A Distributed Routing and Wavelength Assignment Algorithm for Online Multicast in All-Optical WDM Networks

Routing and wavelength assignment for online real-time multicast connection setup is a difficult task due to the dynamic change of availabilities of wavelengths on links and the consideration of wavelength conversion delay in WDM networks. This paper presents a distributed routing and wavelength assignment scheme for the setup of real-time multicast connections. It integrates routing and wavelength assignment as a single process, which greatly reduces the connection setup time. The proposed routing method is based on the Prim’s MST (Minimum Spanning Tree) algorithm and the K-restricted breadth-first search method, which can produce a sub-minimal cost tree under a given delay bound. The wave-length assignment uses the least-conversion and load balancing strategies. Simulation results show that the proposed algorithm is suitable for online multicast connection establishment in WDM networks.

Directional Routing Algorithm for Deep Space Optical Network

With the development of science, economy and society, the needs for research and exploration of deep space have entered a rapid and stable development stage. Deep Space Optical Network(DSON) is expected to become an important foundation and inevitable development trend of future deepspace communication. In this paper, we design a deep space node model which is capable of combining the space division multiplexing with frequency division multiplexing. Furthermore, we propose the directional flooding routing algorithm(DFRA) for DSON based on our node model. This scheme selectively forwards the data packets in the routing, so that the energy consumption can be reduced effectively because only a portion of nodes will participate the flooding routing. Simulation results show that, compared with traditional flooding routing algorithm(TFRA), the DFRA can avoid the non-directional and blind transmission. Therefore, the energy consumption in message routing will be reduced and the lifespan of DSON can also be prolonged effectively. Although the complexity of routing implementation is slightly increased compared with TFRA, the energy of nodes can be saved and the transmission rate is obviously improved in DFRA. Thus the overall performance of DSON can be significantly improved.

Distributed multicast routing algorithm with dynamic performance in multimedia networks

The delay and DVBMT problem is known to be NP-complete. In this paper,an efficient distributed dynamic multicast routing algorithm was proposed to produce routing trees with delay and delay variation constraints. The proposed algorithm is fully distributed,and supports the dynamic reorganizing of the multicast tree in response to changes for the destination. Simulations demonstrate that our algorithm is better in terms of tree delay and routing success ratio as compared with other existing algorithms,and performs excellently in delay variation performance under lower time complexity,which ensures it to support the requirements of real-time multimedia communications more effectively.

QoS multicast routing algorithm based on GA

The multicast routing problem with multiple QoS constraints in networks with uncertain parameters is discussed, and a network model that is suitable to research such QoS multicast routing problem is described. The QMRGA, a multicast routing policy for Internet, mobile network or other highperformance networks is mainly presented, which is based on the genetic algorithm(GA), and can provide QoSsensitive paths in a scalable and flexible way in the network environment with uncertain parameters. The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or nearoptimal solution within few iterations, even for the network environment with uncertain parameters. The incremental rate of computational cost can be close to a polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated by using simulations. The results show that QMRGA provides an available approach to QoS multicast routing in network environment with uncertain parameters.

Elastic Resource Allocation for Multi-Granularity Multicasting Traffic in OFDM-Based Optical Networks

With the increasing requirements of the multicast services in the whole data traffic service, the optical multicast technology becomes a key technology supporting wide bandwidth and high speed multicasting communication. The transmission efficiency, capacity and robustness of optical multicast network can be further improved by introducing network coding technology into optical multicast networks. Meanwhile, facing to demand of emerging rate-variable multi-granularity multicast service, a multi-path transmission scheme based on network coding for routing and spectrum allocation (RSA) is proposed. It can not only allocate spectrum resources effectively and flexibly for various-rate multicast traffic, but also balance the network load, improve network throughput and reduce transmission blocking rate. In this paper, RSA problem is decomposed into two subproblems, namely routing allocation based on network coding and spectrum allocation based on maximum spectrum first (MSF) strategy, which are solved sequentially. Simulation experiments are carried out to analyze transmission performance with proposed RSA scheme. The simulation results show that the proposed RSA mechanism can allocate spectrum resources efficiently and flexibly for multi-granularity multicast traffic. Compared with RSA schemes based on shortest path tree (SPT) and minimal spanning tree (MST), the proposed RSA scheme is more efficient for spectrum resource utilization and load balancing, and spectrum resource is saved more than 20%.

