下一代网络QoS策略仿真

下一代网络(NGN)的一个重要特点是在基于IP数据包的基础上实现了话音、视频和数据业务的融合,要在统一的网络上为用户提供特性不同的各类业务,服务质量(QoS)成为一个突出的问题。下一代网络提出了实现机理各不相同的几种QoS策略模型,从而满足用户对服务质量的需求。本文在计算机网络仿真平台上,通过对各种QoS策略进行分析和网络仿真设计,得到了实施各种QoS策略情况下网络延迟、抖动等网络性能参数,通过对仿真结果进行分析和比较,为下一代网络业务融合并实施QoS策略提供科学的参考。     

一种基于反馈控制的业务质量保证方案

计算机与通信技术的发展,下一代网络(NGN)正成为人们研究的热点,下一代网络是以业务驱动(ServicesDriven)的网络,业务主要通过网络中的各种应用服务器来提供,业务种类将越来越多,同时业务的用户数量也会空前增加。随着业务种类的丰富,人们对业务质量的要求也会越来越高,而如何保证业务的质量是一个具有很大挑战性的问题。该文提出一种基于反馈控制的方法来保证应用服务器中的业务质量,这种方法通过对服务器的负载情况进行动态检测,将检测到的信息反馈给应用服务器的呼叫接纳控制(CAC)部件,通过控制接入的用户数量来保证业务的质量。这种方法很适合于应用服务器的动态特性,能够根据系统的负载情况自动调整接入的用户数量,减轻了手动配置系统的工作量。最后,还证明了该控制方法是稳定的。     

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。     

SLA-controlled interconnection charging in next generation networks

Next generation network (NGN) should facilitate a single party to establish quality of service (QoS) enabled path between the two IP providers mutually interconnected by one or more transit providers. For that purpose, an end-to-end service level agreement (SLA) should be negotiated and maintained. In this article, we propose interconnection charging, which is controlled by the end-to-end SLA. Relationships between the required, offered, and actually achieved inter-provider QoS are quantified through the degrees of offering and provisioning, at both end-to-end and per-domain levels. Nominal retail price offered to end users and interconnection costs related with particular SLA are then corrected if needed, depending on the offered and provisioned QoS levels. We further propose five policies for interconnection charging and compare them under different QoS provisioning scenarios. Results of the analysis indicate that a properly selected SLA-controlled interconnection charging policy should encourage providers: (1) to offer services with different QoS levels; (2) to offer service that perfectly or most approximately matches the required QoS and (3) to achieve the contracted QoS level.     

Leveraging deployment models on low-resource devices for cloud services in community networks

Community networks are crowd-sourced IP networks that evolved into regional-scale computing platforms. This has led to adapting the cloud computing model for services that can operate and use computing resources inside a community network. The network and computing infrastructure is contributed by individuals, companies, organizations and maintained by its members. Community cloud devices are often low-capacity computing devices, such as home gateways or cabinet servers, with limited capabilities. These devices are used to install and operate specific personal or community services, but can be turned into multi-purpose execution environments applying machine or operating system (container) virtualization. However that requires addressing the problems of resource sharing in low-capacity devices, related to predictable performance and isolation. Our comparative analysis with the current infrastructure in community networks gives evidence about how devices can concurrently run multiple services, the trade offs between the number and resource requirements of services and the degradation of quality that services may suffer.     

业务感知技术的下一代校园网QoS研究与仿真

基于软交换技术的下一代网络(NGN)具有分组化的、开放的、分层的网络体系结构,是未来网络的发展方向。本文通过研究当前软交换网络QoS的解决方案,提出了基于业务感知技术的贵州大学下一代校园网动态QoS模型。通过在OPNET中建立下一代校园网的网络模型,并对相关业务的QoS性能进行仿真,结果表明业务感知技术能为下一代校园网中的QoS提供一定的保障。     

SUTIL – Network selection based on utility function and integer linear programming

This work presents SUTIL, a mechanism for network selection in the context of next generation networks (NGN). SUTIL selection mechanism prioritizes networks with higher relevance to the application and lower energy consumption and it enables full and seamless connectivity to mobile user devices and applications. Consequently, SUTIL contributes to realize the vision of ubiquitous computing, in which services, devices, and sensor-enriched environments interact anytime, anywhere to accomplish human designed tasks. The provided solution is based on utility function and integer linear programming and it aims at: (i) maximizing the user satisfaction while meeting application QoS and (ii) minimizing the energy consumption of devices when connecting to a target network. The solution is global since it considers for a given base station all devices that are simultaneously candidate for handoff. Simulation results showed the benefits of SUTIL usage in NGN environments.     

