IP网络QoS体系性能的研究

MPLS流量工程通过优化IP网络资源的使用以提高网络性能,同时结合约束路由和面向连接的标记交换路径提供了端到端的QoS保障。在网络上层,DiffServ和MPLS相结合,DiffServ将业务分类、整形、聚合,MPLS再将处理过的数据转换成不同的标签进行转发。在网络底层,MPLS与WDM光网络技术相结合,从而实现更快、更智能的数据传送。     

A novel path protection scheme for MPLS networks using multi-path routing

Multi-protocol label switching (MPLS) is an evolving network technology that is used to provide traffic engineering (TE) and high speed networking. Internet service providers, which support MPLS technology, are increasingly demanded to provide high quality of service (QoS) guarantees. One of the aspects of QoS is fault tolerance. It is defined as the property of a system to continue operating in the event of failure of some of its parts. Fault tolerance techniques are very useful to maintain the survivability of the network by recovering from failure within acceptable delay and minimum packet loss while efficiently utilizing network resources.In this paper, we propose a novel approach for fault tolerance in MPLS networks. Our approach uses a modified (k, n) threshold sharing scheme with multi-path routing. An IP packet entering MPLS network is partitioned into n MPLS packets, which are assigned to node/link disjoint LSPs across the MPLS network. Receiving MPLS packets from k out of n LSPs are sufficient to reconstruct the original IP packet. The approach introduces no packet loss and no recovery delay while requiring reasonable redundant bandwidth. In addition, it can easily handle single and multiple path failures.     

Call admission control and load balancing for voice over IP

IP networks are traditionally designed to support a best-effort service, with no guarantees on the reliable and timely delivery of packets. With the migration of real-time applications such as voice onto IP-based platforms, the existing IP network capabilities become inadequate to provide the quality-of-service (QoS) levels that the end-users are accustomed to. While new protocols such as DiffServ and MPLS allow some amount of traffic prioritization, guaranteed QoS requires call admission control. This paper reviews several possible implementations and shows simulation results for one promising method that makes efficient use of the network and is scalable to large networks.     

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。     

基于MPLS的IP-QoS机制研究

多协议标签交换（MPLS）网络层协议结合了异步交换模式（ATM）的交换技术和IP协议的路由技术,被认为是未来网络的关键协议,同时可被应用于IP网络提供服务质量保障IP-QoS和构建虚拟网.在介绍了综合服务模型IntServ和差分服务模型DiffServ两种服务模型工作原理和网络结构的基础上,重点对IP-QoS在MPLS域的实现机制及其实现的优势做研究了,最后对基于MPLS的IP-QoS应用做了分析.     

Path selection with preemption and re-routing control for multi-protocol label switching networks

Multi Protocol Label Switching (MPLS) networks enhance the services of conventional best-effort IP networks by providing end-to-end Quality of Service (QoS) guaranteed Label Switched Paths (LSP) between customer sites. The LSP has to be set up in advance before carrying the traffic. Contention for network resources may happen if many LSPs try to use a common network link with limited bandwidth. In this paper, we investigate the problem of providing services to high priority LSPs whereby existing LSPs with lower priority may be preempted. The consequent interruption of the services of preempted LSPs would detrimentally affect users’ perception on the QoS provided. Therefore, the preemption strategies may incorporate additional re-routing mechanisms to provide alternative paths for the LSPs which are to-be-preempted so that their services remain unaffected. A newly arrived high priority LSP in an MPLS network may find M possible paths between its source and destination. It may select the shortest path which may trigger preemption or choose a longer path which however utilizes more resources. We begin by formulating preemption strategies with global re-routing. Our investigations include the effects of routing of high priority LSPs on the shortest path and its alternative paths. We show that by persistently routing the high priority LSP on the shortest path, more preempted LSPs can be re-routed which would reduce the negative effects of preemption. However, as excessive re-routing may degrade the network performance as well, a re-routing control strategy is proposed to constrain the length of these re-routed paths. Finally, a decentralized preemption strategy with local re-routing is also presented to approximate the performance of the proposed strategy with significantly lower control overheads. Simulations show that with this approach, high priority LSPs can gain better access to network resources while simultaneously ensuring that, as compared to the existing preemption strategies, the network throughput and the ongoing connection services are not adversely affected.     

QoS-aware path switching for VoIP traffic using SCTP

Voice over Internet protocol (VoIP) has been a prevalent multimedia service nowadays. It allows us to transmit voice data over IP networks. However, quality of service (QoS) is a major challenge to VoIP services. It must provide similar quality to traditional public switched telephone network or cellular phone services. Therefore, QoS related protocols have become important for real-time applications. Multi-protocol label switch (MPLS) is one of the important techniques to improve the network performance from QoS point of view. It employs label swapping to speed up packet forwarding. However, when a large number of users utilize VoIP services, the network congestion issue still exists. It causes delay, jitter and packet loss that affect VoIP QoS. In this paper, we propose a QoS-aware path switching strategy by using stream control transmission protocol (SCTP) in MPLS network to improve the VoIP traffic. This was done by employing SCTP selective acknowledgment mechanism to report the transmission parameters of primary path and to determine the criteria to switch to backup path. Simulation results show significant improvement in VoIP QoS.     

