用于MPLS流量工程的最小延时和最小干扰路由算法

借鉴最小干扰路由算法(MIRA)的思想,提出一种最小延时和最小干扰路由算法MDMI,以实现用于多协议标签交换(MPLS)流量工程的服务质量(QoS)路由方案。该算法首先选择k条最小时延备选路由,然后通过网络流计算避开关键链路选路。该算法在实现负载均衡、提高网络资源利用效率的同时提供了一种延时控制方式。仿真结果表明,该算法以k倍时间复杂度提升为代价,在满足标签转发路径(LSP)请求和资源利用率方面能达到较好的性能。     

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     

MPLS流量工程最小冲突路径算法

优化网络资源利用是Internet流量工程的重要目标之一.最小冲突路由机制通过利用多协议标记交换(MPLS)网络中的源-目的(SD)节点对信息,在为业务流请求选择标记交换路径(LSP)时,尽可能避免当前请求与将来请求之间的冲突,实现网络资源的合理利用.作者基于最小冲突机制,提出一种新颖的最小冲突路径算法(LIP).LIP通过简单的最短路径算法定位关键链路,并将链路剩余容量、节点对之间的冲突和竞争结合起来定义链路权重,在实现网络资源高效利用的同时,降低了算法的计算复杂度.实验结果进一步验证,相对于以往算法,LIP在请求带宽拒绝率、网络带宽接收量和LSP平均路径长度等方面都比较理想.     

MPLS的基于最小干涉的负载均衡算法研究

当MPLS网络中的业务流请求存在时间上的先后顺序时,选择一个高效的路由算法使得已存在的业务流的LSP对后续业务流的LSP路由影响最小变得很重要.在分析了常用的几种QoS保障的算法基础上,提出了一种基于最小干涉的负载均衡算法.该算法解决了MPLS网络中所有"入口/出口对"之间的业务流相互干扰的问题,为后续业务流路由预留了必要的"关键链路".     

MPLS流量工程中的约束路由算法

该文提出一种基于MPLS流量工程的约束路由算法—BHRA。该算法以带宽为主要约束条件,兼顾跳数约束来确定链路权重,并利用最短路径算法(SPF)来寻找权重和最小的路径。仿真实验表明与CSPFHopCount算法及MIRA算法相比该算法在网络负载均衡,限制最大链路利用率,以及LSP的请求拒绝率方面表现出更好的性能。     

MPLS流量工程及其形式化研究

MPLS被认为是下一代IP骨干网络技术，而流量工程是合理使用网络资源保障QoS的关键．支持MPLS的路由器可以使用新的机制实现流量工程，通过在线或离线的算法计算LSP确保QoS．在综述了MPLS应用于流量工程的优势、QoS路由、接纳控制、重新路由、容量设计和部署等问题及其形式化研究等方面的最新工作的基础上，对几种MPLS QoS路由的算法进行了对比和总结，并分析了进一步的研究方向和问题．     

基于NS2的MPLS流量工程仿真研究

MPLS被认为是下-代Internet骨干网络的核心技术,利用MPLS可以有效实施流量工程.文中对MPLS技术进行了介绍,针对流量工程的要求,给出了满足MPLS流量工程要求的系统模型.通过对仿真工具NS2的扩展,建立了一个MPLS流量工程仿真器,可以实现对MPLS转发技术和约束路由算法进行性能评估.仿真器的核心思想是,在标记交换路由器LSR模型中实现了标记分发、信令协议和路由协议扩展等基本功能;在标记边缘路由器LER模型上实现了对显示路由算法的支持.     

MPLS路由机制及其仿真研究

利用多协议标记交换MPLS(Multi-Protocol Label Switch)实施流量工程是一种具有巨大技术优势的新型技术.首先对支持流量工程的路由算法进行了分析和比较,然后对网络仿真器NS2(Network Simulator,version 2)进行扩展,实现MPLS仿真器模型.在此基础上针对不同网络拓扑和路由机制进行仿真实验,根据仿真实验的结果,对MPLS网络性能进行评估.     

