Rerouting technique with dynamic traffic in WDM optical networks

In this paper, we have proposed an efficient wavelength rerouting algorithm for dynamic provisioning of lightpath. In wavelength division multiplexed (WDM) networks rerouting of lightpath can be used to improve throughput and to reduce blocking probability. We have proposed a shortest path wavelength rerouting (SPWRR) algorithm for dynamic traffic in WDM optical networks. The results have shown that SPWRR algorithm can improve blocking performance of the network. In this paper, low complexity algorithm has been developed which is used for the calculation of blocking probability of network. The proposed algorithm has also been applied on the realistic network such as NSFnet for calculation and optimization of blocking probability of the network.     

Routing Algorithms in WDM Networks under Mixed Static and Dynamic Lambda-Traffic

Dynamic traffic is becoming important in WDM networks. In the transition towards full dynamic traffic, WDM networks optimized for a specific set of static connections will most likely also be used to support on-demand lightpath provisioning. Our paper investigates the issue of routing of dynamic connections in WDM networks which are also loaded with high-priority protected static connections. By discrete-event simulation we compare various routing strategies in terms of blocking probability and we propose a new heuristic algorithm based on an occupancy cost function which takes several possible causes of blocking into account. The behavior of this algorithm is tested in well-known case-study mesh networks, with and without wavelength conversion. Moreover, Poissonian and non-Poissonian dynamic traffics are considered.     

基于D*思想的动态RWA算法研究

文章提出一种基于D*(D-Star)思想的启发式算法,求解波分复用(WDM)光网络中动态路由和波长分配(RWA)问题.将网络中各边代价与当前波长使用情况综合考虑,建立D*算法的估价函数,实现了WDM光网络中动态业务的高效分配.仿真结果表明,该算法能有效降低阻塞率,促进波长资源的合理分配,同时,其快速和智能特性也提高了网络故障环境下的生存性.     

光网络中一种快速动态负荷均衡的波长路由算法

针对波长路由网络中动态光链路建立问题,提出了一种快速动态波长路由算法(RWA)。在路由子问题上,通过动态改进最短路径算法(Dijistra算法)权值的设置,使之符合光网络中动态流量分布,并适时更新路由信息表来适时调整网络的流量分布,减轻网络负荷,实现一种负荷均衡的路径查找。在波长分配子问题上,提出一种通过动态调节变异和交叉算子的遗传算法(VMCR-GA),可以实现快速波长搜索和分配。通过在几个网络上的仿真分析,比采用普通遗传和D算法的波长路由算法性能优越,网络阻塞率可以降低10%,波长分配效率提高30%~50%,算法的收敛性也大大提高。     

基于多条件约束的ASON动态组播路由算法

在将自动交换光网络(ASON)建模成着色多重图的基础上采用综合成本策略,设计了一种新的最小综合成本路径计算算法,并结合组播成员的动态变化特性提出一种满足多条件约束的动态组播路由(DMRMC)算法,使组播路由和波长分配在同一过程内完成,且尽可能使组播树的综合总成本最小,同时局部优化波长转换次数、分光次数和不同波长的使用数量。仿真实验表明,本文算法有效可行,与采用单成本策略的组播算法相比,其取得了更低的综合成本和更好的连接阻塞性能。     

一种新型的动态路由和波长分配算法

本文讨论了WDM光网中，在动态业务流量和有限范围波长变换情况下的动态路由和波长分配（RWA）问题，基于Moone-Dijkstra算法，考虑到动态波长变换的可能和限制，提出了一种新型的、可实现动态最小代价路由和最佳虚波长通道的综合启发式算法（DMC－OVMP）。该算法对路由子问题和波长分配子问题既相互独立，又相互结合，优化了RWA，保证了网络信息传输的安全性。对中国教育和科研计算机网（CERNET）基于本算法进行了计算机仿真，实现了低的网络阻塞率。     

Ant Colony Optimization for Dynamic RWA in WDM Networks with Partial Wavelength Conversion

Dynamic routing and wavelength assignment (RWA), which supports request arrivals and lightpath terminations at random times, is needed for rapidly changing traffic demands in wavelength division multiplexed, (WDM) networks. In this paper, a new distributed heuristic algorithm based on ant colony optimization for dynamic RWA is put forward. We consider the combination of route selection and wavelength assignment as a whole using a multilayer-graph model. Therefore, an extended multilayer-graph model for WDM networks with limited wavelength conversion is presented. Compared with other RWA methods, the Ant Colony heuristic algorithm can achieve better global network optimization and can reduce communication overhead cost of the networks. Simulation showed that a lower blocking probability and a more rational wavelength resource assignment can be achieved.     

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.     

Lightpath Rerouting Algorithm to enhance blocking performance in all-optical WDM network without wavelength conversion

In this paper, we have proposed an efficient wavelength rerouting algorithm for dynamic provisioning of lightpath. In wavelength-division multiplexed (WDM) networks rerouting of lightpath can be used to improve throughput and to reduce blocking probability. We have proposed a Lightpath Rerouting Algorithm (LRRA) for dynamic traffic in WDM optical networks. The results have shown that LRRA can improve blocking performance of the network. In this paper, low complexity algorithm has been developed which is used for the calculation of blocking probability of network. The proposed algorithm has also been applied on the realistic network such as NSFnet for calculation and optimization of blocking probability of the network. The results have also shown that the proposed algorithm can be implemented to huge networks for good blocking performance of the network.     

