中国铁通开展MPLS VPN业务的分析

MPLS VPN是一种基于MPLS技术的IP虚拟专用网络(IPVPN),是在网络路由和交换设备上应用MPLS技术,简化核心路由器的路由选择方式,利用结合传统路由技术的标记交换实现的IP虚拟专用网络,可用来构造宽带的Intranet及Extranet,满足灵活的业务需求。     

IP over WDM网光层QoS业务映射模型设计

在IP over WDM网络中,WDM光网作为底层传送网络,目前还不能完全解析IP层对业务QoS区分等信息.针对IP和WDM网络中两种不同的QoS机制,应用IP网络差分服务模式,通过UNI接口汇聚来自IP网络的流量,将其映射为光域中相似的业务需求,在光域中为不同QoS业务提供不同QoS保障的光连接通道,实现了WDM网络层的QoS区分服务.     

IP over WDM网中的策略路由算法

业务量工程允许管理者通过赋予业务主干不同的业务量工程属性来体现一定的管理策略,在为业务主干建立标记交换路径(LSP)时也应该考虑这些策略的影响,该文讨论了业务主干具有不同优先权属性时的 LSP建立问题,针对中断 LSP个数最少和中断业务量最小两种指标,分别提出不同的解决策略:最小连接数中断法(MCNIM)和最小连接带宽中断法(MCBIM),并在不同负载的动态业务下对所提算法进行了仿真研究,给出了仿真结果。     

MPLS—VPN技术及市场

1 什么是MPLS-VPN MPLS-VPN是一种基于MPLS(MultiprotocolLabel Switching,多协议标记交换)技术的IP-VPN,是在网络路由和交换设备上应用MPLS技术、简化核心路由器的路由选择方式、利用结合传统路由技术的标记交换实现的IP虚拟专用网络(IP-VPN),可用来构造宽带的Intranet、Extranet,满足多种灵活的业务需求。     

基于IP/MPLS城域网开展VPN业务

哈尔滨广电作为宽带城域运营商,网络定位在能够提供各种业务的综合、开放网络,支持包括公用和私用的VPN业务,固定比特率或可变比特率业务,实时或非实时业务,单播或组播业务等。同时,将业务承载在IP/MPLS的网络上,全网实现MPLS。下面根据我们网络建设的完成,谈一谈基于IP/MPLS城域网开展VPN业务的建网想法和经验。1MPLS的应用传统的IP网络是一种“尽力而为”的服务模型。随着信息化的进一步发展,基于Internet的业务出现     

IP over WDM 网络中的QoS机制

本文讨论了IP over WDM网络中的三种不同的光交换技术并分别对这三种交换技术中的QoS机制做了比较和分析。     

基于MPLS技术的IP VPN实现机制（上）

VPN(Virtual Private Network)虚拟专用网是从专网业务发展而来的。专网实际上就是企业的专用内部网。当企业需要将不同地点的内部网进行连接时(跨广域连接),就需要借助公网的资源。传统的跨广域专网,是通过具体的物理电路实现互联的,例如:SDH或PDH的TDM电路。由于这种方式公网的带宽     

IP/MPLS over WDM网中考虑链路 负载平衡的保护设计

利用网络链路资源被占用的部分信息实现保护资源共享,可以极大地改善网络对业务的丢弃性能.这对采用多协议标记交换(MPLS,Multiprotocol Label Switching)技术的IP over WDM网络来说,并不需要太大的代价.基于此,本文提出了在IP over WDM网中考虑通路保护的动态路由算法.对工作通路的选取,算法对选路成本和路由长度作了折衷考虑;而对于保护通路,则对其共享能力和路由长度作了权衡.仿真结果表明,本文算法不管是对业务的丢弃性能,还是对网络的链路负载平衡度,均取得了较满意的结果.     

在IP城域网中利用虚拟路由域技术组建VPN

本探讨了如何在IP城域网上利用虚拟路由域技术组建VPN的实现方案，并提出了一些在实现中应注意的问题。     

能提供VPN业务的光以太网

城域网作为骨干网和广域网在城市范围内的延伸，连接成千上万的城市用户，是提供新一代话音业务和数据业务的关键所在。由于要在城域网的边缘部署、设置和管理大量设备，所以城域网代表了运营商的大部分资本预算和经营预算。从目前中国电信、网通、联通已经实施和应用的城域网结构来分析，由于网络采用第三层的IP路由技术，网络中部署了大量的结构复杂的路由设备，这些设备大大加重了运营商的前期投资成本，也造成了数据业务投资大、收入低的现象。因此，如何降低城域网的运营成本是广大运营商关注的主要方面。许多业内人士认为成本经济的…     

基于IP over WDM的光城域网

提出了基于IP over WDM的光城域网方案,详细阐述了波长选路WDM光城域网的多级网络拓扑及波长配置方式,并分析了波长配置方式对波长选路由策略的影响。     

QoS aware traffic grooming and integrated routing on IP over WDM networks

In this article, we consider traffic grooming and integrated routing in IP over WDM networks. The challenges of this problem come from jointly considering traffic grooming, IP routing, and lightpath routing and wavelength assignment (RWA). Due to the high bandwidth of optical fiber, there exists a mismatch between the capacity needed by an IP flow and that provided by a single lightpath. Traffic grooming is therefore used to increase the network utilization by aggregating multiple IP flows in a single lightpath. However, traffic grooming incurs additional delays that might violate Quality-of-Service (QoS) requirements of IP users. In this work, the tradeoff between traffic grooming and IP QoS routing is well-formulated as a mixed integer and linear optimization problem, in which the revenue from successfully provisioning IP paths is to be maximized. Problem constraints include IP QoS, routing, optical RWA, and the WDM network capacity. We propose a novel Lagrangean relaxation (LGR) algorithm to perform constraint relaxation and derive a set of subproblems. The Lagrangean multipliers are used in the proposed algorithm to obtain a solution in consideration of grooming advantage and resource constraints simultaneously. Through numerical experiments and comparisons between the proposed algorithm and a two-phase approach, LGR outperforms the two-phase approach under all experimental cases. In particular, the improvement ratio becomes even more significant when the ratio of IP flow to the wavelength capacity is smaller.     

