业务的模式。     

基于OPNET仿真的MPLS流量工程的分析

MPLS被认为是下一代IP骨干网络技术,而流量工程是合理使用网络资源保障QoS的关键。支持MPLS的路由器可以使用新的机制实现流量工程。该文基于目前功能最大的网络仿真工具OPNET,进行基于MPLS的流量工程的仿真,并对仿真结果进行比较和分析。     

MPLS向网络边缘演进

本文讨论了MPLS在网络演进过程中的重要作用和在多业务综合网络中的主要功能比如：QoS，流量工程、流量保护等。针对MPLS在接入网中的应用特点，分析了一个基于MPLS技术的接入网解决方案。     

MPLS网络带宽配置的Hose模型及优化算法

服务质量(QoS)和流量工程(TE)是在当前网络中提供实时应用业务的两项重要技术.多协议标记交换(MPLS)在IP网QoS提供和TE实现中起了关键作用.本文首先介绍了Hose模型,分析了MPLS网采用该模型提供多种VPN业务的流量工程问题,提出了MPLS网采用该模型提供多种VPN业务的最优带宽配置算法,给出了相关的优化模型和实例,实例优化结果表明该方法能在确保业务的QoS要求并且网络开销增加较少的情况下,有效地均衡网络负荷.     

感知区分服务的MPLS流量工程技术研究

区分服务(Diffsevr)通过服务分级定义了流量的逐跳行为(PHB);流量工程(Traffic Engnineering)实现转发路径的优化。感知区分服务的MPLS流量工程(Diffsevr-aware MPLS Traffic Engnineering,简称DS-TE)将MPLS的区分服务与流量工程结合在一起,使其能够感知彼此的存在。DS-TE提出了基于类的资源分配思想,可以根据业务的类型,细粒度地建立交换路径,进一步保证了QoS。     

浅析多协议标记交换MPLS

本文介绍了MPLS的发展、基本原理以及MPLS在流量工程、QoS、VPN、SIN模式、组播等方面的优势、实现方式和特点。     

感知区分服务的MPLS流量工程技术研究

区分服务（Diffsevr）通过服务分级定义了流量的逐跳行为（PHB）；流量工程（Traffic Engnineering）实现转发路径的优化。感知区分服务的MPLS流量工程（Diffsevr-aware MPLS Traffic Engnineering，简称DS-TE）将MPLS的区分服务与流量工程结合在一起，使其能够感知彼此的存在。DS-TE提出了基于类的资源分配思想，可以根据业务的类型，细粒度地建立交换路径，进一步保证了QoS。     

一种新的对称CDMA系统中非对称业务下的呼叫允许控制策略

未来无线多媒体网络将以分组技术为基础,支持多种业务的传输,业务的QoS保证将受到一定的挑战.各运营商也将针对自己所服务的对象特点,定义各类业务的QoS等级,来提供具有不同QoS要求的业务.因此,呼叫允许控制(Call Admission Control,CAC)策略将要以分组业务为主要对象,即既要在充分利用系统资源的基础上保证各业务的QoS要求,又要适应各运营商之间的不同需求.因此本文提出一种新的对称CDMA系统中非对称业务下基于动态QoS保证的CAC策略.各运营商可根据自己的要求定义各业务的QoS等级.由于业务的不同特性,使得网络中上行链路和下行链路的业务呈现不对称性,为避免资源的浪费,将根据网络中的资源占有情况动态的地分配上行和下行链路中的资源.仿真结果表明,该策略可以自适应地保证各业务的QoS要求,提高了业务间的公平性和系统资源的利用率.     

基于智能业务识别的可信路由研究

本文研究并提出了基于智能业务识别与控制的可信路由架构.该架构根据动态配置的安全/Qos策略,在智能业务分类与识别的基础上,标记数据包,执行业务流量自适应调节与控制,并采用队列管理和调度管理,实现可信Qos路由.此外,本文综合了端口匹配法的简单、快速、复杂度低和灵活性好,净荷分析法的精确有效,以及流量特征分析法可扩展性好等特点,提出并建立了实时智能网络业务分类系统.该系统具有较高精度、低计算复杂度、良好的可扩展性、早期检测和鲁棒等优点,是高速链路可信路由的前提和保障.     

A Fair and QoS-Aware Resource Allocation Scheme in UWB WPANs with WiMedia Distributed MAC

Merits of distributed medium access control specified by WiMedia Alliance such as distributed nature and high data rate make it a favorite candidate standard for high rate wireless personal area network. However, the current WiMedia MAC standard has not considered supporting Quality of Service (QoS) even though QoS parameters such as a range of service rates are provided to each traffic stream (TS). Therefore, we propose a fair and QoS-aware resource allocation method that provides a fair and maximized QoS for all TSs according to the current traffic load condition and differentiates SoQ among different QoS classes while guaranteeing fairness of SoQ within a QoS class in a fully distributed manner. Even in case that the traffic load varies, each device independently recognizes the changes and calculates fair and maximum allowable service rates for TSs. From the simulation results, it is proven that the proposed method achieves high capacity of TSs and fair QoS provisioning under various traffic load conditions.     

