IP over Optical网络联合流量工程研究

对IPoverOptical网络的流量工程进行了深入的研究。问题,给出了两种流量工程体系结构,重叠流量工程和联合流量工程,然后对这两种流量工程体系进行了比较,并给出了联合流量工程的实现框图以及需要解决的关键问题。     

GMPLS网络的流量工程扩展

流量工程技术的目的是优化网络运行性能,实现网络资源的最优化利用。而且随着网络迅速发展,网络流量的激增特别是突发流量的增加都对作为骨干网的光网络的性能提出新的要求。本文首先简要介绍MPLS网络的流量工程机制,然后重点介绍GMPLS路由协议的流量工程扩展,以及两种不同约束路由计算机制,分别是在线进行路径计算的基于约束最短路径优先算法和离线路径计算的基于设计路由算法。     

基于GMPLS的光网络保护恢复的研究

文中首先比较了GMPLS和SDH／SONET的保护和恢复机制，接下来阐述了GMPLS用于增强网络的保护与恢复能力的信令机制，最后对网络的保护和恢复机制如何使用GMPLS信令来实现进行了详细的分析和讨论．     

基于GMPLS的智能光网络流量工程研究

自动交换光网络已经成为下一代光网络的发展方向,而其控制平面的分布式连接管理功能则是实现光网络智能性的关键。本文介绍了自动交换光网络的功能结构,在此基础上系统论述了分布式连接管理的功能要求,详细分析了分布式的呼叫和连接处理的实现过程,并给出了具体的参考流程和状态转移模型。     

GMPLS在PON中的应用

首先对无源宽带光接入网(PON)技术和通用多协议标签交换协议(GMPLS)进行回顾,然后根据现有PON技术的缺陷和目前全光智能网的研究趋势提出一种全新的PON模式,即基于GMPLS协议的无源宽带光接入网技术(GMPLSPON)。介绍了GMPLSPON的技术概念,对GMPLSPON的关键技术进行初步的探讨。     

Implementing Stochastic Preplanned Restoration with Proportional Weighted Path Choice in IP/GMPLS/WDM Networks

IP over WDM networking and related GMPLS standards, appear to be attractive solutions for today's and future Internet applications due to their ability to handle multiple traffic flows independently of one another, and reserve wavelengths to carry a large number of aggregated flows. Another advantage of these solutions is the simplified IP over WDM stack, that provides all the vital network functionalities, including network reliability. The paper investigates the use of the stochastic preplanned restoration scheme with proportional weighted path choice (SPR-PW) to design reliable and efficient IP/GMPLS/WDM networks. Upon the disruption of a primary flow determined by a link failure, one of the associated preplanned secondary paths is readily selected by the SPR-PW scheme to continue the flow transmission. The selection of the secondary path is performed on a probabilistic base, without requiring time-consuming coordination among the restoration attempts of the disrupted flows. As a result of this stochastic selection, the SPR-PW scheme has the potential to yield short recovery times. In addition, the SPR-PW required signaling, upon and before the failure occurrence, is limited, which makes SPR-PW a scheme suitable for highly dynamic traffic scenarios, in which flows are subject to frequent changes. The paper describes the SPR-PW scheme as it is applied to cope with physical link failures, depicts a possible implementation of such a scheme using standard IP/GMPLS signaling capabilities, and numerically demonstrates two properties of the SPR-PW scheme, i.e., low blocking probability and short restoration times.     