用MPLS技术实现IP over WDM

提出了一种全新的高速宽带组网技术－基于MPLS的IPoverWDM网络技术,并对其进行了深入研究。这个方案在光联网技术中综合了目前先进的MPLS流量工程控制技术,特别适合于由可重构的OADM和OXC组成的以数据业务为核心的互联网络系统,而且它为最终在IP路由器上直接提供WDM复用功能铺平了道路。     

WDM网络中支持QoS的路由与波长分配算法

针对波分复用(wDM)网络中的路由与波长分配问题。提出了一种支持服务质量(QoS)的约束搜索算法。基于多目标规划模型,这种搜索算法可为网络各节点创建路由表,根据路由表信息求出非支配路径集合,从而一次性完成寻找路由和分配波长两项任务。仿真实例证明了该算法的有效性。     

IP over WDM联合路由框架

研究了IPoverWDMdirectly所面临的三大基本问题 ,重点对IP和WDM的联合路由框架进行了研究 ,分析了三种模型以及其中所用到的协议以及协议扩展。并对联合路由的控制面问题进行了研究 ,着重分析了对MPLS TE进行适当的光扩展以实现统一的控制平面。     

Providing differentiated services for multi-class traffic in IP/MPLS over WDM networks

Providing differentiated services in IP/MPLS over WDM networks has attracted a lot of recent attention. This article extends the Path Inflation Control (PIC) policy recently proposed by us to provide differentiated services in IP/MPLS over WDM networks with traffic grooming. Three different algorithms are considered for provisioning differentiated services. The simulation results show that, with two of the three algorithms, the network cannot only provide differentiated services when the traffic load is high but also gives significantly lower blocking for the lower priority class traffic and for the overall traffic at low traffic loads.

IP over WDM网络中一种新型虚拓扑构造算法

对IP over WDM的虚拓扑设计算法进行了研究，选择网络整体流量的均衡性作为优化目标，提出了一种新型的虚拓扑构造算法。在算法中，选择负载分布方差作为评价流量均衡性的指标，并给出其定义和计算方法。主要针对拥塞概率性能，在光层和IP层将提出的新型虚拓扑构造算法与其他算法进行比较。在光层的算法比较部分，选择负载均衡启发式路由算法（RLBH，routing with load balancing heuristics）与提出的算法进行比较；在IP层的算法比较部分，选择固定路径最小拥塞路由算法（FPLC，fixed-path least-congestion）与提出的算法进行比较，并对比较结果进行了讨论。比较结果显示在拥塞概率性能方面，提出的新型虚拓扑构造算法优于RLBH算法和FPLC算法。     

An efficient mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks

This paper proposes an efficient overlay multicast provisioning (OMP) mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks. To facilitate request provisioning, OMP jointly utilizes a data learning (DL) scheme on the IP/MPLS layer for logical link cost estimation, and a lightpath fragmentation (LPF) based method on the WDM layer for improving resource sharing in grooming process. Extensive simulations are carried out to evaluate the performance of OMP mechanism under different traffic loads, with either limited or unlimited port resources. Simulation results demonstrate that OMP significantly outperforms the existing methods. To evaluate the respective influences of the DL scheme and the LPF method on OMP performance, provisioning mechanisms only utilizing either the IP/MPLS layer DL scheme or the WDM layer LPF method are also devised. Comparison results show that both DL and LPF methods help improve OMP blocking performance, and contribution from the DL scheme is more significant when the fixed routing and first-fit wavelength assignment (RWA) strategy is adopted on the WDM layer. Effects of a few other factors, including definition of connection cost to be reported by the WDM layer to the IP/MPLS layer and WDM-layer routing method, on OMP performance are also evaluated.     

Optical multicast over wavelength-routed WDM networks: A survey

With the rapid development of optical networking technology, it is now a realizable technique to support point-to-multipoint connections directly on the optical layer, giving rise to optical multicast. The topic of optical multicast has attracted much enthusiasm in recent years for the reason that it will not only make full use of the abundant bandwidth provided by optical fibers, but also take full advantage of multicast over the traditional point-to-point connection approach. In this paper, we present a comprehensive review of optical multicast over wavelength-routed WDM networks, covering the development of both data plane and control plane designs. In particular, we provide an up-to-date state-of-the-art review on the multicast routing and wavelength assignment problem. To the best of our knowledge, this is the most thorough and comprehensive review conducted so far on this topic in the literature.     

一种面向IP/GMPLS over WDM网络的优化综合路由算法

为了优化利用IP层和WDM层网络资源,在WDM网络集成辅助图模型的基础上,提出了一种面向IP/GMPLS over WDM网络的基于代价的优化综合路由算法,即CIR(Cost-basedIntegrated Routing).该算法将IP层和WDM层资源可用信息以代价函数形式给出,并将因网络拓扑结构和网络负载分布不均衡等产生的瓶颈链路以及带宽碎片问题也统一纳入考虑,由此将LSP建立问题转化为在集成辅助图上找出一条源、目的节点之间的最短通路问题.仿真结果表明:CIR算法有效地实现了IP和WDM两层资源的联合优化,提高了网络资源利用,降低了网络阻塞率.