Supporting end-to-end quality of service properties in OMG data distribution service publish/subscribe middleware over wide area networks

Assuring end-to-end quality-of-service (QoS) in distributed real-time and embedded (DRE) systems is hard due to the heterogeneity and scale of communication networks, transient behavior, and the lack of mechanisms that holistically schedule different resources end-to-end. This paper makes two contributions to research focusing on overcoming these problems in the context of wide area network (WAN)-based DRE applications that use the OMG Data Distribution Service (DDS) QoS-enabled publish/subscribe middleware. First, it provides an analytical approach to bound the delays incurred along the critical path in a typical DDS-based publish/subscribe stream, which helps ensure predictable end-to-end delays. Second, it presents the design and evaluation of a policy-driven framework called Velox. Velox combines multi-layer, standards-based technologies—including the OMG DDS and IP DiffServ—to support end-to-end QoS in heterogeneous networks and shield applications from the details of network QoS mechanisms by specifying per-flow QoS requirements. The results of empirical tests conducted using Velox show how combining DDS with DiffServ enhances the schedulability and predictability of DRE applications, improves data delivery over heterogeneous IP networks, and provides network-level differentiated performance.     

IP QoS体系结构

通过对目前正在研究的四类IP QoS协议（RSVP,DiffServ,MPLS,SBM）的详细分析比较发现：虽然它们都能够提供对QoS的支持,但都不能单独成为大规模网络环境下的QoS解决方案,只有对它们的综合应用才能真正实现广域环境下的数据流可预测性传输。以此为基础,给出了大规模网络系统中的IP QoS体系结构。     

IP网络设备中的QoS实现技术

随着IP网络的不断扩大和网络承载业务的不断增加,网络运营商在网络QoS方面的要求在不断提高,由最初的尽力而为和无需QoS保证的网络服务质量要求,逐渐演变到要求运营商提供严格端到端QoS的服务质量保证。本文主要是在基于MPLS的DiffServ网络中,在数据经过IP网络设备时,对QoS实现过程进行分析,并且对比分析了目前QoS在IP网络上实现的几种主要技术,着重对基于MPLS的DiffServ模型网络的DS域边界设备LER和域内设备LSR的QoS实现过程,包括用户识别、流分类、队列调度和拥塞控制等做了全面的论述。     

IPv6环境下的端到端QoS模型

IP网络将向着IPv6的方向发展,提供可靠的网络服务并保证服务质量是未来IPv6网络需要解决的关键问题.介绍了IPv6的QoS功能,在分析比较综合服务(integrated services,IntServ)、区分服务(differentiated services,DiffServ)和多协议标签交换(multiprotocol label switching,MPLS)等服务质量模型的基础上,提出了一个基于IPv6的端到端QoS模型,探讨了模型的功能组成和工作过程,指出了进一步研究的方向.     

DiffServ和MPLS相结合的流量工程机制

MPLSTE对传统的流量工程进行扩展,实现端到端的QoS保证,但是以流量中继为服务粒度。对流量缺乏区分服务的能力。DifIServ模型提供了区分服务,但是缺乏端到端的QoS有效路由策略。通过将MPLSTE的有效路由策略和DiffServ的区分服务相结合,引入区分服务感知的流量工程．运用带宽约束模型,在网络中实现端到端区分服务的QoS保证。     

IP QoS技术探讨及应用部署

本文以河北财政综合业务网改造过程中的IP QoS部署为例.对IP QoS技术发展的历史,标准和实际应用情况进行了回顾.选择差分服务作为综合业务网IPQoS部署模型.在全网路由器上部署统一策略的CBQ队列实现对不同业务应用的相应服务质量保证.从实际工作出发对TCP/UDP与IP QoS的关系.QoS在工作中的误区.IP QoS的测试方法以及需要注意的问题做出了较为深入的探讨.     

IP媒体流业务在3G移动网络中的应用

主要从理论上研究了3G网络中使用的一种流媒体的端到端QOS框架，探讨了运用PLMN中的多媒体流业务避免通过外部的IP-PDN访问流业务的可能性。在这个框架的基础上分析了流会话的UMTS和IETF下的协议之间的相互作用。这两组协议可以合作提供无缝的端到端的实时业务。特别是，本文提出P多媒体子系统可以利用实时流协议，将其控制范围从基于SP的业务延伸到基于R御的业务，如多媒体流媒体业务。在提出上述框架的基础上，本文还概括了3C移动网络中的音频流业务的提供。     

Interworking of heterogeneous access networks and QoS provisioning via IP multimedia core networks

Moving towards packet networks, where IP will have a prominent role, constitutes nowadays a widely accepted perception of future communications, the first instance of which has begun to materialise with the IP multimedia core network subsystem (IMS). By specification, IMS is the first implementation towards reaching converged communications which allows users to communicate with video, audio and multimedia content, via any fixed, mobile and wireless access network type, with controllable QoS. To enable IMS communications across heterogeneous networks, incorporating UMTS, WLAN and fixed IP access points, 3GPP and ETSI’s TISPAN currently work on schemes for controlling bandwidth allocation at the service level by employing logical interfaces that carry SIP messages. This article analyzes how interconnection between such heterogeneous networks may be performed on real platforms. In this effort, special attention is paid to the way the various interconnection possibilities can affect end-to-end QoS provisioning.     

