基于遗传算法的全光组播路由

该文提出使用遗传算法优化组播业务放置进光网络的顺序,按照此顺序为业务构建组播树并选择波长,以最小化光网络中使用的波长数及组播链路数。比较了3种路由算法的优劣以及波长变换器对资源优化的改善作用。基于NSFNet网络的仿真证明组播能力节点只需占到全网节点数的一半就能达到很好的优化效果。     

智能光网络体系结构与服务功能的探讨

大容量、智能化、综合业务处理将成为传送网络未来的基本发展方向，本文着重对智能光网络的网络体系与结构、智能光网络拄制平面相关技术“硬智能光网络的网络服务功能进行探讨。     

组播技术在ASON网络中的管理模型

组播技术以往都是在IP网络中实现，但随着光交叉连接设备（OXC）的成熟和ASON技术的不断发展，其灵活的交叉连接能力使得在光层上引入组播技术成为可能。从ASON的管理角度出发，提出一种基于ASON的管理体系结构，并基于这个结构．提出了组播技术在ASON中的管理模型。     

ASON网络中新型业务的管理模型

当前,光网络正以空前的速度向前发展,尤其是ASON技术的不断成熟,使得在光网络中推出各种新型增值业务成为可能。文章从光网络管理体系的角度出发,提出了一种基于ASON网络的管理体系,并在此基础上设计了组播业务、OVPN业务和BOD业务的管理模型。     

网络编码及其在光组播中的应用研究

组播应用使光网络的带宽资源日趋紧张。网络编码具有提高带宽利用率、提升网络的吞吐量、改善网络负载均衡等优点。分析了网络编码的特点及其编码代价、传统路由面临的问题,讨论了将网络编码引入光组播,优化光组播路由、提高网络吞吐量和资源利用率的研究方法。     

光网络技术发展走向探讨

光网络技术的发展与电信运营商的需求有着密切的联系。如何降低网络的运行维护成本、简化网络结构以及向用户提供更多的新业务成为当前电信运营商不断思考的问题。而数据业务每年急剧地增长及在其基础上不断涌现的新业务更成为业界持续关注的焦点。光网络作为承载能力最强的电信网络将会面对越来越多的数据业务的接入和传送，所以如何在适应数据业务突发性特性的同时．又能很好地解决以上运营商正在思考的问题就是光网络未来发展的方向。     

刍议自动交换光网络的路由协议

自动交换光网络最大的特点就是以传送平面、管理平面为基础,引入智能控制平面技术,并且通过信令技术、路由技术以及自动发现技术,提高了光层资源控制的灵活性,同时也提高了网络的可扩展性与可用性,并且网络结构得到进一步简化,降低了运营成本。由此可见,自动交换光网络是未来的发展趋势。本文主要针对自动交换光网络的路由协议展开讨论,首先阐述其基本概念,然后对三种路由模式进行分析,最后介绍几种路由协议。     

基于业务的智能光网络生存性研究

目前对于智能光网络（ION）生存性方面的研究主要是针对光网络本身，基于静态的资源配置和管理机制对于快速变化的业务需求而言缺乏灵活性，难以满足未来智能光网络中复杂业务的需求。基于业务的智能光网络生存性策略，可以解决现有网络生存性策略与业务侧的生存性需求之间的差异。通过将对生存性需求的描述和定义从网络侧转移到业务侧，以业务对生存性的需求为核心，能很好地实现智能光网络中对生存性策略的控制和实现。     

光网络带宽管理

光纤通信网络的发展已从链路状网向网状网发展。这样一来，网络的带宽管理就变得越来越重要。电信骨干网和城域网由于其业务模型的不同，对带宽管理的定义和需求模式有着巨大的差异。带宽管理能力的大小和效率，直接影响着网络的业务传输、调度和生存能力。多业务传输平台概念的提出，将数据业务的管理和传统语音业务的管理首次统一在了同一平台上。而智能交换光网络（ASON）的提出则首次将信令的概念引入传统意义的传输网络中，使网络的带宽管理能力和方式都有了一个质的飞跃。光网络带宽管理并不像很多人所认为的那么单一而简单，它所涉…     

