波分复用全光网络路由和波长分配算法

本文根据波分复用全光网络路由和波长分配（ＲＷＡ）实现过程的不同把算法划分为两大类;路由和波长分配分解法和路由和波长分配并行法。对这两类分别讨论了动态和静态ＲＷＡ算法。     

一种波长转换受限WDM网络的动态路由和波长分配算法

本文基于分层图模型,提出了在节点波长转换范围受限和波长转换器数目受限情况下,解决WDM网络的动态路由和波长分配问题的一种算法.通过计算机仿真,研究了本算法的性能以及这两种波长转换受限情况对网络阻塞率的影响.     

多光纤ASON网络动态路由优化算法

本文研究了多光纤波分复用光网络中的动态路由和波长分配问题，提出了基于分层图模型的一种新的多光纤网络的动态路由优化算法，该算法将连接请求的建立转化为在分层图模型中为该请求寻找一条最优路径，这使得设计者可以同时考虑路由和波长分配的问题，从而取得更好的效果。模拟结果显示基于分层图模型的(MFD—RWA：MultiFiber Dynamic：Routing and Wavelength Assignment)算法优于传统的动态最短路径算法。     

波分复用全光网中的一种新的波长分配算法

研究了动态业务下，采用固定选路和备用选路的波分复用光传送网中的波长分配问题．提出了一种新的波长分配算法，新算法在已市算法的基础上进行了改进，与已有算法相比，该算法能更精确地描述波长分配对全厨状态的影响。计算机仿真表明，如果用阻塞率来衡量，该波长分配算法优于文献中已有的波长分配算法。     

一种波分复用全光网波长分配算法

研究了动态业务下，无波长变换的波分复用全光风采用固定选路时的波长分配问题，提出了一种中心式的波长分配算法－最小影响算法。该算法能精确地描述某个波长的分配对全网状态的影响，因而能够更有效地使用网络资源。计算机仿真表明，如果用阻塞概率来衡量，该波长分配算法优于文献中已有的典型算法。     

多光纤WDM网中支持QoS的波长重路由算法

在WDM网上，波长连续性限制会降低网络的信道利用率，增加光路建立请求的阻塞率。采用波长重路由技术可以减少波长连续性限制对网络性能的影响。该文采用波长图模型，对多光纤WDM网中支持QoS的波长重路由算法进行了探讨，提出一种支持QoS的波长重路由算法－－动态选择法，并采用两种网络模型，在不同负载的动态业务下对所提算法进行了仿真研究；仿真结果表明所提算法既满足了上层业务不同的QoS要求，同时又充分利用了有限的网络资源，使全网的平均阻塞率降低。     

全光网静态路由选择和波长分配的分层图算法

文章提出一种将路由选择和波长分配结合起来的启发式的路由选择和波长分配(RWA)算法．通过这种新的分层图算法和限制光跳距的加权系数来优化全光网的静态路由选择和波长分配，使建立光连接时所需的波长数达到最少．最后对实际的ARPANet等5种光网络进行了计算机仿真，证明了本算法比以前的算法有更好的性能．     

固定选路的波分复用全光网中的波长分配算法

该文研究了动态业务下,无波长变换的波分复用光传送网采用固定选路时的波长分配问题,提出了一种中心式的波长分配算法-最小影响算法。该算法能精确地描述某个波长的分配对全网状态的影响,因而能够更有效地使用网络资源。计算机仿真表明,如果用阻塞概率来衡量,该波长分配算法优于文献中已有的典型算法。     

一种波分复用全光网波长分配算法

研究了动态业务下 ,无波长变换的波分复用全光网采用固定选路时的波长分配问题 ,提出了一种中心式的波长分配算法—最小影响算法。该算法能精确地描述某个波长的分配对全网状态的影响 ,因而能够更有效地使用网络资源。计算机仿真表明 ,如果用阻塞概率来衡量 ,该波长分配算法优于文献中已有的典型算法     

多光纤波分复用网的一种新的备用路由算法

基于经典的LLR算法,研究了波分复用光网络的路由问题,提出了一种用于多光纤网的新算法—LLHR,该算法综合考虑了链路负载和路由跳数两个因素。文章深入研究了网络光纤数、备用路由数和网络负载对算法性能的影响。计算机仿真结果表明,与LLR算法相比,该算法能有效降低网络的阻塞率,提高网络的性能。     

Optimal Wavelength Assignment Algorithms for Permutation Traffic in Multi-Fiber WDM Ring Networks*

Permutation traffic occurs in a number of networking applications. In this paper, the problem of wavelength assignment for permutation traffic in multi-fiber WDM rings with and without wavelength conversion is considered. We focus on a special class of permutation traffic and analyze the bounds on the number of wavelengths required to establish the connections. Lower bounds and optimal algorithms are presented for all the cases. The results indicate that a small number of fibers is sufficient to provide most of the benefits that wavelength conversion provides for this class of permutation traffic.     

A Virtual Wavelength Translation Scheme for Routing in All-Optical Networks

This paper considers wavelength routed WDM networks where multiple fibers are used for each communication link. For such networks, the effect of wavelength translation can be achieved without explicit use of wavelength translators. We call this as virtual wavelength translation and study the routing issues considering dynamic lightpath allocation. Using multiple (or a bundle of) fibers for each link also allows us to have bundles of varying sizes to accommodate anticipated differences in traffic through different communication links of the network. The paper considers the blocking probabilities of all-optical networks when centralized and distributed lightpath allocation schemes are used.     