Fast setup of end-to-end paths for bandwidth constrained applications in an IP/MPLS–ATM integrated environment

Transport networks are currently being moved towards a model of high performance Internet Protocol/Multiprotocol Label Switching (IP/MPLS) routers interconnected through intelligent core networks. Currently, Asynchronous Transfer Mode (ATM) technology has been widely deployed in several network backbones along with the Private Network-to-Network Interface (PNNI) protocols as the control plane. In order to cope with the increasing Internet traffic demands in the current context, fast setup of end-to-end paths with the required Quality of Service (QoS) is necessary.This paper analyzes the case of two IP/MPLS networks interconnected through an ATM core network, assuming MPLS as the mechanism to provide Traffic Engineering in the IP networks, and a PNNI-based control plane in the core network. This paper aims to define a mechanism needed to set up a fast end-to-end QoS Label Switched Path (LSP) between two Label Switched Routers (LSRs) belonging to different IP/MPLS domains. First, the fast end-to-end setup is achieved by modifying the network backbone control plane. Second, two different aggregation schemes are proposed to summarize the QoS network state information to be transported through the ATM core network. Therefore, both the efficient aggregation schemes and the fast mechanism allow source routing to set up a path faster than the existing methods and to reduce the blocking probability using a summary of the available resource information.     

A Novel Framework for IP DiffServ over Optical Burst Switching Networks

This paper presents a novel framework for IP Differentiated Services (DiffServ) over optical bursts witching (OBS), namely, DS-OBS. The network architecture, functional model of edge nodes and core nodes,the control packet format, a novel burst assembly scheme at ingress nodes and scheduling algorithm of core nodes are presented. The basic idea is to apply DiffServ capable burst assembly at ingress nodes and perform different per hop behavior (PHB) electronic treatments for control packets of different QoS class services at core nodes. Simulation results show that the proposed schemes can provide the best differentiated service for expedited forwarding (EF), assured forwarding (AF) and best effort (BE) services in terms of end-to-end delay, throughput and IP packet loss probability.     

基于IMS的E2E QOS控制机制

3GPP提出的IMS用于提供各种实时多媒体业务,未来的实时多媒体服务将以视频、音频以及视频、音频的混合为主,对于实时性和延迟的要求很高,需要E2E的QOS的支持。文章分析了现有的IMS的QOS机制的实现以及存在的不足,提出了一种新的基于策略的E2EQOS机制。新的机制主要实现了IMS中的各个层次间的相互协作、SIP协议的扩展和PDF功能的改进,实现了对多媒体业务实时性的提高并且缩短了延迟。     

支持QoS的SIP代理服务器方案的设计与实现

从如何提高基于SIP协议的VoIP系统的语音质量出发，分析了该系统与MPLS技术结合处的难点，并提出了一种支持QoS的SIP代理服务器模型的解决方案。该方案的设计结构清晰、可扩展性强，解决了SIP代理服务器在IP网络中没有会话服务质量控制能力的问题，是一种好的融合VoIP及MPLS两大技术的应用模型。该方案目前已运用于基于嵌入式Linux平台的VoIP系统中，完全能够满足高质量语音的需求。     

比例区分服务模型下的绝对时延保证

区分服务是在IP网络中实现QoS(Quality of Service)保证的一种体系结构，它在保持网络可扩展性的同时，为用户业务提供了有差别的服务，而比例区分服务提供了更加精细的区分控制，讨论了当前利用比例区分保证业务QoS一些方法和思想，它们大多致力于单个网络节点资源的合理分配。基于用户更加关心其端到端上的QoS特性，提出在保障关键业务包时延特性的基础上，网络各中间结点协作保证完成用户端到端上的包时延要求，在整个网络上合理分配资源。仿真结果表明，在相同的网络负载下，网络满足用户端到端上的包时延要求的能力大为提高。     

IP over Ethernet via fiber

IP over Ethernet via fiber will provide the ability to deliver the converged services of video, voice and data. It will enable a seamless transition of services between local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), and first-mile access networks. Today LANs are the equivalent of giant bandwidth silos, but when communication needs to extend beyond the LAN boundary, transmission is often reduced to T1 level speeds or worse. This bottleneck will dissipate, and the distinction between WANs and MANs will become more blurred, as Ethernet becomes prevalent in these two markets. The paper considers access, capacity, IP telephony, multimedia and extranets     

Model driven middleware: A new paradigm for developing distributed real-time and embedded systems