Study on Wevelength Allocation Algorithm and Its Optimization of WDM All Optical Networks

In this paper, a new wavelength allocation algorithm based on the minimum number of hops(MNH) is applied to derive the relationships of wavelength requirement with different network parameters. A new modification of the algorithm using the Monto Calo Method is proposed. The results show that using this algorithm, the wavelength requirement of the networks can be optimized. This paper also discuss the effect of multi link optimization of the networks. This approach can further reduce the wavelength requirement and improve the efficiency of resource of the networks. The numerical results show that choosing adequate number of additional links is a key issue to optimize the networks. These algorithms and their results can be used to optimize network design for WRONs.

A Heuristic Algorithm for P-Cycles Configuration in WDM Optical Networks

Aiming at minimizing spare capacity for optical WDM networks, we propose a new heuristic algorithm for preconfigured protection cycle (p-cycle) design. Numerical results show that the spare capacity obtained by our new algorithm is very close to the optimal solution.

Blocking Probability in All-Optical WDM Network Using IMCA

The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced analytical model is proposed to evaluate the blocking performances in topology network and to improve the performances of reduction of blocking probability. The variation of probability is based on the wavelength and load used in the network. The conversion is carried out with the support of optical backbone of the inherent flexibility of the network using the proposed IMCA in Sparse-Partial Wavelength Conversion (SPWC) architecture. It reduces the number of converters significantly with efficient process and provides placement scheme of wavelength converters in the network. The proposed model utilizes the network with the assignment and routing of wavelength using dynamic process of assignment algorithm. The proposed model provides dynamic and static routing process with the range limit to have a minimum conversion for the same probabilities of blocking. The proposed system analysis and the simulation results show the better performances in faster coverage, minimum number of conversions, blocking probability improvement for high load.

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(k3 m2 n), 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.

Network coding based all-optical multicast in WDM networks

Wavelength division multiplexing （WDM） has been becoming a promising solution to meet the rapidly growing demands on bandwidth. Multicast in WDM networks by employing free wavelength is an efficient approach to saving bandwidth and cost. However, the free wavelength may not identical between different hops in a multicast light-path, particularly in heavy load optical WDM networks. In order to implement multicast applications efficiently, a network coding （NC） technique was introduced into all-optical WDM multicast networks to solve wavelength collision problem between the multicast request and the unicast request. Compared with the wavelength conversion based optical multicast, the network coding based optical multicast can achieve better multicast performance with paying lower cost.

WDM全光网络中Multicast的寻径与波长分配算法

在WDM全光网络中实现实时Multicast功能是计算机网络的应用要求,也是现代计算机网络的重要特征。该文提出了一种在WDM全光网络中实现实时Multicast的算法。该算法以辅助的波长图为基础,将寻径与波长分配统一进行,构造满足延迟约束的、具有较低成本的Multicast树,实现Multicast功能。

Resource Allocation Using SPA Based on Different Cost Functions in Elastic Optical Networks

Routing, modulation and spectrum allocation in elastic optical networks is a problem aiming at increasing the capacity of the network. Many algorithms such as shortest path algorithm can be used as the routing section of this problem. The efficiency of these algorithms is partly based on how the cost of each link is defined. In this study, we considered several basic metrics in cost of network links and compared their effects on the network capacity. In particular, the static costs and the dynamic costs were evaluated and compared. For dynamic scenarios, compared to static scenarios, at least one additional factor, the usage of the links, was added. We further considered a new factor that is based on probability of accommodating the signal at a given time in any given link. The results show that, among them, the shortest path algorithm provides the least blocking probability when the cost is a combination of link length and the abovementioned possibility/usage of the link.

