Deploying Diffserv at the network edge for tight SLAs, part I

In the first of a two-part series, we review industry best practices for designing, validating, deploying, and operating IP-based services at the network edge with tight service-level agreements (SLAs). We describe the important SLA metrics for IP service performance and discuss why Diffserv is the preferred technology to achieve these SLAs.     

基于QoS的IP VPN的研究

1 引言简单讲,虚拟专用网(Virtual Private Network)是利用公共网络基础设施(如Internet)来仿真专有广域网络,以下简称VPN。它正快速成为新一代网络服务的基础。目前VPN有多种类型,其中最主要的是基于IP的VPN与MPLS-VPN,这两种VPN各有优势。本文所关心的不是如何论证谁更合适,这超出本文的范围。我们所关心的是如何在IP-VPN体系结构上提供服务质量保证。     

基于策略的QoS管理模型及其关键技术研究

现有的策略管理框架PBNM不仅存在着策略决策点负担过重、容易形成单点瓶颈等缺陷，同时还缺乏与SLA管理的紧密结合和具体实现。在PBNM的基础上，以Diffserv环境为底层，提出了基于策略的分层分域的业务QoS管理模型PBQM，引入了域策略决策点DPDP，增加了SLA管理、QoS监测和基于知识发现的业务恢复等管理模块；并提出了基于策略的SLA到区分服务网络配置的映射算法，该算法能根据SLA自适应地选择网络设备的配置策略，同时也可以进行策略映射的优化。     

Diffserv与Intserv相结合的端到端QoS提供机制

目前IP网络的OoS研究促使了两种不同体系结构的出现：综合服务体系结构Intserv及其相应的信令协议RSVP和区分服务体系结构Diffserv。但这两种IP网络的QoS控制方案各有自己的长处和局限,都不能完全满足需要。为了支持端到端的QoS可考虑将Intserv/RSVP和Diffserv看作相互补充的技术,将其结合共同实现端到端的QoS提供机制,同时满足类似状态相关网络的强有力的服务及与状态无关网络近似的可扩展性和鲁棒性。对这两种体系结构的结合进行了具体的分析,并对存在的问题提出可能的解决办法。     

Internet区分服务及其几个热点问题的研究

综述了Ｉｎｔｅｒｎｅｔ在区分服务（Ｄｉｆｆｅｒｅｎｔｉａｔｅｄ ｓｅｒｖｉｃｅｓ,Ｄｉｆｆｓｅｒｖ）研究方面的一些最新的工作,分析了Ｄｉｆｆｓｅｒｖ的体系结构、Ｄｉｆｆｓｅｒｖ的典型服务与技术,并着重论述了Ｉｎｔｅｒｎｅｔ Ｄｉｆｆｓｅｒｖ所面临的问题,包括Ｄｉｆｆｓｅｒｖ与综合服务（Ｉｎｔｅｇｒａｔｅｄ ｓｅｒｖｉｃｅｓ,Ｉｎｔｓｅｒｖ）相结合的端到端服务质量（ＱｏＳ）提供机制、Ｄｉｆｆｓｅｒｖ     

支持QoS管理的下一代互联网IP业务的SLA违例处理及应用

为了实现对下一代互联网IP业务的SLA违例处理的规范化管理,保证业务正常、可靠、高质量地提供,定义了一个通用的SLA违例处理模板,详细描述了该模板的组成内容和属性,并在模板的基础上提出了能够保障服务质量的SLA违例处理的流程,最后讨论了与服务参数相关的SLA违例处理在服务保障阶段的应用实例。     

OpenIPTV: a comprehensive SDN-based IPTV service framework

IPTV is an emerging TV content delivery service that should guarantee Quality of Service (QoS) to deliver television contents over IP for their customers. However, providing such QoS regarding service level agreements (SLA) requires frequent service monitoring and adaptive configuration mechanisms. Nowadays, Software Defined Networks (SDNs) provide capabilities to deploy and manage networks dynamically and can maintain QoS. In this paper, a novel IPTV service framework (OpenIPTV) is proposed, which utilizes SDN as an underlying technology for providing QoS for IPTV customers in a shared backbone network. OpenIPTV is implemented in a well-known OpenDayLight controller and strictly followed a modular design for the sake of efficiency. OpenIPTV comprises all service requirements such as resource monitoring, channel changing, multicast group managing and dynamic QoS multicast traffic engineering. The performance of OpenIPTV is evaluated under different scenarios and experimental results confirmed the effectiveness of the proposed framework in terms of QoS metrics. Furthermore, experimental results show that OpenIPTV is a feasible and practical solution to deliver IPTV services with high level of QoS over SDN.     