基于MPLS实现IPv6网络QoS的新机制

通过分析IPv6的QoS特性以及DiffServ和MPLS技术，提出了在MPLS平台下通过TC字段实现IPv6网络QoS的新机制。该机制简化了网络结构设计，更容易提供端到端的QoS。试验结果表明，新机制可以充分利用网络资源，优化网络性能。     

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。     

IPv6 over MPLS网络中实现DiffServ的解决方案

如何在IPv6 over MPLS网络中提供端到端的服务质量？针对这个问题介绍了一个6PE-DiffServ解决方案（6PE,IPv6 Provider Edge Routers）。该方案使用6PE技术进行组网,通过统一的DiffServ策略的部署和BB-6PE（Bandwidth Broker for 6PE network）的集中管理,给由IPv4向IPv6过渡的网络提供DiffServ服务。6PE-DiffServ方案的可行性和有效性在CNGI-QoS实验网中得到了验证。     

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.     

Providing service differentiation in pure IP-based networks

The lack of an effective cooperation between the data, control and management plane of QoS routing solutions presented so far, prevents the implementation of service differentiation in the context of pure IP-based networks. Most of paths calculation proposals performed by the control plane are unaware of service characteristics of each flow. Scalable data plane QoS proposals ignore the issue about selecting the best paths to route the traffic. Proposed management plane schemes do not perform the network state maintenance and service level monitoring. Multi-service routing is a flow-based forwarding protocol that implements the service differentiation in pure IP-based networks, using a straight cooperation between data, control and management plane. This cooperation is accomplished by a data plane supporting the DiffServ model and performs route selection based on flows service class, which is exploited by the management plane to carry out the network state maintenance, and performance monitoring by using the RTCP protocol, to provide service metrics to control plane for route calculation. Simulation experiments show better performance results achieved by Multi-service routing compared to those obtained by traditional link state protocol with the DiffServ model and QoS routing in heavy loaded network scenarios of mixed traffic having different service requirements.     

基于MPLS的下一代网络QoS模型

介绍集成服务、区分服务、流量工程和MPLS几种常用的服务质量(QoS)技术,任何一种独立的技术都不能很好地解决QoS问题。该文提出一种将流量工程引入多协议标签交换(MPLS)网络并结合DiffServ和IntServ的QoS模型,阐述其原理及部分实现技术,利用NS2工具对提出的网络模型进行仿真。结果表明,与单纯的MPLS网络相比,该模型改善了网络延时,丢包率降低20%。     

一种分类预计算QoS路由算法

为了满足Internet上各种网络应用的传输服务质量的需求,Internet工程任务组(IETF)先后提出了集成服务/资源预留模型(integrated service/resource reservation protocol,简称IntServ/RSVP)、区分服务模型(differentiated service,简称DiffServ)以及从流量工程角度提出的多协议标记交换(multi protocol label switching,简称MPLS).这些服务模型都需要一个与之相适应的QoS路由机制     

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.     

支持区分服务的MPLS网络

多协议标记交换（MPLS：Multi-protocol Label Switching)技术为IP网络中实现服务质量（QoS),路由控制等提供了可行的解决方案。简单介绍了区分服务（Diff-Serv)和MPLS的基本技术框架,重在说明如何在MPLS网络中实现区分服务,通过两种标记交换通道分别对不同情况下的分组进行转发,利用MPLS头标中的标记和EXP域实现多等级的区分服务。     

A Bayesian decision theory approach for the techno-economic analysis of an all-optical router (extended version)

Typically, core networks are provided with both optical and electronic physical layers. However, the interaction between the two layers is at present limited, since most of the traditional transport functionalities, such as traffic engineering, switching and restoration, are carried in the IP/MPLS layer. In the light of this, the research community has paid little attention to the potential benefits of the interaction between layers, multilayer capabilities, on attempts to improve quality of service control.This paper shows when to move incoming label switched paths (LSPs) between layers based on a multilayer mechanism that trades off a QoS metric, such as end-to-end delay, and techno-economic aspects. Such a mechanism follows the Bayesian decision theory, and is tested with a set of representative case scenarios.     

一种基于MPLS保证每流服务质量的方法*

分析了当前网络中保证服务质量的机制,针对目前MPLS本身的服务质量只支持区分服务的现状,提出将动态分组状态模型用于MPLS的方法,通过将状态信息封装在MPLS分组的二层标签中,使核心网络在不需保存每流状态的情况下提供基于每流的服务质量。详细阐述了该方案的总体结构、数据平面和控制平面等,并通过在NS中模拟分析对该方案进行了验证。     

具有QoS保证的MPLS网络生存性策略*

概述了保证QoS的MPLS网络生存性中各种保护和恢复策略,包括它们对QoS的不同要求、算法思想、应用领域、各自的优缺点等.将MPLS网络生存性与DiffServ模型结合起来,针对不同的业务要求选出不同的保证QoS的生存性方法.