基于以太网的IP接入网络的QoS技术研究

接入网的QoS机制是实现NGN中端到端的QoS保证的重要因素，而以太网是最为主要的接入网技术。本文讨论了ITU NGN专题组NGNFG中关于基于以太网IP接入网络的QoS的控制体系结构的研究进展，在基于以太网IP接入网络的定义和参考模型中分析了基于以太网IP接入网络的QoS问题，本文阐述了基于以太网的IP接入网络的支持动态和每个会话控制的QoS控制过程和提出了有关的接口以及它们的需求。     

锐捷网络RG-R3660构建多业务智能平台

在今天的网络应用中,企业网已经成为一个包含语音、图像与数据业务的综合性平台,这就要求企业级路由器、尤其是汇聚层路由器拥有更好的QoS功能、支持语音视频等新兴应用.针对这种应用趋势,锐捷网络(原实达网络)定制了模块化企业级路由器产品--PG-R3660.RG-R3660采取可拆卸的模块化结构设计,并采用锐捷自主产权的RGNOS操作系统,具有高处理能力和高接入密度;同时,它支持全面的VoIP、良好的VPN以及丰富的QoS等功能,既可以在中小型企业网中担当核心路由器,也适用于在大型网络中担当汇聚层路由器.     

路由选择协议与VLSM子网设计

随着网络应用的日益广泛,接入网络和边缘网络的需求也更加复杂多样,企业为了开展电子商务,必须实现与Internet的互联,路由器是实现这一互联的关键设备。路由器可以为企业提供越来越多的智能化服务,包括安全性、可用性和服务质量(QoS)等。下面结合实践经验,讨论Cisco路由器的路由选择协议与VLSM子网设计。     

IEEE 802．11无线自组织网络服务质量机制研究

IEEE 802．11无线自组织网络中采用随机方式接入无线信道，提供服务质量(QoS）保证难度很大。目前已提出媒体接入层机制以改进无线自组织网络服务质量。但单纯的媒体接入层服务质量机制同样具有较大局限性。本文系统分析比较了不同无线自组织网络环境下媒体接入层和网络层服务质量机制的性能，基于上述分析结果，提出一种跨层自组织网络服务质量机制。     

地区电力数据通信网若干问题的探讨

电力数据通信网是电力公司生产、管理系统联网的综合业务承载平台.本文从网络安全和业务接入等方面对泉州电力数据通信网在建设和应用中的若干问题进行讨论.网络安全主要从路由器设备安全、网络路由安全及访问控制等方面进行了探讨,业务接入方面对接入方案、QoS部署等若干问题进行了分析.     

路由器可拆卸——锐捷网络推出模块化RG-R3660

目前的企业级路由器、尤其是汇聚层路由器在朝着提供更高的QoS支持功能,并且还要支持语音、视频等多业务应用的方向发展。针对这种应用趋势,5月底,锐捷网络(原实达网络)宣布推出模块化企业级路由器产品RG-R3660。该产品采取可拆卸的模块化结构设计,并采用锐捷自主产权的RGNOS操作系统,具有高处理能力和高接入密度。同时,该产品还全面支持VoIP、VPN、QoS等功能,为企业网构建智能化多业务平台。支持弹性业务组合RG-R3660设计了6个网络/语音模块插槽来共同支持高密度的网络与语音模块,然后保证这些功能模块完全符合各类网络标准,以提…     

支持路径选择与快速切换的移动网络接入路由器安全Mesh(英文)

性能一直是网络移动投入实际运营的瓶颈所在,而现有认证机制产生的延时使之雪上加霜.文中为多穴嵌套移动网络的接入路由器Mesh引入一种高效的双向认证机制,基于此提出最优路径选择算法和接入失效快速恢复算法,以提高移动网络的整体性能,尤其是延时的降低.文中,基于固定AAA基础设施和动态可信邻居的安全关联转移被用于减少路由器Mesh的认证延时,其行为评估机制降低了路由器攻击或欺骗对路径评价的影响;基于顶层接入路由器网络前缀的移动路由器转交地址配置被用于消除嵌套接入环境下的多角路由和隧道嵌套问题,而必要时临时隧道和反向路由头可以替代随切换而来的绑定过程以缩短切换延时,最后通过接入路由器评价生成到达Internet的最优路径.定性分析与仿真分析表明,由于异域网络间建立安全关联的高效性,加上行为评估、路径评估和快速切换产生的性能优化作用,文中的安全Mesh在吞吐量、传输延时和切换延时方面较同类方案更加高效.     

RIDSI:一种融合SDN和兴趣域划分的ICN路由机制

信息中心网络(Information-Centric Networking,ICN)中的服务质量(Quality of Service,QoS)路由是分布式的,无法感知其它路由器缓存的内容,因此,基于软件定义网络(Software Defined Networking,SDN)的全局视图和集中控制功能,本文提出了一种基于兴趣域划分的ICN路由机制.这种机制旨在减轻内容节点的负载、提高路由成功率和提高PIT命中率.首先,本文提出了基于SDN的ICN网络模型,即软件定义信息中心型网络(Software Defined Information Centric Networking,SD-ICN)模型和QoS评价模型.然后,采用蜂群算法将网络中的路由器划分到不同的兴趣域.最后,基于改进的QoS依赖多播路由(QoS Dependent M ulticast Routing,QDM R)算法计算满足多个兴趣请求的转发路径.仿真实验结果表明,本文提出的路由机制与对比机制相比在路由成功率、平均路由延迟、负载均衡度等方面都具有较好的性能.     