面向SLA监测的IP网主动测试系统设计*

SLA是在现有IP网络基础上开展的新型服务模式。在SLA的实施过程中,对SLA的监测极为重要。鉴于网络主动测试所具有的优点,主动测试技术正成为一种重要的SLA监测技术。根据SLA监测的要求,借鉴已有主动测试系统结构模型,提出了一个面向SLA监测的IP网络主动测试系统结构设计,并对系统设计的关键问题作了分析。     

一种新型的IP网络QoS实现方式

目前的Internet只能提供"尽力而为"的服务,然而网络用户的不断增加,网络应用范围的不断扩大,各种实时性新型业务在传输的时候对网络提出了更高的要求。只有使IP网络中具备QoS保障机制才能够有效地解决IP新业务以及实时业务推广应用中碰到的问题。论文在对传统IP网络QoS实现方式进行研究分析的基础上,提出一种新的IP网络QoS实现方式,为IP网络提供较高水平的服务质量保障。     

基于Diffserv over Mpls的体系结构研究

讨论了IP QoS体系结构的发展,然后分别阐述了Diffserv模型和MPLS模型.为了提高IP QoS,给出了Diffserv over MPLS体系结构的实现,相比于其他的体系结构分析了Diffserv over MPLS的优势.     

公用IPv6网络承载服务SLA监测研究

分析了NGI中网络承载服务sIA(NSLA)的应用需求,针时NSLA可能的应用场合及IPv6特点定义了适用于NSLA的QoS参数:IP分组传送延迟(IPTD)、IP分组延迟变化(IPDV)、IP分组传送失败率(IPFR)和IP分组吞吐能力(IPTC),其中IPTC能有效刻画公用IP网段集维持业务流量模式的能力.分组识别和时钟同步是IPv6网络NSLA监测的两个关键问题.文中给出了分组识别的解决思路;为降低对同步的要求、支持较低成本的NSLA监测,除IFFD外其余参数均可容忍出入测量点之间存在有限的时钟不同步.此外,综合应用特点、用户感知、IPv6协议等因素,讨论了面向应用NSLA的QoS参数设定.最后设计了一个包括采集器、前端机、分析机、原始数据库和结果库等部件的NSLA监测系统,采用ON-OFF系统抽样方式被动监听自然流量,在各部件的协作下可实现各QoS参数的测量.     

基于MPLS的区分服务技术

传统的Internet只能提供尽力传送服务,但这种没有任何保证、不可预测的服务已不能满足许多应用的需要。IETF提出的Intserv/RSVP方案从技术角度可以提供灵活的服务质量,满足各种应用的需要,但该方案要求每个路由器保存每个连接的状态,复杂化了核心路由器的处理,因此实现 和配置是非常困难的。IETF提出的Diffserv将各种复杂的接入控制、每个连接的管理交给边界路由器处理,核心路由器只处理流量聚合,因而具有更好的伸缩性和鲁棒性。MPLS是一种可以在多种第二层媒质上进行标签交换的网络技术,将探讨如何结合Diffserv和MPLS两种技术,提供各种服务质量,特别是VPN。     

PROQOS—Dynamic SLA Management in DiffServ Space Links

Several base elements for the provision of quality of service guarantees have been developed in the recent past. Of these, the Differentiated Services (DiffServ) architecture stands out as the most promising. In spite of this, various issues remain, especially when multidomain DiffServ services are concerned. In this case, some forms of distributed management of Service Level Agreements that allow the specification, exchange, enforcement and monitoring of quality of service data must be in place. Although, again, some isolated solutions exist for each of these problems, considerable effort is necessary to make them work together. The project presented in this paper tried to assess the feasibility of providing differentiated quality of service in satellite IP networks, by developing a dynamic Service Level Agreement management solution for an IP over Digital Video Broadcast Satellite system. The functionality of the implemented system comprises system configuration, dynamic SLA negotiation, QoS monitoring and metering, SLA conformance checking, and QoS reporting to customers.     

