多粒度全光网中的多层联合路由

多粒度交换技术利用波带级路由以及光纤级路由，可有效降低光交叉连接器的复杂度。但多粒度交换增加了光网络的逻辑层次结构，使得网络中的路由与资源分配问题更为复杂，因此，在多粒度全光网中实现多层联合路由是提高网络性能的关键。本文对多粒度交叉连接结构进行了分析，并对多粒度全光网中的多层联合路由问题进行了研究。     

动态业务条件下多粒度全光网性能分析与研究

多粒度交换技术利用波带级路由以及光纤级路由,可有效降低光交叉连接器的复杂度。但多粒度交换增加了光网络的逻辑层次结构,使得网络中的路由与资源分配问题更为复杂,多粒度全光网中的多层联合路由机制是影响网络性能的关键。本文对动态业务下多粒度全光网中的资源分配策略进行了深入研究,比较了采用不同节点交换比例时网络的阻塞性能,分析了不同业务量时多粒度交叉连接节点的最佳波带粒度,并结合经济性对多粒度全光网的性能进行了综合分析。     

动态业务条件下多粒度全光网性能分析与研究

多粒度交换技术利用波带级路由以及光纤级路由，可有效降低光交叉连接的复杂度，但多粒度交换增加了光网络的逻辑层次结构，便得网络中的路由与资源分配问题更为复杂，多粒度全光网中的多层联合路由机制是影响网络性能的关键。本文对动态业务下多粒度全光网中的资源分配策略进行了深入研究，比较了采用不同节点交换比例时网络的阻塞性能，分析了不同业务量时多粒度交叉连接节点的最佳波带粒度，并结合经济性对多粒度全光网的性能进行了综合分析。     

知识窗

波带交换波带交换(WBS)是将多个波长组合在一起作为整体进行交换,由于在光交叉连接(OXC)中只使用一个端口,可减少端口数,降低成本。在波长路由网络中,OXC通常是单一粒度,仅在波长级进行交换,每个波长需要一个端口。波带交换网络则使用多粒度OXC(MG-OXC),可对波长、波带以至光纤进行交换和分插。MG-OXC包含波长交叉连接(WXC)、波带交叉连接(BXC)和光纤交叉连接(FXC)。按照交换结构的不同,可有多层结构的MG-OXC和单层结构的MG-OXC,前者的光交换结构包含独立的WXC、BXC和FXC3个部分,后者则具有一个公共的光交换结构。单层…     

多粒度光网络波带组合策略的研究

为了有效地传输不同波长粒度的业务,对多粒度光网络波带组合进行了研究。首先介绍了多粒度光网络的模型和光交叉节点,并在此基础上分析了多粒度交叉连接结构的两种结构,单层和多层多粒度交换结构。结合多粒度的交换结构,给出了几种波带组合策略,并对这些策略进行了分析和比较。     

动态业务条件多颗粒度交换光网络性能研究

本文研究了动态业务条件下基于波带、波长两级交换的多颗粒度光交叉连接节点(MG-OXC)的优化设计,并提出了一种适用于多颗粒度交换光网络(MG-ON)的动态路由、波长分配和业务分组(Traffic Grouping)算法.利用实际网络拓扑对上述MG-ON方案进行了数值仿真实验,比较研究了MG-ON与传统OXC节点构成的波长路由光网络(WRON)的动态业务阻塞率性能,结果表明MG-ON的网络性能可以满足动态业务的要求.     

