基于SDH的ASON中光组播技术的研究

文章首先简要分析了基于SDH的自动交换光网络(ASON)中光组播的功能需求,然后讨论了在基于SDH的ASON环境下实现组播的几种业务建立模型,最后从功能框架、信令扩展和实现流程等方面对具体实现方案进行了探讨。     

基于SDH的ASON中光组播技术的研究

文章首先简要分析了基于SDH的自动交换光网络(ASON)中光组播的功能需求，然后讨论了在基于SDH的ASON环境下实现组播的几种业务建立模型，最后从功能框架、信令扩展和实现流程等方面对具体实现方案进行了探讨。     

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。     

基于GMPLS控制平面的ASON组播

阐述了利用自动交换光网络(ASON)实现组播的意义,分析了ASON组播的GMPLS信令协议、路由协议,给出了通过改进ASON现有技术实现组播的可行方案,包括信令过程和路由算法,得出结论并对ASON组播的前景作出展望。     

基于超图模型的多域ASON损伤感知组播路由算法

如何在缺乏全局信息的条件下构建安全可靠的组 播树,是智能光网络分域管理后引入的一个新问 题。针对此问题,通过建立新型的多域智能光网络超图模型,在考虑物理或攻击损伤的约束 条件下,利用 基于超路径的域间超树构建方法,结合K最短路径策略,提出了 一种基于超图模型的多域ASON损伤感知 组播路由算法,并进行了实例分析。本文算法在完成多域组播路由建立与波长分配的同时, 具有较低的时间复杂度。通过测量K值、组播规 模、波长数量及分配策略、域数量对网络平均连接阻塞率的影响,实验结果表明,本文算法 是有效的且取得了较好的阻塞性能,同时建议多域ASON组播规模大小应与域的数量保持一 定的比例均衡。     

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。     

基于ASON的智能光网络关键技术的研究

随着市场需求和光网络技术的飞速发展,自动交换光网络ASON作为一种智能光网络的主流模式,得到了迅速的发展.文中深入细致地探讨了以ASON为模型的智能光网络的系统结构、"硬光"及"软光"等关键技术.重点分析了ASON的软光技术,包括ASON分布式管理技术、控制平面技术和ASON软件选路算法,并对智能光网络技术的发展作了展望.     

一种光网络中统一网管的实现方案

自动交换光网络(ASON)是下一代光网络的研究热点,随着ASON技术的不断成熟和实现,ASON网络的网管实现变得更为迫切,文章通过对ASON网管功能进行分析,提出了一种光网络中的统一网管实现方案。     

下一代光传送网ASON

提出当今解决光传送网所面临问题的方法,是采用既能低成本建网又能智能化完成交换连接的自动交换光网络( ASON );介绍回顾了光传送网 ASON 技术的产生和取得的成果,以及 ASON 中几种关键控制平面技术的发展情况;阐述了 ASON 控制平面与传统传送网的本质区别、管理平面智能化管理特点所带来的 3 种优点,以及传送平面中光交叉连接( OXC )的 6 种主要交换结构、发展方向和存在的主要问题;最后综述了新一代基于数字同步系列(SDH )提供多种业务、集成传输、交换和路由功能的多业务传送平台(MSTP )技术,并描述其新功能和远期目标。     

ASON的引入策略和演进方案

自动交换光网络(ASON)是构建下一代光网络的核心技术之一,将它引入传送网已成为必然趋势。ASON的引入策略和演进方案是业界,特别是运营商关注的重要问题。文章分析了ASON引入和逐步演进需要考虑的问题,并在此基础上对ASON的引入和演进进行了分析。     

一种支持扇出分割能力的光组播调度算法研究

组播调度是影响光组播分组交换节点吞吐量的重要因素.针对“一次发送”模型下的光组播调度算法对阻塞的源组播实行全部丢弃的缺点,文章基于节点共享有限波长转换器的光分组交换结构,提出了一种支持扇出分割能力的光组播调度算法,该算法采用随机丢弃阻塞的源组播复制的方法,有效地提高了端口资源的利用率.仿真结果表明,该算法与已有算法相比...     