Distributed real-time and embedded (DRE) systems have become critical in domains such as avionics (e.g., flight mission computers), telecommunications (e.g., wireless phone services), tele-medicine (e.g., robotic surgery), and defense applications (e.g., total ship computing environments). These types of system are increasingly interconnected via wireless and wireline networks to form systems of systems. A challenging requirement for these DRE systems involves supporting a diverse set of quality of service (QoS) properties, such as predictable latency/jitter, throughput guarantees, scalability, 24x7 availability, dependability, and security that must be satisfied simultaneously in real-time. Although increasing portions of DRE systems are based on QoS-enabled commercial-off-the-shelf (COTS) hardware and software components, the complexity of managing long lifecycles (often ∼15-30 years) remains a key challenge for DRE developers and system integrators. For example, substantial time and effort is spent retrofitting DRE applications when the underlying COTS technology infrastructure changes.This paper provides two contributions that help improve the development, validation, and integration of DRE systems throughout their lifecycles. First, we illustrate the challenges in creating and deploying QoS-enabled component middleware-based DRE applications and describe our approach to resolving these challenges based on a new software paradigm called Model Driven Middleware (MDM), which combines model-based software development techniques with QoS-enabled component middleware to address key challenges faced by developers of DRE systems — particularly composition, integration, and assured QoS for end-to-end operations. Second, we describe the structure and functionality of CoSMIC (Component Synthesis using Model Integrated Computing), which is an MDM toolsuite that addresses key DRE application and middleware lifecycle challenges, including partitioning the components to use distributed resources effectively, validating software configurations, assuring multiple simultaneous QoS properties in real-time, and safeguarding against rapidly changing technology.     

Assured end-to-end QoS through adaptive marking in multi-domain differentiated services networks

The issue of resource management in multi-domain Differentiated Services (DiffServ) networks has attracted a lot of attention from researchers who have proposed various provisioning, adaptive marking and admission control schemes. In this paper, we propose a Reinforcement Learning-based Adaptive Marking (RLAM) approach for providing assured end-to-end quality of service (QoS) in the form of end-to-end delay and throughput assurances, while minimizing packet transmission cost since ‘expensive’ Per Hop Behaviors like Expedited Forwarding (EF) are used only when necessary. The proposed scheme tries to satisfy per flow end-to-end QoS through control action,s which act on flow aggregates in the core of the network. Using an ns2 simulation of a multi-domain DiffServ network with multimedia traffic, the RLAM scheme is shown to be effective in significantly lowering packet transmission costs without sacrificing end-to-end QoS, when compared to the commonly used static marking scheme.     

Quality-of-service mapping mechanism for packet video indifferentiated services network

This paper presents a futuristic framework for quality-of-service (QoS) mapping between practically categorized packet video and relative differentiated service (DiffServ or DS) network employing unified priority index and adaptive packet forwarding mechanism under a given pricing model (e.g., DiffServ level differentiated price/packet). Video categorization is based on the relative priority index (RPI), which represents the relative preference per each packet in terms of loss and delay. We propose an adaptive packet forwarding mechanism for a DiffServ network to provide persistent service differentiation. Effective QoS mapping is then performed by mapping video packets onto different DiffServ levels based on RPI. To verify the efficiency of proposed strategy, the end-to-end performance is evaluated through an error resilient packet video transmission using ITU-T H.263+ codec over a simulated DiffServ network. Results show that the proposed QoS mapping mechanism can exploit the relative DiffServ advantage and result in the persistent service differentiation among DiffServ levels and the enhanced end-to-end video quality with the same pricing constraint     

An Effective Feedback Control Mechanism for DiffServ Architecture

As a scalable QoS(Quality of Service)architcture,DiffServ(Differentiated Service)mainly consists of two components:taffic conditioning at the edge of the DiffServ domain and simple packet forwarding inside the DiffServ domain.DiffServ has many advantages such as flexbility,scalability and simplicity.But when providing, AF (Assured Forwarding) services ,DiffServ has some problems such as unfairness among aggregated flows or among micro-flows belonging to an aggregated flow.In this paper,a feedback mechanism for AF aggregated flows is proposed to solve this problem.Simulation results show that this mechanism does improve the performance of DiffServ.Firt,it can improve the fairness among aggregated flows and make DiffServ more friendly toward TCP (Transmision Control Protocol)flows.Second,it can decrease the buffer requirements at the congested router and thus obtain lower delay and packet loss rate.Third,it also keeps almost the same link utility as in normal DiffServ,Einally,it is simple and easy to be implemented.     

Network convergence and QoS for future multimedia services in the VISION project

The emerging use of real-time 3D-based multimedia applications imposes strict quality of service (QoS) requirements on both access and core networks. These requirements and their impact to provide end-to-end 3D videoconferencing services have been studied within the Spanish-funded VISION project, where different scenarios were implemented showing an agile stereoscopic video call that might be offered to the general public in the near future. In view of the requirements, we designed an integrated access and core converged network architecture which provides the requested QoS to end-to-end IP sessions. Novel functional blocks are proposed to control core optical networks, the functionality of the standard ones is redefined, and the signaling improved to better meet the requirements of future multimedia services. An experimental test-bed to assess the feasibility of the solution was also deployed. In such test-bed, set-up and release of end-to-end sessions meeting specific QoS requirements are shown and the impact of QoS degradation in terms of the user perceived quality degradation is quantified. In addition, scalability results show that the proposed signaling architecture is able to cope with large number of requests introducing almost negligible delay.