IP网络生存性研究综述

随着交互式应用和各种实时业务的增长对网络生存性要求的提高,IP网络的生存性研究受到了越来越多的关注。本文首先对IP网络生存性面临的问题以及影响因素作了概括,并且对目前有关纯IP网络生存性、MPLS网络生存性、IP网络与底层的生存性协调研究作了归纳总结,尤其对纯IP网络的生存性研究现状从多方面进行了比较详细的介绍,最后指出IP网络的快速重路由机制具有很好的实际应用潜力,保护恢复能力和服务质量在MPLS网络中的结合、动态多层保护则是未来IP骨干网生存性维护的发展方向。     

ATM网络中关键服务生存性保证机制

生存性是ＡＴＭ网络中亟待解决的问题,文中在介绍了当前ＡＴＭ网络中基于ＶＰ层的故障恢复机制后,引入生存重要性因子表征网络中不同服务的生存重要性,定义了加权恢复率;基于关键服务生存性保证的要求,提出了关键ＶＣ预建立保证连接和关键ＶＣ优先的实时恢复两种解决方式,并综合形成了关键服务生存性的保证机制。     

IP/MPLS over WDM网络生存性的研究

该文首先分析了IP/MPLS over WDM网络单层生存性和多层联合生存性,并就生存性策略的性能进行对比,然后对多层空闲资源分配进行了研究。     

网络生存性综述

当网络内出现故障时,网络维持服务连贯性的能力称之为生存性。在当前多层次的流量工程化IP网络中考虑生存性已经变得重要而且紧急。分析并比较了网络各层次中的生存性机制,包括WDM层、SDH层、1ATM层、MPLS层和IP层生存性机制的相关概念、分类和研究现状。最后介绍了在层间调和各种生存性机制的可行性与利弊。在进行流量工程设计的过程中适当地采用这些生存性机制,可以更好地实现流量工程目标。     

网络生存性评估模型的仿真分析

在准确评估网络性能的研究中,网络生存性是指在网络遭受攻击、故障或意外事故时,网络能够及时完成关键任务的能力.传统的评估方法,在面对随机攻击的情况下,设定的网络指标权重主观性较强,且难以适应时刻变化的网络环境造成评估不准.为了避免传统算法的缺陷,提出了一种卡尔曼滤波网络生存性评估方法.对网络资源进行区域划分,将网络分割为不同的子区域,分别对子区域进行计算,从而降低网络生存性评估计算的复杂度.利用卡尔曼滤波方法,建立网络生存性评估模型,从而完成网络生存性评估.实验结果表明,利用改进算法建立网络生存性评估模型,能够提高网络评估模型的适应性,从而有效提高了评估模型在不同网络环境下的评估能力.     

多协议标签交换网络中业务相关的故障自诊断与定位机制

为了克服多协议标签交换(MPLS)网络故障诊断与定位机制控制报文流量较大,不支持区分业务的生存性策略,不能自动触发的缺点,本文提出一种业务相关的故障自诊断与定位机制.该机制在业务源和目的节点之间建立一条与工作路径不相关的连接,与工作路径形成环路;当业务服务质量(QoS)性能下降时,自动触发业务相关的故障自诊断与定位机制,在环路上传输控制报文.仿真结果表明该机制不仅能够准确定位故障类型与发生位置,提供毫秒级故障自诊断与定位时间,还使用了较少的控制报文.     

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。     

基于漏洞扫描的生存性量化分析算法研究

针对信息系统生存性的概念和生存性评估的可抵抗性、可识别性、可恢复性、自适应性四个基本属性的定义,结合对成熟的网络安全技术--漏洞扫描技术的深入研究,提出了一种网络漏洞扫描和生存性分析攻击情景相结合的生存性分析方法,最终得出基于网络漏洞扫描技术的生存性量化分析是可行的结论.通过对漏洞库相关内容的总结,提出了基于漏洞扫描的生存性分析数据库应扩展的内容,最后,详细阐述了生存性量化分析中四个基本属性分量计算公式的算法研究过程,为信息系统的生存性分析系统的设计提供底层核心算法.     

基于MPLS的分级故障恢复机制

网络可靠性已经成为IP网的一个重要问题.目前关于IP网可靠性的讨论集中于MPLS的故障恢复机制.IETF提出了两种MPLS故障恢复模型保护交换和重路由,每种模型的恢复时间和资源开销是不同的.该文提出一种基于MPLS的分级故障恢复机制MBCR,它可以保证应用对可靠性和QoS的要求,同时使网络资源得到充分利用.     