MPLS流量工程提升IP网络QoS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,并通过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。该文在总结现有IPQoS主要技术的基础上,进一步论述了MPLS流量工程的主要体系结构和实现机制。并通过实验对比分析了MPLS流量工程相对于传统IGP在优化网络资源和支持显式路由LSP的优势并测试了对IP网络QoS的提升。     

MPLS网络中LSP模型改进研究

在MPLS网络标签交换路径(LSP)模型中,通常采用第二层直通式(L2-CTS)或第三层缺省路由交换技术.传统的L2-CTS是基于源节点到目的节点传输(P2P)的,没有考虑到建立的LSP是否是最佳.文中提出了一种改进的L2-CTS技术,根据标记交换路由器(LSR)和标记边界路由器(LER)建立的网络拓扑信息,LSR利用Dijkstra算法来计算最短的LSP,从而提高了网络传输效率.理论分析及仿真结果表明,在MPLS网络中,该改进方法可以有效减小网络传输时延,并提高传输流分发到不同标记交换路径的效率,提高了网络的服务质量.     

一种新的MPLS流量工程路由算法MSMR

本文提出了一种新的用于多协议标签交换网络流量工程的动态路由算法。先前研究者们提出的MIRA等著名算法试图通过绕开关键链路而最小化不同源-目的节点对之间的干涉。但是,有些情况下,这些算法可能选择过长的路径,或在寻找关键路径时判断不准确。因而本文提出了一种新的最大化其它入出口对之间的最大流之和的启发式算法。模拟结果证明了算法在拒绝率和吞吐量方面达到了更好的性能。     

Extension of Multiprotocol Label Switching for long-range dependent traffic: QoS routing and performance in IP networks

This paper presents an extension to the Multiprotocol Label Switching (MPLS) traffic engineering in IP networks with long-range dependent traffic. The extension provides the ability to diverge traffic flows away from the shortest path calculated by the traditional IP routing protocols into a less congested area of the network. When the traffic burstiness of a packet flow exceeds a predefined threshold, the extension calculates the cost of the traffic distribution and the effectiveness of Label Switching Routers (LSPs) to minimize the number of discarded packets. The simulation results demonstrate that the extension significantly improves the overall network performance in link utilization, port processor utilization, message delay, number of dropped packets, and buffer usage level.     

基于MPLS网络的选播QoS路由算法

提出一种基于MPLS网络且保证QoS的选播路由算法。使用链路状态路由协议,找到一条从发出请求的客户到服务器方向上最小跳数的最优路径,该路径能满足选播服务带宽要求。使用度量为路径逆向(服务器到客户)上的链路带宽值,通过约束路由的标记分发协议,建立一条从服务器到客户方向的标记交换路径,并预留资源。仿真结果表明,在传输服务数据流时,该算法的时延及丢包率性能良好,能在一定程度上平衡服务器的负载。     

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.     

MPLS流量工程K路径标号算法

针对多协议标签交换流量工程(MPLS-TE)提出一种有带宽保证的K路径标号算法(KPLA),该算法利用扩展标号算法计算出K条最短路径,综合考虑了链路关键度和链路最大剩余带宽的影响,进一步结合预计算和在线计算减少计算复杂度.该算法目的是避免忽视重要的非关键链路和避免选择过长的路径,提供有效的QoS保证.仿真结果表明该算法路由拒绝率低,延迟小,吞吐量大,计算速度快,是一种高效快捷的动态路由算法.     

MPLS流量工程路由优化机制的研究

对最小干涉算法进行了链路权值优化研究,提出集中和分布相结合的方式计算显式路由的方法.使用专门的策略和权值服务器PAWS为链路计算权值,标记边缘路由器LER实施分布式最小干涉算法,计算满足带宽的显式路由.通过路由算法及其体系结构的优化,提高了MPLS显式路由计算的效率和准确性,增强了MPLS流量工程系统的可扩展性.     

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.