Dynamic Multicast Session Provisioning in WDM Optical Networks with Sparse Splitting Capability

In this work, we study dynamic provisioning of multicast sessions in a wavelength-routed sparse splitting capable WDM network with an arbitrary mesh topology where the network consists of nodes with full, partial, or no wavelength conversion capabilities and a node can be a tap-and-continue (TaC) node or a splitting and delivery (SaD) node. The objectives are to minimize the network resources in terms of wavelength-links used by each session and to reduce the multicast session blocking probability. The problem is to route the multicast session from each source to the members of every multicast session, and to assign an appropriate wavelength to each link used by the session. We propose an efficient online algorithm for dynamic multicast session provisioning. To evaluate the proposed algorithm, we apply the integer linear programming (ILP) optimization tool on a per multicast session basis to solve off-line the optimal routing and wavelength assignment given a multicast session and the current network topology as well as its residual network resource information. We formulate the per session multicast routing and wavelength assignment problem as an ILP. With this ILP formulation, the multicast session blocking probability or success probability can then be estimated based on solving a series of ILPs off-line. We have evaluated the effectiveness of the proposed online algorithm via simulation in terms of session blocking probability and network resources used by a session. Simulation results indicate that our proposed computationally efficient online algorithm performs well even when a fraction of the nodes are SaD nodes.     

基于关键链路预测的动态路由和波长分配算法

 光网络中的路由和波长分配 （RWA）算法是NP难问题. 目前的解决方案大多是基于启发式算法或图论的,其计算复杂度往往随着网络规模的增加呈指数增长,而且链路阻塞概率建模也十分困难. 本文提出了一种基于“关键链路”预测机制的RWA算法,并综合考虑跳数和空闲波长数的因素,不仅通过链路层面,而且也从网络层面来解决RWA问题. 实验结果表明我们的算法可以实现很好的流量负载均衡和低的阻塞率,具有较小的计算复杂度.     

一种快速动态分布式光链路建立方法

提出一种改进的波长分配算法,用于波长路由光网络中快速动态分布式光链路的建立。该算法采用提前释放和超时释放两种波长和链路释放机制,减少了网络拥塞,更适合波长路由网络的实际运行规则。通过在美国自然科学基金网(NSF)上的仿真计算,与以前的研究结果相比,该算法可以减少网络的阻塞率8％,同时缩短了光链路建立的时间。     

总线形与环形全光网中波长转换器的配置算法研究

波长转换技术可以消除全光网络中的波长一致性限制,降低网络阻塞率,因而在数量有限时存在合理配置、使用波长转换器的问题,本文在推导、分析网络阻塞率的基础上,提出了一种用于总线形和环形全光网的波长转换器配置算法,并对该算法进行了计算机模拟。模拟结果表明本算法的配置结果得出的网络阻塞率与最佳配置时的非常接近,而本算法的时间复杂度仅为O（4H＋2w)。     

WRON中基于波长相关性的波长分配算法

基于节约网络资源和降低网络的阻塞率和波长分配代价的思想,在WRON网络的动态路由波长分配算法中考虑波长相关性.根据波长之间转换度变化,详细定义波长转换器的可转换波长之间的波长转换度,并定义了一个利用二进制数表示的空闲波长指示参数,利用该参数对链路上的空闲波长进行表示,用蚁群系统的蚁群波长信息素更新的计算公式来更新这个指示参数,简化波长分配的过程.通过仿真,证明本算法能够达到节约波长资源,降低网络的阻塞率和波长分配代价的目的.     

部分共享波长转换光网络动态路由的改进算法

提出了一种应用于部分共享波长转换（PWC）的波长路由光网络（WRON）中的基于节点阻塞的动态路由算法,它不需要共享复杂的波长转换信息,而是将各节点的阻塞特性考虑到路由过程中。为评价算法性能,在14节点的国家科学基金网（NSFNET）拓扑中进行了仿真。结果表明,新的路由算法显著改善了网络的阻塞性能和建路失败的概率,尤其是随着网络负载的降低,网络性能的改善更显著。     

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。     

一种基于QoS的无线Mesh网络DSR路由优化算法

无线Mesh网络(Wireless Mesh Network,简称WMN)是一种新型的高容量、高速率的分布式宽带无线网络,是下一代无线网络的关键技术。在综合考虑带宽、传输拥塞、网络吞吐量等方面因素,将博弈论的思想引入动态源路由(Dynamic Source Routing,简称DSR)算法中,提出一种基于博弈论的DSR路由优化算法,经分析与仿真表明,该路由能有效减小时延,提高数据传输效率,提升网络传输的服务质量(Quality of Service,简称QoS)。     

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.     

一种基于ASON的新型动态恢复路径建链协议

讨论了动态波长路由光网络的恢复路径提供问题，在联合可变权重路由选择(JVWR)算法的基础上重点对恢复路径建立时延进行了分析，通过对恢复路径建立过程中的非物理资源相关因素的考虑，基于ASON控制平面的分布式信令协议提出了前向并行建链协议(FPLSP)。理论分析和仿真实验表明，该建链协议对于减少恢复路径链路建立时延具有明显的效果。     

WDM疏导网络中一种新的多播业务路由算法

研究了波分复用(WDM)网状网中动态多播业务量疏导,提出一种新的辅助疏导模型,其可以描述当前网络资源状况和节点分光特点,并动态更新.进而提出一种有效的多播业务量疏导启发式算法(MGA),将业务的多播选路和波长分配同时完成.仿真表明,该算法在波长连续性限制、网络波长和节点收发器数目有限的情况下,具有较低网络阻塞率.