GMPLS技术及其路由算法

通用多协议标签交换（ GMPLS）是由多协议标签交换（MPLS）发展而来,它是MPLS向光层扩展的必然产物.GMPLS将时隙、波长和光纤端口作为标签用子数据转发,通过采用扩展的信令、路由协议和新增的链路管理机制以适应对智能光网络进行动态控制和传送信令的要求,动态提供网络资源并增加网络的存活性.本文着重比较了GMPLS与MPLS,说明其如何改进MPLS,并提供了GMPLS在光控制平面的应用解决方案.最后,谨慎分析了GMPLS的前景及其需要解决的问题     

Strategy for Dynamic Routing and Grooming of Data Flows into Lightpaths in New Generation Network Based on the GMPLS Paradigm

This paper reports on a novel strategy and related algorithm for realizing dynamic routing and grooming into wavelengths of data flows (label switched paths, LSPs) in new generation optical networks based on generalized MPLS (GMPLS). The method allows arbitrary granularities of LSPs. The new generation network is modeled as a multi-layer network consisting of an IP/MPLS layer and an optical layer. In particular, the proposed solution adopts a dynamic routing algorithm based on the Dijkstra algorithm, that makes use of a weight system, integrated with a suitable method for grooming LSPs into wavelengths based on the packing criterion, thus harmonizing the features of MPLS packet flows whose bandwidth vary in a continuous range of values, with the optical world, where the wavelength bandwidth ranges according to discrete values. The weight system is based on the concepts of least resistance routing that allows to evenly distribute the traffic at the MPLS layer, while packing improves the use of optical resources by favoring more filled wavelengths with respect to the emptier ones. To assess the validity of the proposed solution a simulation model has been realized. The results obtained by simulation show that the packing criterion allows reducing the refused bandwidth from two down to about four times, for a network load of 70% and 55%, respectively, when compared with the alternative method named spreading. The dependence of the proposed solution on bandwidth granularity has been also investigated. Moreover, in order to demonstrate the superior performance of the proposed routing solution, a comparison between the proposed strategy with relevant solutions known in the literature, based on either a single or multi-layer approach, is also reported. In order to perform the comparison, all the reference routing solutions that have been considered adopt the packing method for LSP grooming into the lightpaths. The results show that our solution outperforms the others in terms of amount of traffic that can be on-line accommodated. For instance, assuming a blocking probability of 10^–3, the proposed solution is able to further reduce the refused bandwidth of the best routing algorithm considered in the analysis by a factor of three times, thanks to the knowledge of optical resource availability.     

基于GMPLS的流量工程研究

随着因特网业务的迅猛发展，流量工程技术正成为优化网络资源和提高网络性能的关键技术。本文介绍了流量工程的基本概念度其重要性，详细分析GMPLS对MPLS的路由协议和信令协议所作的流量工程扩展，并讨论了基于GMPLS网络中实现集成流量工程的可能性和优势。     

通用标签交换网络中的故障处理

对GMPLS网络中的故障处理的过程进行了介绍,并对不同业务恢复方法的性能差异进行了分析和对比。     

MPLS网络中基于流量工程实现QoS的研究

这里介绍了基于MPLS流量工程的QoS保证机制,并以TCP和UDP为业务模型,以吞吐量为性能指标对MPLS网络中采用流量工程情况下的QoS性能进行了分析。     

Performance Evaluation of Multi-Layer Traffic Engineering Enabled IP-over-ION Networks

Recently, network operators started implementing traffic engineering (TE) techniques in their network. These TE techniques typically involve a single layer (for example, the IP/multi-protocol label switching (MPLS) layer). Although single-layer TE (STE) can improve the network performance (e.g., throughput, quality of service (QoS)), this improvement is bounded by the available capacity in that network layer. The evolution towards intelligent optical networks (IONs) allows further increasing the improvements achievable by the TE techniques, by involving more than one layer in the TE actions. Multi-layer TE (MTE) occupies network resources in a smart way and optimizes the QoS since it dynamically reconfigures the logical topology in the upper layer by properly updating the optical connections in the underlying optical layer. However, the performance of the network is impacted by the configuration scheme adopted by MTE. Therefore, in this paper, we focus on analyzing the influence of the MTE configuration scheme on the MTE behavior, and evaluate the network performance by studying simulation results obtained from a realistic IP-over-ION network.     