Policy-based Diffserv on Internet servers: the AIX approach

The Internet infrastructure must evolve from best-effort service to meet the needs of different customers and applications. With Internet traffic differentiation, service providers can support a range of offerings, such as loss or delay bounds and network bandwidth allocation, to meet different performance requirements. The differentiated services (Diffserv) architecture provides a scalable approach, in which network access (or edge) devices aggregate traffic flows onto provisioned pipes that traverse a streamlined network core. We have identified the key requirements for provisioning Diffserv functions on Internet servers. Based on these requirements, we have implemented, and deployed, a policy-based architecture on IBM's AIX operating system that provides Diffserv services to both QoS-aware and -unaware applications     

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.     

在ATM网络上MPLS的实现

多协议标记交换技术(MPLS)能在主干网上大大提高IP转发性能，并提供服务分类(CoS)及服务质量保证(QoS)。MPLS在现有的主干ATM网上可提供高性能的IP服务。该文主要介绍了MPLS技术，并讨论了在ATM网上实现MPLS所必须解决的一些关健技术。     

QUIPS-II: a simulation tool for the design and performance evaluation of Diffserv-based networks

This article presents a discrete event simulator, called Queen's University IP Simulator-II, which can be used for the design and performance evaluation of Diffserv-based networks. The simulator implements both the expedited and the assured forwarding per-hop forwarding behaviors in Diffserv networks, sharing many features of the IETF proposals. By setting up a network model with variable parameters, simulation can be carried out to observe the Diffserv behavior. Some performance evaluations of both forwarding mechanisms are provided as examples.     

Service level agreements (SLAs) parameter negotiation between heterogeneous 4G wireless network operators

We are currently witnessing a growing interest of network operators to migrate their existing 2G/3G networks to 4G technologies such as long-term evolution (LTE) to enhance the user experience and service opportunities in terms of providing multi-megabit bandwidth, more efficient use of radio networks, latency reduction, and improved mobility. Along with this, there is a strong deployment of packet data networks such as those based on IEEE 802.11 and 802.16 standards. Mobile devices are having increased capabilities to access many of these wireless networks types at the same time. Reinforcing quality of service (QoS) in 4G wireless networks will be a major challenge because of varying bit rates, channel characteristics, bandwidth allocation and global roaming support among heterogeneous wireless networks. As a mobile user moves across access networks, to the issue of mapping resource reservations between different networks to maintain QoS behavior becomes crucial. To support global roaming and interoperability across heterogeneous wireless networks, it is important for wireless network operators to negotiate service level agreement (SLA) contracts relevant to the QoS requirements. Wireless IP traffic modeling (in terms of providing assured QoS) is still immature because the majority of the existing work is merely based on the characterization of wireless IP traffic without investigating the behavior of queueing systems for such traffic. To overcome such limitations, we investigate SLA parameter negotiation among heterogeneous wireless network operators by focusing on traffic engineering and QoS together for 4G wireless networks. We present a novel mechanism that achieves service continuity through SLA parameter negotiation by using a translation matrix, which maps QoS parameters between different access networks. The SLA matrix composition is modeled analytically based on the G/M/1 queueing system. We evaluate the model using two different scheduling schemes and we derive closed form expressions for different QoS parameters for performance metrics such as packet delay and packet loss rate. We also develop a discrete event simulator and conduct a series of simulation experiments in order to understand the QoS behavior of corresponding traffic classes.     

区分服务路由器软件结构研究

1.引言 Internet已经延伸到了世界的每一个角落,成为了各种应用的承载工具。在这些应用中,近年不断发展的多媒体应用如视频会议、视频点播(VOD)、VOIP等受到了广泛的关注,这些应用和普通的应用不同,它们对网络带宽、延迟、抖动、丢包率等有一定的要求,因此,网络必须对多媒体应用提供一定的服务质量(QoS)保证。当前的Internet采用的是best-effort(尽力服务)模型。在这个模型中,网络平等地处理所有数据包,尽它的最大努力转发数据包,其首要目标是实现对链路的统计复用以达到高网络利用率,路由器作为核心设备,它是无状态的,也就是说它     

一种基于区分服务网络的主动式队列管理算法

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，但缺乏对速率变化下平均队列长度和延迟时间的稳定性的保证，并且没有提供简化主动队列管理（AQM）算法参数设置的有效方案。基于对RIO、A-RED算法的分析研究，提出一种自适应调整控制策略的RIO算法（A-RIO）。仿真结果表明，该算法在保持了RIO算法优点的同时，还可以提供稳定的平均队列长度和延迟时间，同时可以简化参数的设置，从而有效地提高了区分服务网络中保证转发服务的性能。