On the stability of multicast flow aggregation in IP over optical network for IPTV delivery

The stable multicast flow aggregation （MFA） problem in internet protocol （IP） over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access touters attached to the optical network, in which each head end can provide a set of programs （IP multicasting flows） and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of access touters changed dynamically. We introduce a program correlation matrix to describe the preference of end users＇ requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first （MCPF）, is presented and compared with the extended least tree first （ELTF） algorithm which is topology- aware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage.

WDM全光网络中实时组播的分布式路由与波长分配算法

在WDM网络中 ,由于每条链路上可用波长是动态变化的 ,在考虑波长转换延迟的条件下 ,实现实时组播连接的路由与波长分配是十分困难的 假定WDM网络中每条链路有多根光纤 ,只有部分结点具有波长转换器且波长转换时间是不可忽略的 ,据此提出了一种用于建立实时组播连接的分布式路由与波长分配算法 该算法以Prim最小生成树算法为基础 ,生成一棵满足给定延迟时限的最小成本树 当最小成本树不能包括所有目的结点时 ,对剩余目的结点生成一棵最短延迟树 ,然后合并两棵树得到一棵组播树

WDM网络中实时组播的分布式路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。该文提出了一种用于建立实时组播连接的分布式路由与波长分配算法。该算法将路由与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法和K-度宽度优先搜索方法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和负载平衡策略。

一种IP/DWDM光因特网中的组播路由算法

研究了IP/DWDM光因特网的集成QoS(QualityofService)组播路由与波长分配算法·给定组播请求与用户QoS需求,提出的算法基于遗传算法GA来构造一棵柔性QoS组播树,并基于波长图方法对组播树进行波长分配,一体化考虑路由选择和波长分配问题,从而使QoS组播树费用和用户QoS满意度都趋近优化·该算法还考虑了IP/DWDM光因特网的负载均衡问题·仿真实验表明,算法是可行和有效的·

多约束条件下WDM光网中多播选路和波长分配算法

在光层构建多播选路和波长分配时,必须考虑一些约束条件。主要的约束条件有以下4种:稀疏分光器配置约束、波长连续性约束、能量损伤约束及稀疏波长转换器约束。目前,研究人员只是针对其中一个或两个约束条件进行了算法研究。该文在详细分析各种约束条件之后,提出了一种基于多约束条件下多播选路和波长分配启发式算法。最后在CERNET和NSFNET两种网络拓扑上进行了仿真实验。根据算法仿真结果可以得出该算法可以有效地解决多约束条件下的多播路由及波长分配问题。

WDM全光网络中的路由及波长分配

在全光网络中,光信号在全光域内传输,避免了光-电转换带来的延迟,因此,全光网支持高数据率传输并提供巨大的网络容量。WDM(波分多路复用)技术的采用使得高速光传输线路与低速终端处理设备之间能够相互兼容。论文探讨了WDM全光网中的路由及波长分配问题,对各种常用算法进行了详细的分析,并提出了对一种新型的用于WDM网络上的实时组播请求的分布式RWA算法进行改进的意见。

MPLS over WDM光互联网中多优先级标记交换路径路由算法研究

该文针对分层图模型的局限,设计了结点光收发器数受限的MPLSoverWDM光互联网的扩展分层图。提出并研究了MPLSoverWDM光互联网中具有不同QoS约束的多种优先级标记交换路径的路由算法——区分综合路由算法(DifferentiatingIntegratedRoutingAlgorithm,DIRA)。该算法综合考虑了对标记交换路径QoS的满足和网络资源的优化利用。与目前实用的WDM光网络路由算法的性能仿真对比表明,DIRA在提高网络总的吞吐量,降低有时延约束标记交换路径的阻塞率方面,性能更优。

IP/DWDM光因特网中一种基于人工免疫算法的QoS组播路由算法

本文提出了一种IP/DWDM光因特网中基于人工免疫算法的QoS组播路由算法,当QoS组播请求和需求区间给定时,能够找到一棵基于QoS的柔性费用近优组播路由树。该算法基于人工免疫算法构造QoS组播路由树,并基于波长图对树进行波长分配,将路由和波长分配集成到一个过程中,同时考虑了负载平衡。仿真结果表明,算法为IP/DWDM光因特网中的组播应用构造的QoS组播路由树是可行和有效的。