An Architecture for Differentiated Protection Against Single and Double Faults in GMPLS

In the context of an optical network GMPLS can be used to provide network robustness to faults through end-to-end path protection techniques. In this paper, we present a dynamic distributed model supporting five different classes of protection, including protection against single and double fault, with and without sharing of backup bandwidth. Beyond link and node failures we also consider protection against shared risk link group (SLRG) failure. In this paper, we briefly describe the protection model and the underlying algorithms for route selection and backup bandwidth sharing. After that we face the following issue: Which subset out of the five possible protection classes is convenient for an operator to support on the same network infrastructure? To answer this question it is fundamental to have a clear view of the trade-offs between the costs and the performances associated to each class. To achieve that we carried out an extensive performance analysis by means of simulations. For each protection class, we evaluated two fundamental performance metrics: the recovery probability under multiple faults, and the average per-demand resource usage. On the basis of such results, we are able to identify some basic guidelines driving the choice of the more convenient subset of protection classes to be implemented within a single network.     

用于Mesh光网络快速保护恢复的GMPLS信令机制的扩展

分析了Mesh光网络保护机制和恢复机制,并对GMPLS信令机制进行了扩展,给出了扩展后实现保护恢复的协议格式和信令流程,最后依据实验数据给出扩展的GMPLS信令机制的保护、恢复时间的仿真结果.     

A New Analytical Model of Shared Backup Path Provisioning in GMPLS Networks

As GMPLS and its supporting set of protocols develop into aviable control plane for optical networks, an important function that they will need to support will be the protection and restoration function that has been a major feature of legacy optical networks. A network with a robust set of protection and restoration mechanisms will be able to support data traffic while allowing faster recovery from failures than can be obtained using layer 3 rerouting. Several models have been proposed for protection with GMPLS using shared backup paths. This previous work has not investigated the effect on recovery time critical to the service or the number of backup paths that are required to meet a desired level of performance. Using both restoration time and recovery blocking probability, we have developed a new analytic model for GMPLS-based recovery in M : N protection groups. Furthermore, we show that smaller backup paths can be reserved by capturing the effect of multiple failures in the case of M : N shared protection with revertive mode in an optical network with a GMPLS control plane.     

GMPLS网络中基于约束的最短路径优先算法

对多种基于约束的最短路径优先算法设计思想进行了分析对比,选择了一种适用于GMPLS网络的路由算法,而且阐述了满足我们需求的设计方案。     

GMPLS中光层的保护和恢复机制

主要讨论了GMPLS信令对MPLS的扩展,通过对GMPLS新增的LMP协议和通告消息的讨论来解决故障的4个步骤,最后结合GMPLS根据现有光层的保护和恢复机制对保护交换和恢复的特点及实现方法进行了详细的讨论。     

Traffic Measurement for Traffic Engineering in IP/MPLS Based Telecom Core Networks

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MPLS在Internet流量工程中的应用

首先回顾了IP网络流量工程的概念和所面临的挑战,然后讨论了MPLS(多协议标记交换)的基本概念和发展,指出了MPLS巨大的流量工程能力和主要功能,最后着重分析了MPLS在IP网络流量工程中的应用.     

Models of Restoration Probability in WDM Networks Employing Active Restoration

The ever-increasing demand for network bandwidth makes network survivability an issue of great concern. Lightpath restoration is a valuable approach to guaranteeing an acceptable level of survivability in WDM optical networks with better resource utilization than that of its protection counterpart. Active restoration (AR) is a newly proposed lightpath restoration scheme [M. Mostafa et al. OSA Journal of Optical Networking, vol. 3, no. 4, pp. 247–260] that combines the best of protection and reactive restoration while avoiding their shortcomings. In this paper, we conduct detailed performance analysis on the restoration probability of AR-based WDM networks. In particular, analytical models of restoration probability are developed respectively for networks with full-wavelength conversion capability and for networks without wavelength conversion capability under different backup path searching schemes. Based on the new models, we investigate the effects of wavelength availability, wavelength conversion capability, path length as well as backup path seeking methods on the restoration probability.