Extending next generation network (NGN) architecture for connection-oriented transport

Next Generation Network (NGN) is the architecture of the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T in short) supporting the provisioning of Quality of Service (QoS)-guaranteed services over different packet transport technologies. Such capability derives from the effectiveness of a dynamic resource control performed by the Resource Admission Control Function (RACF) at service set-up.Control Plane (CP)-enabled connection-oriented transport networks can guarantee the QoS support for new bandwidth-greedy NGN services across the optical transport segment thanks to the ability of automatic path set-up and traffic segregation. But the Internet Engineering Task Force (IETF) standard for the CP in transport networks, i.e., the Generalized Multi-Protocol Label Switching (GMPLS) is not yet included within the NGN supported transport technologies.In this work, we outline architectural guidelines and design strategies for ITU-T RACF employment across GMPLS-controlled networks while providing a viable solution for dynamic resource control that takes into account operational issues for the integration of GMPLS capabilities within NGN architecture (i.e., supported interfaces, actual node capabilities).An NGN prototype implementing the proposed architectural enhancement is also presented as a proof of concept. The prototype highlights how the extended ITU-T NGN can set-up Multimedia over IP (MoIP) services using GMPLS-controlled transport objects.     

一种可支持多种多媒体业务的基于IMS的IPTV架构

IP多媒体子系统用于实现端到端的IP多媒体通信,具有接入无关性、对各种接入技术广适性的特点,因此,下一代网络采用IP多媒体子系统作为核心架构.提出一个基于IP多媒体子系统的IP电视架构,在IP多媒体子系统核心模块的基础上,以一组互相独立的基于会话初始化协议的功能模块构成应用服务器,并设计了能够支持和提供不同IM S业务的客户端与内容提供商端,使该IPTV框架可以在下一代网络上支持基于IP多媒体子系统的包括IPTV业务在内的多种多媒体业务.     

Dynamic resource control mechanism for multimedia overlay transport in NGN

This paper investigates a dynamic resource control mechanism to efficiently deliver NGN multimedia services while supporting quality of service (QoS) requirements and bandwidth flexibility in next generation networks (NGN). The proposed resource control aims to realize the dynamic and automatic setup and release of multimedia resource sessions across heterogeneous transport networks including IP, SONET/SDH, and WDM technologies. It can also provide not only low cost operations but also flexibility for multimedia resource control.     

IPv6隧道的NAT穿越技术及其在GPRS中的应用

随着NGN、3G等IP网络业务的开展,向IPv6过渡的需求越来越迫切。隧道技术是过渡初期最易采用的方式,由于网络中大量NAT设备的存在,隧道技术中的NAT穿越问题是不容忽视的重点。该文通过对现有的普通隧道技术和Teredo隧道技术分析后,从NAT设备后IPv6孤岛接入IPv6网络的角度,提出了实现IPv6网络互联的IPv4 UDP隧道实现方法,并详细说明在园区网和GPRS网络中的 应用。     

QoS-based evaluation of file systems and distributed system services for continuous media provisioning

This paper presents a QoS-based performance analysis of file systems and distributed object services for Continuous Media (CM) provisioning, as well as the details and implementation experiences of a continuous media file system and associated CM servers. For this we have implemented QoS-driven CM servers and the Presto continuous media file system (PFS) in the context of a distributed multimedia application development environment, and validate the performance of PFS against that of the conventional Unix file system through an experimental evaluation. Using our CM server prototype, we next examine the effect of continuous media data delivery on the three different kinds of network protocols such as CORBA, UDP/IP, and TCP/IP, with respect to QoS provisioning and throughput.     

End-to-End Resource Management for Federated Delivery of Multimedia Services

Recently, the Internet has become a popular platform for the delivery of multimedia content. Currently, multimedia services are either offered by Over-the-top (OTT) providers or by access ISPs over a managed IP network. As OTT providers offer their content across the best-effort Internet, they cannot offer any Quality of Service (QoS) guarantees to their users. On the other hand, users of managed multimedia services are limited to the relatively small selection of content offered by their own ISP. This article presents a framework that combines the advantages of both existing approaches, by dynamically setting up federations between the stakeholders involved in the content delivery process. Specifically, the framework provides an automated mechanism to set up end-to-end federations for QoS-aware delivery of multimedia content across the Internet. QoS contracts are automatically negotiated between the content provider, its customers, and the intermediary network domains. Additionally, a federated resource reservation algorithm is presented, which allows the framework to identify the optimal set of stakeholders and resources to include within a federation. Its goal is to minimize delivery costs for the content provider, while satisfying customer QoS requirements. Moreover, the presented framework allows intermediary storage sites to be included in these federations, supporting on-the-fly deployment of content caches along the delivery paths. The algorithm was thoroughly evaluated in order to validate our approach and assess the merits of including intermediary storage sites. The results clearly show the benefits of our method, with delivery cost reductions of up to 80 % in the evaluated scenario.     