采用OCDMA技术的全光网

提出了在未来全光网中采用OCDMA技术的实现方案。OCDMA可以和WDMA相结合,细化光交叉连接的颗粒,增强光通道层的灵活性,而且可以直接从现有网络升级;OCDMA还可以和OTDMA相结合,实现信令的全光处理和的帧定界,从而使OTDMA网无需复杂的同步,这将为光包交换的实现提供一种有效的手段。进一步的研究需要对全光网节点内的交换网络结构和路由协议进行深入考虑。     

全光网——光通信的发展方向

全光网(AON,all-opticalnetwork)以波长路由光交换技术和波分复用传输技术(WDM)为基础,它的网络节点由光分插复用器和光交叉连接器构成,能在光域上实现高速信息流的传输、交换、路由和故障恢复等功能。光交叉连接器(OXC)与光分插复用器(OADM)是全光网中最重要的网络器件,是真正实现全光网关键性功能的必要前提,也是目前国内外光通信器件厂商研究和开发的热点。本文结合全光网的发展,介绍了光交叉连接器(OXC)、光分插复用器(OADM)与掺饵光纤放大器(EDFA)的基本原理以及全光网的交换技术,对光通信网和传统通信网进行了比较与讨论,并介绍了我国和国外在全光通信网上的发展状况。     

采用OCDMA技术的全光网

提出了在未来全光网中采用OCDMA技术的实现方案。OCDMA可以和WDMA相结合，细化光交叉连接的颗粒，增强光通道层的灵活性，而且可以直接从现有网络升级；OCDMA还可以和OTDMA相结合，实现信令的全光处理和的帧定界，从而使OTDMA网无需复杂的同步，这将为光包交换的实现提供一种有效的手段。进一步的研究需要对全光网节点内的交换网络结构和路由协议进行深入考虑。     

基于监控系统的光网络多层协调保护

在现今尚未实现全光网络的情况下,文章对多层光网络保护提出了一种新的策略,即采用监控系统进行协调多层保护.该策略在不改变已有网络结构与协议前提下,能够很好地实现光网络多层之间的恢复和保护.仿真结果证明,监控系统在光网络多层协调保护中的应用既解决了光网络中多层无法协调恢复的问题,又利用监控功能实现了预先建立网络静态路由,大大减少了网络层恢复时间.     

智能多粒度光交叉连接节点的设计与实现

提出了一种新型多粒度光交叉连接(MG-OXC)的体系结构,它可以完成光纤、波带、波长的交换,以及不同粒度业务的上下话路.同时介绍了由三个真实多粒度光交叉连接节点与若干虚拟光节点所组成的智能多粒度光网络试验平台的设计与实现.实验平台支持动态的可配置的网络拓扑、自动的邻居发现、受限的波长、波带路由,以及光层快速的保护与恢复.     

光网络中的波带交换技术

波分复用光网络已成为广域骨干网最可行的体系解决方案.波带交换(WBS)因其能减小光交叉连接器的端口数、控制复杂性和连接费用等,引起了广泛的关注.文章指出了WBS和传统波长路由的不同之处,对WBS的两种多粒度光交叉连接器结构进行了分析.文中还提出了基于WBS的各种方案和光路成组策略,讨论了WBS网络中的波带转换和故障恢复问题.     

Dynamic routing and wavelength assignment in multi-granularity WDM networks

For the purpose of reducing the complexity and cost of optical large-scale cross-connect, wavelengths are grouped into wavebands or fiber to be switched as a single entity, which is called multi- granularity switching. However, it introduces more complexity into the routing and wavelength assignment problem. In this paper, we propose a novel graph model for describing the states of the multi-granularity switching WDM networks. Based on the model, the dynamic routing and wavelength assignment problems for multi-granularity traffic can be solved jointly, and different on-line wavelength grooming policies can be achieved simultaneously. By simulation, we compared the performance of our algorithms under different policy and different percent of fibers for fiber switching. The result proved that our algorithms yield better performance than those deal with the routing and wavelength assignment separately. This work was supported in part by NSFC Project No. 90104003, 60272023, 60372025 and National 863 project No. 2005AA122310.     