The Threats of Infrastructure Obsolescence to Smart Grid: A Case Study

Network convergence has vital importance due to limited network resources. Though it decreases network cost, it also reduces Quality of Service (QoS) as well. Due to the increase in real-time network applications, such as video conferencing and voice over IP calls, there is a need to achieve fairness in user's demand through QoS. QoS measurement tasks are more challenging and increased network losses in infrastructure less network. QoS is not yet implemented in Wireless Local Area Network (WLAN) using Software Defined Network (SDN). We have proposed a model to support QoS in WLAN using SDN architecture for real-time traffic. It is efficiently utilizing bandwidth and reducing flow starvation due to centralize control. We named it, an Adaptive QoS model. This model allocates queues dynamically to flows using real-time traffic analysis in SDN architecture. A specific queue is allocated to a specific type of traffic. Flows are dynamically switched based on the increase in traffic demand if other queues are under-use. We achieved handsome improvement in Adaptive QoS model rather than a standard QoS model in terms of throughput and losses.

     

Hub‐polling‐based IEEE 802.11 PCF with integrated QoS differentiation

IEEE 802.11 is one of the most influential wireless LAN (WLAN) standards. Point coordination function (PCF) is its medium access control (MAC) protocol with real‐time traffic (rt‐traffic) quality‐of‐service (QoS) guarantees. In PCF, it is very likely that non‐real‐time traffic (nrt‐traffic) will use the contention free period (CFP) that should be dedicated to traffic having higher priority such as rt‐traffic. Therefore, a modified PCF protocol called MPCF, which is based on hub polling and an integrated QoS differentiation, is presented in this paper. With the integrated QoS differentiation, MPCF can prioritize bandwidth requests according to service classes and QoS requirements. With hub polling, MPCF can reduce the bandwidth for control frames and improve the network throughput. A simple and accurate analytical model is derived and presented in this paper to calculate the system throughput of MPCF. Simulation results show that MPCF protocol is much better than PCF in terms of system capacity and rt‐traffic QoS guarantees. Copyright © 2008 John Wiley & Sons, Ltd.     

支持多优先级QoS的业务量疏导算法

针对当前业务量疏导研究中很少涉及的QoS约束的问题,提出并研究了一种支持多优先级QoS的业务量疏导算法（Differentiated Traffic Grooming Algorithm,DTGA）,该算法综合考虑了对不同等级业务QoS和网络资源利用率的优化。与目前实用的WDM光网络业务量疏导算法的性能仿真对比表明,DTGA能有效地降低高服务等级需求业务的阻塞率和节省网络资源。     

A survey of adaptive bandwidth control algorithms

In packet-switched network traffic management and control, efficiently allocating bandwidth to provide quantitative packet-level QoS to aggregate traffic has been difficult due to unpredictable, unknown statistical characteristics of the aggregate traffic. With inaccurate traffic information, using static bandwidth allocation results in the network being underutilized, or the QoS requirement not being satisfied. An alternative is to use Adaptive Bandwidth Control (ABC), whereby the allocated bandwidth is regularly adjusted over the packet-level time scale to attain a given QoS requirement. This paper provides a literature review of ABC algorithms that guarantee aggregate traffic packet-level QoS metrics, such as the average queue length, packet loss, and packet delay. We describe different ABC algorithms, identify their advantages and shortcomings, and provide some comparative performance evaluation results. Open issues in ABC for future research directions are also discussed.     

QoS约束的链路故障多备份路径恢复算法

链路故障的恢复,不仅仅是选择一条连通的备份路径问题,还应考虑网络业务故障恢复过程中的QoS需求。针对此问题,该文基于多备份路径策略,构建概率关联故障模型和重路由流量丢弃量优化目标。并基于该优化目标,以业务的QoS需求为约束,建立故障恢复问题的数学模型,提出一种QoS约束的链路故障多备份路径恢复算法。该算法构建单条备份路径时,以最大程度地减少重路由流量丢弃为目标,并采用改进的QoS约束的k最短路径法进行拼接,且给与高优先级链路更多的保护资源。此外还证明了算法的正确性并分析了时间空间复杂度。在NS2环境下的仿真结果表明,该算法显著提升了链路故障恢复率和重路由流量QoS满足率,且QoS约束条件越强,相较于其它算法优势越明显。     

从公路网的视角看IP QoS

本文从公路网的视角重新认识IP QoS问题,提出了互联网所需要和所能提供的是一种适合的、相对的、统计意义上的IP服务质量保证能力,并分析目前在网络实际应用中有助于改善IP QoS一些方法的成功之处,包括提高网络的硬件通行能力、提供差异化的服务质量保证、提高网络对流量的控制能力,最后讨论公路网对IP QoS下一步研究的一些启示.     

Soft QoS in Call Admission Control for Wireless Personal Communications

In wireless multimedia communication systems, call admission control (CAC) is critical for simultaneously achieving a high resource utilization efficiency and maintaining quality-of-service (QoS) to mobile users. User mobility, heterogeneous nature of multimedia traffic, and limited radio spectrum pose significant challenges to CAC. QoS provisioning to both new calls and handoff calls comes with a cost of low resource utilization. This paper proposes a CAC policy for a wireless communication system supporting integrated voice and dataservices. In particular, soft QoS (or relaxed target QoS) is incorporated in the CAC policy to make compromises among different objectives.Numerical results are presented to demonstrate that (a) in dealing with the dilemma between QoS satisfaction and high resource utilization, how the resource utilization efficiency can be increased by introducing soft QoS; and (b) in accommodating different types of traffic, how the QoS of low priority traffic can be improved by specifying soft QoS to high priority traffic.