Managing Quality-of-Service in Internet Applications Using Differentiated Services

Advances in networks during the past decades have fostered the deployment of a variety of Internet applications. Many of these applications have a range of Quality-of-Service (QoS) requirements, some involving network throughput, delay, and reliability. Consequently, there is growing need for network services that can differentiate applications having QoS requirements from those without and to be able to further classify applications with QoS requirements into different classes at the IP-network level. The Internet Engineering Task Force (IETF) has proposed Differentiated Services (DiffServ) to provide QoS in IP-based networks. The goal of DiffServ is to define configurable types of packet forwarding that can provide service differentiation for large aggregates of network traffic. We report on our investigation of Relative Proportional Differentiated Services to implement DiffServ in IP-based networks and one that supports the provisioning and management of QoS for Internet Applications. The main contributions of the paper are the introduction of a novel traffic conditioning architecture for the marker and shaper/policer which relies on feedback from a metering component, and the provision for a QoS manager to enable a network administrator or a management application to dynamically adjust control parameters.     

无线Mesh网络中VOIP的QoS性能分析

针对VoIP(Voice over IP)业务在无线Mesh网上进行传输时存在服务质量(QoS)需求难以保证、带宽利用率低的问题,介绍了VoIP的QoS影响因素,分析了端到端时延、时延抖动和丢包率等几个重要参数,并对VoIP在无线Mesh网中的传输性能进行了论述。提出了基于无线Mesh网络的QoS保证机制,可以为端到端的数据传输公平的分配带宽,并能在保证QoS下实现大规模的实时任务的多跳转发。仿真试验表明能有效降低端到端时延,有着更好的QoS性能。     

Quality-of-service routing in IP networks

Multimedia applications such as video-conferencing, telemedicine, HDTV, etc. have very stringent quality-of-service (QoS) demands and require a connection-oriented service. For these applications, a path satisfying their requirements in terms of bandwidth, delay buffer, etc. needs to be found. As conventional IP routing is based only on hop counts, it is not suitable for multimedia applications. It is clear that, to route requests that have QoS requirements, existing routers should be made QoS aware and the packet forwarding should be based on QoS parameters. Also, routing protocols like OSPF and RIP must be extended suitably to facilitate QoS routing. The goal of QoS routing algorithms is to find a loop-less path satisfying a given set of constraints on parameters like bandwidth, delay, etc. The path selection process could return either the entire path to the destination or the best next hop for the request. The first case is called “source routing” and the second is referred to as “distributed routing”. In this paper, we propose a new distributed QoS routing algorithm for unicast flows, which has a very low call establishment overhead. Our algorithm makes use of existing IP routing protocols such as OSPF and RIP with minimal modifications     

Quality of service provisioning for distributed data center inter-connectivity enabled by network virtualization

Today’s service platform or Cloud service models, such as Infrastructure-as-a-Service (IaaS), enable customers to deploy and execute applications on an on-demand available infrastructure. Such platforms reduce operational expenses for the service provider and lower the entry barrier for small and medium enterprises. However, current commercial solutions do not provide sufficient quality of service (QoS) guarantees for some applications. For example, they do not support various interactive real-time applications.In this paper, we introduce a way overcome these current Cloud service limitations. We show how to provide and guarantee quality of service requirements for resource networks within an IaaS framework.Our work has focused on methods for network resource management and flow control as well as QoS models. We have developed a framework that enables QoS support for real-time services executing within an IaaS environment.     

Differentiation, QoS guarantee, and optimization for real-time traffic over one-hop ad hoc networks

Nodes having a self-centrically broadcasting nature of communication form a wireless ad hoc network. Many issues are involved to provide quality of service (QoS) for ad hoc networks, including routing, medium access, resource reservation, mobility management, etc. Previous work mostly focuses on QoS routing with an assumption that the medium access control (MAC) layer can support QoS very well. However, contention-based MAC protocols are adopted in most ad hoc networks since there is no centralized control. QoS support in contention-based MAC layer is a very challenging issue. Carefully designed distributed medium access techniques must be used as foundations for most ad hoc networks. In this paper, we study and enhance distributed medium access techniques for real-time transmissions in the IEEE 802.11 single-hop ad hoc wireless networks. In the IEEE 802.11 MAC, error control adopts positive acknowledgement and retransmission to improve transmission reliability in the wireless medium (WM). However, for real-time multimedia traffic with sensitive delay requirements, retransmitted frames may be too late to be useful due to the fact that the delay of competing the WM is unpredictable. In this paper, we address several MAC issues and QoS issues for delay-sensitive real-time traffic. First, a priority scheme is proposed to differentiate the delay sensitive real-time traffic from the best-effort traffic. In the proposed priority scheme, retransmission is not used for the real-time traffic, and a smaller backoff window size is adopted. Second, we propose several schemes to guarantee QoS requirements. The first scheme is to guarantee frame-dropping probability for the real-time traffic. The second scheme is to guarantee throughput and delay. The last scheme is to guarantee throughput, delay, and frame-dropping probability simultaneously. Finally, we propose adaptive window backoff schemes to optimize throughput with and without QoS constraints.     