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.     

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.     

一种改进的时延受限低代价光组播路由算法

针对光网络时延受限光组播路由计算复杂度高的问题,提出一种基于改进的和声搜索求解时延受限光组播路由的算法。论文通过引入自适应的和声记忆保留率及微调概率提高和声算法搜寻到全局最优光组播树的能力;算法设计了一个能够保持备选光组播树多样性的动态适应度函数以扩大光组播路由的搜索范围;同时,算法在初始化和声库时采用精英保留策略简化和声迭代过程。仿真结果表明,提出的改进算法能够求得代价更低的光组播路由,且算法在较大光网络规模下具有较好的收敛稳定性。     

Multicast Flow Aggregation in IP over Optical Networks

It is widely believed that IP over optical networks will be a major component of the next generation Internet However, it is not efficient to map a single multicast IP flow into one light-tree, since the bandwidth of an IP flow required is usually much less than that of a light-tree. In this paper, we study the problem of multicast flow aggregation (MFA) in the IP over optical two-layered networks under the overlay model, which can be defined as follows: given a set of head ends (i.e. optical multicasting sources), each of which can provide a set of contents (i.e. multicast IP flows) with different required transmission bandwidth, and a set of requested content at the access routers (i.e. optical multicasting destinations), find a set of light-trees as well as the optimal aggregation of multicast IP flows in each light-tree. We model MFA by a tri-partite graph with multiple criteria and show that the problem is NP-complete. Optimal solutions are designed by exploiting MFA to formulate an integer linear programming (ILP), with two parameters: the multicast receiving index alpha and the redundant transmitting index beta. We also propose a heuristic algorithm. Finally, we compare the performance of MFA for different combination of alpha and beta via experiments and show our heuristic algorithm is effective for large-scale network in numerical results     

Performance analysis of optical multicast in a new switching structure

The emergence of new services demands multicast function in optical network.Because of the high cost and complex architecture of multicast capable (MC) node, splitter-sharing switch structure is introduced in which the light splitters are shared by all input signals.To accommodate to this situation, by extending resource ReSerVation protocol-traffic engineering (RSVP-TE) and open shortest path first-traffic engineering (OSPF-TE), a new optical multicast mechanism is provided and the signaling flow and its finite state machine model are given.At the same time, a multicast routing algorithm in splitter-sharing optical network and a changing link weight policy to balance network traffic are proposed.Simulations in NSFNET show no matter with or without wavelength converters, when the number of splitters is 25% of that demanded by traditional MC nodes, the multicast performance has been close to the ideal circumstance.Wavelength converters and changing link weight help much in improving the traffic performance when the number of splitters is adequate.     

Virtual-node-based multicast routing and wavelength assignment in sparse-splitting optical networks

This paper investigates several problems associated with optical multicast routing and wavelength assignment in sparse-splitting optical networks for interactive real-time media distribution. Unfortunately, the constrained multicast routing with optimized wavelength assignment leads to NP-complete condition. Thus, in this paper, a virtual-node-based multicast routing algorithm is first proposed to satisfy the requirements of interactive real-time multicasting as well as the constraints from underlying optical networks. For the constructed multicast tree, we then associate an effective wavelength assignment algorithm. The experimental results show that the proposed algorithm combination performs well in terms of (1) the wavelength channel cost, (2) the maximum variation of inter-destination node delays, (3) the signal quality, and (4) the number of wavelength conversions.     

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.     

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.     

WDM网状网络中一种动态多播自适应业务疏导算法

光多播业务需要消耗大量的WDM光网络带宽资源,业务疏导是光多播网络降低业务请求阻塞率和提高带宽资源利用率的有效方法。提出了一种新型光多播疏导节点结构,研究了疏导端口优先的多播业务疏导算法(TGPFA)和新建光树优先的多播业务疏导算法(TCLFA),进而提出了一种能够适应网络资源变化的动态多播业务疏导算法(ADMGA)。结果表明,在网络资源有限的情况下,ADMGA算法能取得较低的请求阻塞率和带宽阻塞率,获得较好的网络性能。