SOHO光路由器的设计实现

随着信息技术的发展,SOHO光路由器提供了更加便捷、快速的接入手段。同时路由器作为内部网络与外部网络之间通讯的关键设备,对网络的安全有着重要的作用。目前市场上的路由器基本采用电口(以太网RJ45口)接入形式,而在光纤接入网络快速发展和普及的时代,非常有必要开发一款光纤接入形式的路由器,以满足光纤接入网络发展的需求。叙述了光路由器的总体系统设计、要实现的性能、功能和主要技术指标。     

MPLS流量工程及其形式化研究

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，通过在线或离线的算法计算LSP确保QoS．在综述了MPLS应用于流量工程的优势、QoS路由、接纳控制、重新路由、容量设计和部署等问题及其形式化研究等方面的最新工作的基础上，对几种MPLS QoS路由的算法进行了对比和总结，并分析了进一步的研究方向和问题．     

MHWSN中保证混合业务QoS的跨层调度算法

针对中高速传感器网络中混合业务QoS（Quality of Service）要求,跨层考虑物理层和数据链路层参数,提出了一种保证混合业务服务质量的调度算法AM-LWDF。该算法同时考虑时延优先级和吞吐量优先级,在满足实时业务QoS约束的前提下,以最大化系统吞吐量为目标建立了相应的优化模型,对实时业务能够满足时延较小的要求,对非实时业务满足吞吐量较大的要求。仿真结果表明,该调度算法可以灵活地在时延和吞吐量之间取得满意的折衷,并保证不同类型业务用户间的公平性。     

Globally Synchronized Frames for guaranteed quality-of-service in on-chip networks

Future chip multiprocessors (CMPs) may have hundreds to thousands of threads competing to access shared resources, and will require quality-of-service (QoS) support to improve system utilization. This paper introduces Globally-Synchronized Frames (GSF), a framework for providing guaranteed QoS in on-chip networks in terms of minimum bandwidth and maximum delay bound. The GSF framework can be easily integrated in a conventional virtual channel (VC) router without significantly increasing the hardware complexity. We exploit a fast on-chip barrier network to efficiently implement GSF. Performance guarantees are verified by analysis and simulation. According to our simulations, all concurrent flows receive their guaranteed minimum share of bandwidth in compliance with a given bandwidth allocation. The average throughput degradation of GSF on an 8×8 mesh network is within 10% compared to the conventional best-effort VC router.     

A multi-layer experimental study of multimedia and QoS communication in wireless mesh networks

A significant issue in Mesh networks is to support multimedia transmissions while providing Quality of Service (QoS) guarantees to mobile users. For real-time multimedia streaming, unstable throughput or insufficient bandwidth will incur unexpected delay or jitter, and it remains difficult to provide comprehensive service guarantees for a wireless mesh environment. In this paper, we target the problem of providing multimedia QoS in wireless mesh networks. We design and implement a campus test-bed for supporting multimedia traffic in mobile wireless mesh networks, and investigate in detail some possible improvements on a number of layers to enable multimedia transmission over wireless networks with QoS support. We first study a number of improvements of some existing routing protocols to support multimedia transmissions. Some new admission control and rate control mechanisms are studied and their performance gains are verified in our experiments. In our new cross-layer adaptive rate control (CLARC) mechanism, we adaptively change the video encoder’s output bit rate based on the available network bandwidth to improve the quality of the received video. We also design a mobile gateway protocol to connect the MANET to Internet and a wireless LAN management protocol to automatically manage WLAN to provide some QoS.     

Modeling and performance analysis for IPv6 traffic with multiple QoS classes

This paper focuses on the modeling and performance analysis for IPv6 traffic with multi-class QoS in virtual private networks (VPN). The multi-class QoS is implemented on differentiated service basis using priority scheme of 4 bits defined in the packet header of IPv6. A VPN-enabled IP router is modeled as a tandem queuing system in which each output link consists of two parallel priority output queues. The high-priority queue is used to carry the delay sensitive traffic while the low-priority queue is used to carry the delay insensitive traffic. On the other hand, multiple thresholds are implemented in each queue, respectively, for packet loss priority control. The performance analysis is done using fluid flow techniques. The numerical results obtained from the analysis show that the differentiated service based on the priority schemes defined in IPv6 is able to effectively satisfy the multi-class QoS requirement for supporting multimedia services in VPN. The performance trade-off between the delay sensitive traffic and delay insensitive traffic in terms of traffic throughput, packet loss probability and end-to-end delay in VPN networks is presented.     