定向天线卫星网络空间重用的带宽预留算法

基于无线网络中设计提供服务质量(quality of service,QoS)的路由协议是一项具有挑战性的工作,提出无线卫星网络中基于定向天线的服务质量保证的空间重用的带宽预留算法。卫星网络中许多音/视频会议、远程教育等重要应用,需要服务质量保证。无线网络中的定向天线技术提供了显著增加空间重用性的能力,提高无线网络中的数据传输效率。研究使用定向天线的无线卫星网络中基于时分多址的带宽预留算法,该算法给不同方向的地面终端分配相同时隙来提高带宽资源的空间重用性,提高通信效率。通过模拟实验分析研究证明,该算法在服务质量调用成功率、吞吐量和延迟方面有比较好的性能。     

Quality of Service Networking for High Performance Grid Applications

This paper reports on different efforts to provide quality of service (QoS) Networking to Grid applications done in the context of the MB-NG, GRS and DataTAG EU projects. These are leading edge network research projects involving more that 50 researchers in the UK, Europe and North America, concerned with the development and testing of protocols and standards for the next generation of high speed networks. We have implemented and tested the Differentiated Services Architecture (DiffServ) in a multi-domain, 2.5 Gbits/s network (the first such deployment) defining appropriate Service Level Agreements (SLAs) to be used between administrative domains to guarantee end-to-end Quality of Service. We characterised several hardware implementations of DiffServ and concluded on their appropriateness for several network scenarios. Since current and future Grid applications will have to use modified mechanisms of congestion control we have evaluated old and new TCP implementations over a Differentiated Services Networks. These quality of service tests have also included innovative MPLS (Multi-Protocol Label Switching) experiments to establish guaranteed bandwidth connections to Grid applications in a fast and efficient way. We have also developed a software based bandwidth broker architecture for Grids based on IETF standards which allows applications to transparently request dynamic and advanced reservations and implemented it in a real experimental network. We finally report on experiences delivering Quality of Service networking to high performance applications like Particle Physics data transfer and High Performance Computation. This includes quantitative results on the performance improvements that QoS brought to real data transfers in the context of High Performance Computing.     

IP宽带网络QoS的定量分析研究

拥塞管理和拥塞避免机制实现网络IP服务质量(QoS)保证。该文以立足改善吞吐率、满足QoS需求和公平服务为特点出发,综合宽带IP的最新进展,对QOS涉及的参数进行定量分析,这对组建未来通信网将发挥重要的作用。     

QoS动态多播路由协议

保证服务质量的QoS（Quality of Service）路由是网络中解决OoS问题的一项关键技术．具有OoS约束的多播路由技术已成为网络领域的一个重要研究课题．该文研讨了具有QoS约束的动态多播路由问题．文中描述了一种适应于QoS多播路由的网络模型，提出了一种QoS动态多播路由协议（QDMRP）．QDMRP只要求网络链路（或节点）的局部状态信息，不需要维护全局状态信息．QDMRP较好地减少构造一棵多播树的开销．仿真实验结果表明：QDMRP具有较低的控制信息开销和节点加入时延，较好地适合于网络状态变化比较频繁的环境以及实时多媒体应用．     

基于混合遗传算法的多播路由多目标优化

互联网不断增长的多媒体应用引发人们研究如何满足这些应用的服务质量(QoS)约束.目前网络中多主机之间的多播通信一般需要严格的多个QoS保证,文中描述了一种适应于研究多播QoS路由多目标优化的网络模型,在此基础上提出了基于遗传算法和禁忌搜索混合策略的,具有多目标的多播路由QoS优化方法,以克服遗传算法的爬山能力差以及不成熟收敛等问题.此外还采用了改进的多播树编码方法及高效的遗传操作,同时还优化时延、丢包率和带宽利用率等不同的参数.实验结果表明,该算法为多播路由QoS多目标优化问题的求解提供了一种有效的新途径.     

Policy-based networks: hype and hope

As high availability requirements, new applications, and multimedia increase pressure on networks, IT is learning that adding bandwidth isn't enough to solve traffic related problems. Network administrators must also find ways to manage network resources effectively and efficiently. Emerging policy based networking (PBN) technologies help IT ensure that network users get the quality of service (QoS), security, and other capabilities they need. Policy based networks have the intelligence, in the form of business rules, needed to govern network operations. The networks use hardware and software technologies that let IT managers prioritize access to and consumption of network resources. PBN systems will also help make it easier to manage corporate networks as they become more distributed, attach a wider range of devices and applications, and host multiple data types with different latency and reliability requirements     

Spectrum sharing optimization with QoS guarantee in cognitive radio networks

In this paper, we propose an optimized spectrum sharing scheme based on the Hungarian Algorithm to guarantee the quality of service (QoS) for individual cognitive radio (CR) users belonging to different CR cells. The proposed scheme is most favorable for overlapping cells where the users are demanding channels for heterogeneous applications such as chatting, web browsing, or voice and video streaming. The spectrum sharing optimization with the QoS guarantee (SSO-QG) is an optimal scheme that can operate in throughput enhancement mode, high reliability mode and collision avoidance mode based on the weight assigned to the corresponding QoS parameters in accordance with the demands of different applications. Simulation results show that the proposed scheme outperforms the existing schemes in terms of forming the optimal sharing pattern and meeting the stringent QoS requirements fairly enough according to the demands of the cell. Moreover, it reduces collisions with primary users.     