Dynamic Routing and Wavelength Assignment in Survivable WDM Networks

Dense wavelength division multiplexing (DWDM) networks are very attractive candidates for next generation optical Internet and intelligent long-haul core networks. In this paper we consider DWDM networks with wavelength routing switches enabling the dynamic establishment of lightpaths between each pair of nodes. The dynamic routing and wavelength assignment (RWA) problem is studied in multifiber networks, assuming both protection strategies: dedicated and shared. We solve the two subproblems of RWA simultaneously, in a combined way using joint methods for the wavelength selection (WS) and wavelength routing (WR) tasks. For the WS problem in contrast to existing strategies we propose a new, network state based selection method, which tries to route the demand on each wavelength, and selects the best one according to different network metrics (such as available channels, wavelengths per fiber and network load). For the WR problem we propose several weight functions for using in routing algorithms (Dijkstra or Suurballe), adapting dynamically to the load of the links and to the length of the path. The combination of different wavelength selection and routing (WS&WR) methods enables wide configuration opportunities of our proposed algorithm allowing good adaptation to any network state. We also propose the extension of the RWA algorithm for dedicated and shared protection and a new method for applying shared protection in dynamic WDM environment. The detailed analysis of the strategies demonstrate that our RWA algorithm provides significantly better performance than previous methods in terms of blocking probability whether with or without protection methods.     

波分复用光网络中的波长路由分配策略

路由选择和波长分配是WDM光传输网中非常重要的问题.本文结合交叉连接节点,提出了一种基于最短路径的动态路由选择方案;然后利用这种动态的路由选择策略,以网络的阻塞性能为优化目标分配波长,达到充分利用网络资源的目的.计算机仿真结果表明,无论在单纤或者多纤WDM光传输网络中,利用这种策略的RWA算法优于传统的固定路由和单纯动态路由算法     

Performance Analysis of Multi-Fiber WDM Network with Limited-Range Wavelength Conversion

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength conversion technology and wavelength converters play an important role in enhancing fiber utilization and in reducing the overall call blocking probability of the network. In this paper, we develop a new analytical model to calculate the average blocking probability in multi-fiber link networks using limited range wavelength conversion. Based on the results obtained, we conclude that the proposed analytical model is simple and yet can effectively analyze the impact of wavelength conversion ranges and number of fibers on network performance. Also a new heuristic approach for placement of wavelength converters to reduce blocking probabilities is explored. Finally, we analyze network performance with the proposed scheme. It can be observed from numerical simulations that limited range converters placed at a few nodes can provide almost the same blocking probability as full range wavelength converters placed at all the nodes. We also show that being equipped with a multi-fiber per-link has the same effect as being equipped with the capability of limited range wavelength conversion. So a multi-fiber per-link network using limited range wavelength conversion has similar blocking performance as a full wavelength convertible network. Since a multi-fiber network using limited range wavelength conversion could use fewer converters than a single-fiber network using limited range wavelength conversion and because wavelength converters are today more expensive than fiber equipment, a multi-fiber network in condition with limited range wavelength conversion is less costly than a single fiber network using only limited range wavelength conversion. Thus, multi-fiber per-link network using limited range wavelength conversion is currently a more practical method for all optical WDM networks. Simulation studies carried out on a 14-node NSFNET, a 10-node CERNET (China Education and Research Network), and a 9-node regular mesh network validate the analysis.     

Performance Study of Distributed Wavelength Reservation Protocols within Both Single and Multi-Fiber WDM Networks

Distributed wavelength reservation protocols are employed to dynamically set up and tear down lightpaths in WDM networks. In this paper, discrete event-driven simulations are carried out to investigate the performance of different protocols under both single and multi-fiber circumstances. Simulation results indicate that the behavior of these protocols varies noticeably between single and multi-fiber networks. Discussions on these results are also presented. It is found that the preferred scheme in the literature, which adopts backward reservation with random wavelength selection, does well in single-fiber scenarios. But this scheme fails to be excellent in multi-fiber scenarios since it cannot take full advantage of multiple fibers. Then, we extend the reservation protocols for multi-fiber networks and propose a novel wavelength selection policy called Maximum-Availability policy. Results show that our scheme will give an outstanding performance in both single and multi-fiber networks.     

Dynamic Routing and Wavelength Assignment in Optical Networks by Means of Genetic Algorithms

We propose a novel genetic algorithm for solving the dynamic routing and wavelength assignment (DRWA) problem in wavelength-routed optical networks. The algorithm not only obtains low call blocking probability, but it also employs a very short computation time. Moreover, it is capable of providing fairness among connections, that is, to offer approximately the same quality of service (in terms of blocking probability) for all source-destination node pairs. Since requirements on optical network availability are highly severe, we also propose an extension of the algorithm to provide fault-tolerance capability at the optical layer. It is achieved by means of protection, where each optical connection request is provided with a pair of lightpaths (a primary and a backup lightpath). Again, the genetic algorithm proves to be highly efficient, in this case, at performing routing and wavelength assignment of pairs of lightpaths.