基于MPLS的DiffServ模型研究

互联网的飞速发展引起越来越多的人对服务质量(QoS)的关注。基于传统IP网络的QoS保证已经很难有效达到高性能。多协议标签交换网络(MPLS)作为下一代网络(NGN)核心技术之一,在服务质量和流量工程方面具有重要作用。本文提出将MPLS网络的标签交换与区分服务模型相结合的QoS实现方法,并通过一系列实验数据对DiffServ overMPLS模型功能进行验证。     

视频点播服务器的服务质量控制框架

视频点播服务器工作于开放的网络环境中,系统负载难以预测,其运行时资源瓶颈依赖于实时服务类型.基于性能模型和实时负荷估计方法,本文提出视频点播服务器的服务质量控制框架,提供系统负荷监控、准入控制和区分服务等三种服务质量控制.实际系统的验证实验表明,本文的方法可以有效的对系统负荷进行监控,确保系统负荷稳定在服务提供商希望的水平线以下,向不同级别的用户提供不同质量级别的服务.     

Optimal Content Distribution in Video-on-Demand Tree Networks

Video-on-demand (VOD) services are expected to grow significantly over time, providing diverse programs for home entertainment, distance instruction, news on demand, and other applications. These services require large bandwidth resources. We present a model for a tree network where each node may have demands for multiple different VOD program families, where each program family is an aggregation of similar programs. The decision variables include location of VOD servers and assignment of program families to servers. The model considers cost of servers, cost of assigning program families to servers, and cost of link bandwidths used to broadcast programs. The objective is to minimize the sum of all these costs. The model is formulated as an integer program. We develop a dynamic programming formulation with multiple state variables and an algorithm that solves this model. Starting from the end nodes of the tree network, the algorithm determines optimal solutions to subtrees, eventually reaching the root node with the central server, thus providing an optimal solution to the entire network.     

IP网络中支持QoS的接纳控制算法

In the research of NGN,Network QoS control is one of currently research hotspots. Admission control is a significant method used to support QoS. This paper surveys the research of QoS-supported admission controlal gorithms in IP network. We categorize and compare some main admission control mechanisms in IP network,try to analyze the relationship among these mechanisms and ProPose our views on the future relevant research.     

A novel pricing approach to support QoS in 3G networks

Pricing in 3G and other communication networks may control and manage the utilisation of network resources. The available network resources get strained with increased usage levels, which results in poor service to the users. Most users prefer receiving high quality services at affordable costs. This requires the provision of QoS guarantees for network services at a low cost. In a real business scenario, this relationship is hard to achieve; moreover revenue sources for network operators have been shifting from the provision of network access to provisioning of rich services, e.g. multimedia services. To attain a functional compromise, we propose a pricing scheme that relies on service profiles to manage resource utilisation in a DiffServ-enabled 3G network. The service profiles define the QoS achieved for accessing services through a common resource pool, in which resource sharing is used to maximise network resource utilisation, user satisfaction and profits for the network operators. In an NGN scenario users would select pricing profiles according to their budgets, and the network will map these profiles to a set of QoS options that may translate to the choice of an access network for service access. In this paper, we present the mathematical model of the proposed pricing scheme, the proposed design of an evaluation framework, QoS performance results, and a service provisioning scenario illustrating the applicability of the proposed pricing scheme.     

Determining Server Locations in Server Migration Service to Minimize Monetary Penalty of Dynamic Server Migration

In this paper, we propose a new class of service called server migration service (SMS) to augment the existing IaaS (Infrastructure as a Service). SMS allows servers (server-side processes of a network application) to dynamically and automatically migrate as their clients (client-side processes of a network application) change their locations in order to reduce the total monetary penalty that the SMS provider pays to its SMS subscribers when failing to provide them with the guaranteed level of QoS. In this paper, we consider the monetary impact that arises from QoS degradation due to server migration and build an integer programming model to determine when and to which location servers should migrate to minimize the total monetary penalty incurred by the SMS provider. Numerical examples show that SMS achieves up to 96% lower total monetary penalty compared to that without server migration. Numerical examples also show that the integer programming model developed in this paper requires reasonable computation time under realistic parameter settings.     

改进的分布式编码转换服务器负荷分担方法

针对当大量移动客户端需要流媒体服务时,编码转换服务器之间的负荷分担方法会较大地影响到总的满足服务质量（QoS）的流的数目的问题,提出了一种新的基于编码转换服务器资源消耗加权的负荷分担方法,用于均衡分布式编码转换服务器间的负荷,能使分布式编码转换服务器的性能得到更多的扩展。实验中,通过增加编码转换服务器的数目,评估了该方法均衡负荷的优越性和可扩展性。