在SDON中面向成本优化的虚拟光网络映射方法

结合软件定义光网络和光网络资源虚拟化的技术背景,对虚拟光网络成本优化问题进行了深入研究。在软件定义光网络中采用软件定义光网络基础服务架构和网络资源抽象的虚拟光网络服务架构,通过引入虚拟光网络的映射模型,提出了虚拟光网络映射策略和虚拟光网络协同映射规划方法,解决了面向成本优化的虚拟光网络映射方法,可为未来光网络虚拟化技术的应用提供技术支撑。     

光网络中的一种基于虚拟源的动态多播保护算法

随着各种多播业务的不断出现,如何在网络的光层实现多播业务的可靠性传输已成为光网络研究中的一个热点问题,而多播保护算法是这一问题的核心.目前多播保护算法的研究都是在假设网络所有节点具有多播功能的条件下进行的,然而由于成本的限制,实际光网络往往是一个稀疏多播光网络,即网络中只有部分节点具有多播功能.针对这一问题,提出了一种基于虚拟源的动态多播保护算法.仿真结果表明:该算法不仅能在稀疏多播光网络中满足多播业务可靠传输的要求,还具有较高的网络资源的利用率和较低的时间复杂度.     

IPv6网络中组播路由--PIM技术研究

随着网络宽带用户和下一代互联网的发展,多媒体业务相关服务如网络电视(IPTV)需求的日益增长刺激了IP组播技术的普及和发展,使其成为新一代网络中不可缺少的关键技术.与单播应用相比,采用IP组播技术分发信息常常能从本质上减少整个网络对带宽的需求.文章从IPv6网络的各种组播技术入手,详细介绍了当前在实际网络中获得广泛应用的基于协议无关组播(PIM)的组播路由技术 ,重点介绍了域内组播路由中使用最广泛的PIM稀疏模式(PIM-SM).对整个PIM-SM组播路由协议在IPv6网络中的运行过程进行了论述,最后介绍了其在未来IPTV等网络应用中的前景.     

On Multicast Routing for Wavelength-Routed WDM Networks with Dynamic Membership

Future broadband networks must support integrated services and offer flexible bandwidth usage. In our previous work in [1], we explored the optical link control (OLC) layer on the top of optical layer that enables the possibility of bandwidth on-demand (BoD) service directly over wavelength division multiplexed (WDM) networks. Today, more and more applications and services such as video-conferencing software and Virtual LAN service require multicast support over the underlying networks. Currently, it is difficult to provide wavelength multicast over optical switches without optical/electronic conversions although the conversion takes extra cost. In this paper, based on the proposed wavelength router architecture (equipped with ATM switches to offer O/E and E/O conversions when necessary), a dynamic multicast routing algorithm is proposed to furnish multicast services over WDM networks. The goal is to join a new group member into the multicast tree so that the cost, including the link cost and the optical/electronic conversion cost, is kept as low as possible. The same algorithm can be applied to other wavelength routing architectures with redefinition of electronic copy cost. The effectiveness of the proposed wavelength router architecture as well as the dynamic multicast algorithm is evaluated by simulation.     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

Multicast with a new switching structure in optical networks

The emergence of new services demands for a multicast function in optical networks. At the same time, wavelength converters are introduced to increase the efficiency of wavelength usage. It is because of the high cost and complex architecture of optical multicast and wavelength conversion technology, that a new switch structure is introduced, in which optical splitters and wavelength converters are shared per-node. In order to accommodate this architecture, a multicast routing and wavelength assignment algorithm in a splitter–converter-sharing optical network and a changing link weight policy to balance network traffic are proposed. By extending RSVP-TE (Resource ReSerVation Protocol-Traffic Engineering) and OSPF-TE (Open Shortest Path First-Traffic Engineering), an optical multicast mechanism is provided, and message type, signaling flow, and finite state machine model are given. Simulations of NSFNET show that, when the number of splitters and converters are 50% and 12.5% of the full equipment respectively, the performance is close to the ideal case. Using a changing link weight policy can improve performance greatly, when there are enough splitters and converters.     