华为基金资助项目基于约束马尔可夫决策过程的网络生存性研究*

给出了基于约束马尔可夫决策过程的网络生存性定义,提出了一个多层网络生存性研究框架和一种新的网络生存性设计方法。     

Design of Reliable IP/GMPLS Networks: An Integrated Approach

The increased bandwidth demand for new Internet applications suggests mapping IP directly over the wavelength-division multiplexing (WDM) layer. Since reliability is such a critical issue in these broadband networks, we propose an integrated design method which addresses the problem of survivability as viewed from the IP/MPLS layers but taking into account the failure mechanisms in the optical layer. This approach is becoming practical because of the emergence of generalized multiprotocol label switching (GMPLS) as a multilayer control plane that can support the signaling required for coordinating the restoration mechanisms in multiple layers.The model relies on network calculus to evaluate a quality of service (QoS) metric as actually perceived by end users and computes a preplanned restoration scheme to recover from failures. We discuss the numerical implementation, the convergence and the solutions produced by the algorithm and show that the resulting network can provide the prescribed QoS guarantees for all failure states.     

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.     

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.     

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.     

New MPLS network management techniques based on adaptive learning

The combined use of the differentiated services (DiffServ) and multiprotocol label switching (MPLS) technologies is envisioned to provide guaranteed quality of service (QoS) for multimedia traffic in IP networks, while effectively using network resources. These networks need to be managed adaptively to cope with the changing network conditions and provide satisfactory QoS. An efficient strategy is to map the traffic from different DiffServ classes of service on separate label switched paths (LSPs), which leads to distinct layers of MPLS networks corresponding to each DiffServ class. In this paper, three aspects of the management of such a layered MPLS network are discussed. In particular, an optimal technique for the setup of LSPs, capacity allocation of the LSPs and LSP routing are presented. The presented techniques are based on measurement of the network state to adapt the network configuration to changing traffic conditions.     

MPLS网络中QoS路由算法研究

论文着重研究了MPLS网络中QoS路由算法的设计问题。MPLS协议本身提供了QoS路由的机制,但有效的QoS路由算法却是其实现的保证。论文首先推导出代价函数公式,然后在此基础上提出了最小代价路由算法(LCR),根据MPLS网络节点获得的信息计算满足特定的QoS需求条件的最小代价路径。在模拟环境中,通过与SPF算法对比,此算法在保持路径利用率和平衡网络负载等方面具有明显优势。     

一种基于分段共享的预测式错误恢复机制

In MPLS/GMPLS networks, a range of restoration schemes will be required to support trade-offs between service interruption time and network resource utilization. Although, the tradition protectionbased and reservation-based recovery schemes exist some merits,but they can not provide a good trade-offs. In this paper,we propose a Prognostic Segment-based Sharing Recovery Mechanism(PSSRM)for restoration of connection over shared bandwidth in a fully distributed GMPLS architecture. PSSRM can use QoS constraints such as bandwidth and recovery time to obtain the good trade-offs of recovery time and resource efficiency.     

基于MPLS的IP微移动性研究

为了对移动IP网络提供服务质量、流量工程、可扩展性等支持,MPLS与移动IP的结合成为可能的解决方案之一。该文首先分析了MPLS和微移动IP协议相结合研究的动机和二者结合的特点,然后对现已提出的两种典型方案进行了分析,并对方案的性能等进行了比较,提出了统一模型,最后分析了现在存在的问题,给出了可能的优化途径。     

A fair resource allocation protocol for multimedia wireless networks

Wireless networks are expected to support real-time interactive multimedia traffic and must be able, therefore, to provide their users with quality-of-service (QoS) guarantees. Although the QoS provisioning problem arises in wireline networks as well, mobility of hosts and scarcity of bandwidth makes QoS provisioning a challenging task in wireless networks. It has been noticed that multimedia applications can tolerate and gracefully adapt to transient fluctuations in the QoS that they receive from the network. The additional flexibility afforded by the ability of multimedia applications to tolerate and adapt to transient changes in QoS can be exploited by protocol designers to significantly improve the overall performance of wireless systems. This paper presents a fair resource allocation protocol for multimedia wireless networks that uses a combination of bandwidth reservation and bandwidth borrowing to provide network users with QoS in terms of guaranteed bandwidth, call blocking, and call dropping probabilities. Our view of fairness was inspired by the well-known max-min fairness allocation protocol for wireline networks. Simulation results are presented that compare our protocol to similar schemes.