Routing and wavelength assignment with multigranularity traffic in optical networks

We propose a novel switching architecture of multigranularity optical cross-connects (MG-OXCs) for dealing with multigranularity traffic in the optical domain. MG-OXCs can cooperate with the generalized multiprotocol label switching (MPLS) control plane, which provides the advantages of cost reduction, better scalability in physical size, and unified traffic management. Detailed discussions are provided on the characteristics and implementation issues for the switching architecture. Based on the proposed MG-OXCs, two routing and wavelength assignment (RWA) with tunnel allocation algorithms are presented: dynamic tunnel allocation (DTA) and capacity-balanced static tunnel allocation (CB-STA). In the former, we use fixed alternate routing with k-shortest paths to inspect network resources along each alternate path for dynamically setting up lightpaths. For the latter, fiber and waveband tunnels are allocated into networks at the planning stage (or off-line) according to weighted network link-state (W-NLS). We will show that with the proposed algorithms, the RWA problem with tunnel allocation in the optical networks containing MG-OXCs can be solved effectively. Simulation is conducted on networks with different percentages of switching capacity and traffic load. The simulation results show that DTA is outperformed by CB-STA in the same network environment due to a well-disciplined approach for allocating tunnels with CB-STA.. We also find that the mix of the two approaches yields the best performance given the same network environment apparatus.     

DWDM光传送网中选路和波长分配

本文综述了密集波分复用（DWDM）光传送网中选路和波长分配（RAW）研究领域的最新研究成果。分析比较了固定路由和备用路由下不同RAW算法的性能,还讨论了不同情况下采用波长变换对网络性能的改善。     

智能光网络中的路由和波长分配问题

随着下一代智能光网络概念的提出，应用于传统光网络的路由和波长分配方法面临着许多新的挑战。本以自动交换光网络为代表，分析了智能光网络中不同类型连接的特点和实现路由和波长分配的控制软件模块，并着重从路由模式、多粒度分层选路、路由和波长分配算法、信令路由协议等几个方面出发，对智能光网络中的路由和波长分配问题进行了深入的探讨。同时提出了相应的解决方案。     

Adaptive routing and wavelength assignment method based on SDN

Routing and wavelength assignment is an important resource allocation method of all-optical network.Aiming at the problem of traditional method combined with the new architecture,an adaptive multi-objective routing and wavelength assignment method based on SDN was proposed,which could realize the allocation of link resources of all-optical network through self-regulation.Based on the SDN service function chain model,service scheduling time and link service quality were taken as the scheduling objective,routing and wavelength assignment problem was constructed as the 0-1 integer programming problem,meanwhile,binary hybrid topology particle swarm optimization algorithm was used to optimize the network resources for optimal scheduling.The simulation results show that the proposed method is superior to the traditional classical algorithms in the test of recovery time,blocking rate and resource utilization.     

Link-State-Based Algorithms for Dynamic Routing in All-Optical Networks with Ring Topologies

The increased usage of large bandwidth in optical networks raises the problems of efficient routing to allow these networks to deliver fast data transmission with low blocking probabilities. Due to limited optical buffering in optical switches and constraints of high switching speeds, data transmitted over optical networks must be routed without waiting queues along a path from source to destination. Moreover, in optical networks deprived of wavelength converters, it is necessary for each established path to transfer data from source to destination by using only one wavelength. To solve this NP-hard problem, many algorithms have been proposed for dynamic optical routing like Fixed-Paths Least Congested (FPLC) routing or Least Loaded Path Routing (LLR). This paper proposes two heuristic algorithms based on former algorithms to improve network throughput and reduce blocking probabilities of data transmitted in all-optical networks with regard to connection costs. We also introduce new criteria to estimate network congestion and choose better routing paths. Experimental results in ring networks show that both new algorithms achieve promising performance.     

Routing and time-slot assignment in optical TDM networks

Optical time-division multiplexing (O-TDM) networks can provide a finer bandwidth granularity than wavelength-division multiplexing networks, and will play an important role in future all-optical networks. Since optical buffers are expensive, a small buffer size will be the characteristic of O-TDM systems. This paper analyzes the problem of routing and time-slot assignment in O-TDM networks. The results lead to the proposal of a Dijkstra-like shortest-path routing scheme that intends to maximize the performance of an optical network with a small number of optical buffers. Performance evaluation of the proposed scheme is also presented.