ATM网络中的服务质量问题

文章基于ATM论坛及ITU的推荐协议,对ATM网络中关于服务质量(QoS)方面的一些概念如业务合同、业务参数、一致性校验、服务质量参数等做了解释说明,同时也涉及到了ATM网络服务质量的保证机制,最后简要介绍了服务质量问题的研究情况。     

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.     

User-perceived quality of service in wireless data networks

For so long, the term quality of service (QoS) has been a pursuit area for network engineers trying to dimension wireless networks to run in the most efficient way possible. Of late, there has been a trend reversal, looking at the user perceptions of the network performance to decide where dimensioning can have the greatest impact. This paper demonstrates the importance of defining the concept of user-perceived QoS and linking this to specific wireless data network parameters for some anticipated valuable applications. It has been shown that a quantitative rating can be obtained for a variety of important factors in the assessment of service quality, and mapped to specific values of multiple network parameters. We found QoS to be application-specific, where various applications require different levels of network performance to satisfy users. The role of physical location was also examined, investigating the influence of being indoors versus outdoors on the user perception of QoS.     

μRACER: A Reliable Adaptive Service-Driven Efficient Routing Protocol Suite for Sensor-Actuator Networks

We present reliable adaptive service-driven efficient routing (muRACER), a routing protocol suite based on a novel service-oriented design for sensor-actuator networks where nodes expose their capabilities to applications as a service profile. A node's service profile consists of a set of services (i.e., sensing and actuation capabilities) that it provides and the quality-of-service (QoS) parameters associated with those services (delay, accuracy, freshness, etc.). muRACER uses an efficient service-aware routing approach that aggressively reduces downstream traffic (from the sink to the network's nodes) by translating service profiles into efficient paths for queries. To support QoS, muRACER dynamically adapts each node's routing behavior and service profile according to the current context of that node, i.e., number of pending queries and number and type of messages to be routed. Finally, muRACER improves end-to-end reliability through a scalable reputation-based approach in which each node is able to locally estimate the next hop of the most reliable path to the sink. Service- and context-aware reliable routing enhances the network's efficiency and effectiveness (satisfaction of applications' QoS requirements). We implemented muRACER on top of TinyOS and conducted several experiments that confirmed muRACER's ability with regard to each of its design objectives.     

Bandwidth Aggregation-Aware Dynamic QoS Negotiation for Real-Time Video Streaming in Next-Generation Wireless Networks

In next generation wireless networks, Internet service providers (ISPs) are expected to offer services through several wireless technologies (e.g., WLAN, 3G, WiFi, and WiMAX). Thus, mobile computers equipped with multiple interfaces will be able to maintain simultaneous connections with different networks and increase their data communication rates by aggregating the bandwidth available at these networks. To guarantee quality-of-service (QoS) for these applications, this paper proposes a dynamic QoS negotiation scheme that allows users to dynamically negotiate the service levels required for their traffic and to reach them through one or more wireless interfaces. Such bandwidth aggregation (BAG) scheme implies transmission of data belonging to a single application via multiple paths with different characteristics, which may result in an out-of-order delivery of data packets to the receiver and introduce additional delays for packets reordering. The proposed QoS negotiation system aims to ensure the continuity of QoS perceived by mobile users while they are on the move between different access points, and also, a fair use of the network resources. The performance of the proposed dynamic QoS negotiation system is investigated and compared against other schemes. The obtained results demonstrate the outstanding performance of the proposed scheme as it enhances the scalability of the system and minimizes the reordering delay and the associated packet loss rate.     

基于不确定参数的QoS路由研究

作为未来网络资源管理的一个重要组件，QoS路由问题越来越受到人们的重视。为了保证网络服务质量，希望根据多个QoS约束的尺度（metrics)来选择可行的路由。但由于网络本身的动态性和复杂性，网络状态信息具有固有的不确定性，因此有必要研究不确定参数对QoS路由的影响。通过形式化地描述基于带宽和延迟的不确定参数的QoS路由问题，给出了相应的处理模型和算法，并从实现的角度探讨了具有一定适应性的多路径QoS路由机制。     

基于跨层的中高速传感器网络多元参数调度与资源自适应分配算法

针对中高速传感器网络中不同业务对QoS(quality of scrvice)的不同要求,跨层考虑物理层和数据链路层参数,提出了一种适合混合业务的多元参数调度算法和资源分配算法。该算法根据不同的业务动态调整时延补偿因子和吞吐量补偿因子两个参数,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模型,对于实时业务能满足时延较小的要求,对于非实时业务能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系统功率效率和用户服务质量满意度之间取得折衷,并保证不同类型业务用户间的公平性。