无线Ad Hoc网络QoS路由协议研究的进展与展望

无线ad hoc网络是一种无固定通信设备支持、节点可自由移动的多跳全分布式无线网络。无线ad hoc网络的应用环境以及与Internet的互连要求它必须提供一定的服务质量(QoS)保证，而QoS路由协议是无线ad hoc网络支持QoS的一个关键理论和技术，也是目前的一个研究热点。本文回顾了近年来国内外在无线ad hoc网络QoS路由协议研究方面取得的研究成果，对已有的无线ad hoc网络的QoS路由协议进行了分类．并对它们作了较全面的概括。总结和深入的比较分析，系统阐述了在无线ad hoc网络中实现QoS路由协议时需要考虑的因素，指出了亟待解决的问题和今后的研究方向。     

Quality-of-service adaptation in distributed multimedia applications

High-speed networks and powerful end-systems enable new types of applications, such as video-on-demand and teleconferencing. Such applications are very demanding on quality of service (QoS) because of the isochronous nature of the media they are using. To support these applications, QoS guarantees are required. However, even with service guarantees, violations may occur because of resources shortage, e.g., network congestion. In this paper we propose new adaptation approaches, which allow the system to recover automatically, if possible, from QoS violations (1) by identifying a new configuration of system components that might support the initially agreed QoS and by performing a user-transparent transition from the original configuration to the new one, (2) by redistributing the levels of QoS that should be supported, in the future, by the components, or (3) by redistributing the levels of QoS that should be supported immediately to meet end-to-end requirements based on the principle that (local) QoS violation at one component may be recovered immediately by the other components participating in the support of the requested service. The proposed approaches, together with suitable negotiation mechanisms, allow us (1) to reduce the probability of QoS violations which may be noticed by the user, and thus, to increase the user confidence in the service provider, and (2) to improve the utilization of the system resources, and thus to increase the system availability.     

Spectral efficiency of cognitive radio networks under interference constraint and QoS guarantees

We study the problem of maximizing spectral efficiency of cognitive radio network deployments subject to an interference constraint and under specific quality of service (QoS) guarantees. The interference constraint corresponds to the upper limit of the received power that can be tolerated at the licensed users’ due to transmissions from unlicensed users. The QoS guarantees stem from the requirements imposed by the applications running at the users’ terminals. A cross-layer design is adopted that maps the user’s requirements into delay related QoS guarantees at the data link layer and error probability QoS guarantees at the physical layer. The obtained numerical results provide important insights regarding the impact of the considered constraint and guarantees on the achievable spectral efficiency of cognitive radio networks.     

End-to-end support for statistical quality of service in heterogeneous mobile ad hoc networks

In heterogeneous mobile ad hoc networks (MANETs), different types of mobile devices with diverse capabilities may coexist in the same network. The heterogeneity of MANETs makes end-to-end support for quality of service (QoS) guarantees more difficult than in other types of networks, not to mention the limited bandwidth and frequent topology changes of these networks. Since QoS routing is the first step toward achieving end-to-end QoS guarantees in heterogeneous MANETs, we propose a QoS routing protocol for heterogeneous MANETs. The proposed protocol, called virtual grid architecture protocol (VGAP), uses a cross-layer approach in order to provide end-to-end statistical QoS guarantees. VGAP operates on a fixed virtual rectilinear architecture (virtual grid), which is obtained using location information obtained from global positioning system (GPS). The virtual grid consists of a few, but possibly more powerful, mobile nodes known as ClusterHeads (CHs) that are elected periodically. CHs discover multiple QoS routes on the virtual grid using an extended version of the open shortest path first (OSPF) routing protocol and an extended version of WFQ scheduling policy that takes into account the wireless channel state. Moreover, VGAP utilizes a simple power control algorithm at the physical layer that provides efficient energy savings in this heterogeneous setting. Simulation experiments show that VGAP has a good performance in terms of packet delivery ratio, end-to-end packet delay, call blocking probability, and network scalability.     

Evaluation of mobility and quality of service interaction

With the fast adoption of IP-based communications for mobile computing, users are expecting a similar service in wireless and wired networks. This raises the need for setting guarantees to the quality of the offered service (QoS), despite the technology of the access network (AN) or the mobility of the terminal. As mobile computing is getting more popular on a daily basis, new broadband cellular wireless ANs will appear with overlapping coverage in hot spots. This generates a new challenge for QoS provision, as it will have to deal with fast mobility of terminals. Various QoS architectures have been defined, but none provides full support for guaranteed service levels for mobile hosts (MHs). This paper discusses the problems related to providing QoS to MHs and identifies the existing solutions and future work needed.     

区分服务网络中主动队列管理算法

现有区分服务网络的保证转发服务可提供稳定的带宽保证,但缺乏保证时延和分组丢失性能的有效方案.基于对RIO队列的稳态性能分析,提出两种自适应调整控制策略的主动队列管理算法(ARIO-D和ARIO-L).仿真结果表明,这两种算法在保持RIO算法带宽保证能力的同时,还可以提供稳定的和可区分的时延和分组丢失性能.采用ARIO-D和ARIO-L的保证转发服务可以为多媒体流量提供多种服务质量的定量保证.