Online multicast routing with bandwidth guarantees: a new approach using multicast network flow

We present a new algorithm for online routing of bandwidth-guaranteed multicasts where routing requests arrive one by one without any prior knowledge of future requests. A multicast routing request consists of a source, a set of receivers, and a bandwidth requirement. Two multicast applications of interest are routing of point-to-multipoint label-switched paths in multiprotocol label switched (MPLS) networks, and the provision of bandwidth-guaranteed virtual private network (VPN) services under the "hose" service model. Without prior knowledge of multicast requests, offline multicast routing algorithms cannot be used. Online algorithms are needed to handle requests arriving one by one and to satisfy as many potential future demands as possible. Our new online algorithm is based on the idea that a newly routed multicast must follow a route that does not interfere too much with network paths that may be critical to satisfy future demands. We develop a multicast tree selection heuristic based on the idea of deferred loading of certain critical links. The algorithm identifies them as links that, if heavily loaded, would make it impossible to satisfy future demands between certain ingress-egress pairs. The algorithm uses link-state information and some auxiliary capacity information for multicast tree selection and is amenable to distributed implementation. Unlike previous algorithms, our algorithm exploits any available knowledge of the network ingress-egress points of potential future demands, even though the demands themselves are unknown. It performs very well.     

组播技术及其在光层的实现

带宽密集型的多媒体应用对现有网络提出了新的要求,组播技术有助于解决其在网络带宽和服务质量方面的问题,而在光层实现组播具有更简单、高效的特点.然而,光层组播由于光缓存、光分束和光波长变换等光器件的限制,呈现出和IP层组播不同的特点.对IP层和光层组播进行了讨论,分析了光层组播模型,并对稀疏光分束和稀疏波长变换的光网络组播路由提出了重路由到源和重路由到相关节点两种重路由方式.     

Dynamic multicast sharing protection algorithm based on fuzzy game in multi-domain optical network

Aiming at the problem of dynamic multicast service protection in multi-domain optical network, this paper proposes a dynamic multicast sharing protection algorithm based on fuzzy game in multi-domain optical network. The algorithm uses the minimum cost spanning tree strategy and fuzzy game theory. First, it virtualizes two planes to calculate the multicast tree and the multicast protection tree respectively. Then, it performs a fuzzy game to form a cooperative alliance to optimize the path composition of each multicast tree. Finally, it generates a pair of optimal multicast work tree and multicast protection tree for dynamic multicast services. The time complexity of the algorithm is O(k3m2n), where n represents the number of nodes in the networks, k represents the number of dynamic multicast requests, and m represents the number of destination nodes for each multicast request. The experimental results show that the proposed algorithm reduces significantly the blocking rate of dynamic multicast services, and improves the utilization of optical network resources within a certain number of dynamic multicast request ranges.     

Algorithms for multicast traffic grooming in WDM mesh networks

Several of the new applications in high-performance networks are of the multicast traffic type. Since such networks employ an optical network infrastructure, and since most of these applications require subwavelength bandwidth, several streams are usually groomed on the same wavelength. This article presents an account of recent advances in the design of optical networks for multicast traffic grooming in WDM mesh networks. The article addresses network design and session provisioning under both static and dynamic multicast traffic. Under static traffic conditions, the objective is to accommodate a given set of multicast traffic demands, while minimizing the implementation cost. Optimal and heuristic solution techniques for mesh network topologies are presented. Under dynamic traffic conditions, techniques for dynamic routing and session provisioning of multicast sessions whose objective is to minimize session blocking probabilities are explained. The article also presents a number of open research issues