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。     

支持不同可靠性要求的WDM网状网业务量疏导算法

WDM光网络中不同的业务流具有不同的可靠性要求，本文研究动态业务下如何解决此类业务量疏导问题，提出了一种在WDM网状网中支持多种可靠要求的业务量疏导算法(MRTG)。仿真结果表明该算法具有很好的性能。     

波分系统链、环状网络动态业务疏导的波长选择算法及仿真

针对基于业务疏导的WDM网络模型的两种不同的网络优化目标,提出并仿真了在已用波长优先情况下6种波长选择算法方案,计算机仿真结果表明,基于概率模型的业务疏导波长选择算法和基于业务起止位置的带宽负载度算法具有较好的性能。最后指出了这些算法的应用领域。     

WDM光网络中的业务量疏导

波分复用（WDM）技术在主干传送网中巳广泛应用，WDM光网络的研究进展也非常迅速，光网络中的业务量疏导定义为复用、解复用和交换低速率业务流到大容量的光路中的行为。介绍了WDM光网络的业务量疏导的重要性，研究方法及其最新研究进展情况。     

Design of grooming architectures for optical WDM mesh networks: limited grooming with electronic wavelength conversion

In this article, we consider the problem of traffic grooming in optical wavelength division multiplexed (WDM) mesh networks under static traffic conditions. The objective of this work is to minimize the network cost and in particular, the electronic port costs incurred for meeting a given performance objective. In earlier work, we have shown the benefits of limited grooming switch architectures, where only a subset of wavelengths in a network are equipped with expensive SONET Add Drop Multiplexers (SADM) that provide the grooming functionality. In this work, we also consider the wavelength conversion capability of such groomers. This can be achieved using a digital cross-connect (DCS) in the grooming switch to switch low-speed connections between the SADMs (and hence, between wavelengths). The grooming switch thus avoids the need for expensive optical wavelength converters. Based on these observations, we propose a limited conversion-based grooming architecture for optical WDM mesh networks. The local ports at every node in this architecture can be one of three types: an add-drop port, a grooming port that allows wavelength conversion or a grooming port that does not allow wavelength conversion. The problem studied is: given a static traffic model, where should the different ports be placed in a network? We formulate this as an optimization problem using an Integer Linear Programing (ILP) and present numerical results for the same. We also present a heuristic-based approach to solve the problem for larger networks.     

WDM疏导网络中的基于连接的动态恢复

针对WDM网络中单链路出错的生存性流量疏导问题,提出了一种基于连接的动态恢复机制(DRAC).DRAC不预留任何资源,当链路出错时,通过在网络中动态的发现资源来对错误进行恢复,将一个出错连接转发到一条新的多跳路径.仿真结果显示,提出的这种动态恢复机制拥有很高的恢复概率.     

Analysis of multi-hop traffic grooming in WDM mesh networks

Traffic grooming is an essential functionality of WDM optical networks to provision multi-granularity subwavelength connections. Depending on the number of lightpaths allowed in a connection route, traffic grooming can be classified as single-hop traffic grooming (SH-TG) and multi-hop traffic grooming (MH-TG). MH-TG is more general and resource-efficient than SH-TG, because it allows connections from different source-destination pairs to share the bandwidth of a lightpath. In this paper, we propose a MH-TG algorithm, namely the fixed-order multi-hop (FOMH) grooming algorithm, based on the fixed-alternate routing approach. We introduce the grooming node selection (GNS) problem in MH-TG and propose three grooming policies, namely exhaustive sequential (ES), limited-hop sequential (LHS) and load sharing (LS) policies, to address the GNS problem. These policies represent different trade-offs among blocking probability, computational complexity and transceiver requirements. Given that the analysis of MH-TG is a relatively unexplored area, we propose an analytical model to evaluate the blocking performance of MH-TG using FOMH and the LS grooming policy. To address the multi-layered routing and multi-rate connection characteristics of traffic grooming, we introduce a novel multi-level decomposition approach in our analytical model which decomposes traffic at four different levels, namely alternate path, connection route, lightpath and link levels. The model also addresses various factors that affect connection blocking probability. These factors include wavelength continuity constraint, channel continuity constraint and route dependence. The Erlang fixed-point approximation method is used to solve the analytical model. Numerical results show that analytical results match well with simulation results. We also evaluate the effect of the grooming policies, the number of virtual hops (lightpaths) within a connection route and the number of alternate paths on the performance of the grooming algorithm.     

Simulation-based SONET ADM optimization approach for dynamic traffic grooming in WDM optical networks

The article addresses a simulation-based optimization approach for allocation of ADMs in WDM optical networks with stochastic dynamic traffic. Since ADMs are expensive, it is desirable that if each node in WDM optical networks can use a minimum number of ADMs to achieve a near-ideal performance. In this article, first, the utilization statistics of ADMs are gathered by simulation. Then, ADMs are allocated based on the utilization statistics. In this respect, a simple sorting mechanism is used. The distinguished feature of the proposed approach is that it shows the way to allocate ADMs at the nodes of WDM optical networks with stochastic dynamic traffic. The experimental results ensure that the proposed approach can solve the problem of allocating ADMs in practical WDM optical networks considering stochastic dynamic traffic.

WDM抗毁网状网络中的业务量疏导算法

研究具有抗毁能力的WDM网状网中的业务量疏导设计问题，提出几种以网络吞吐量为优化目标的启发式算法，并通过计算机仿真分析，证实了基于最大化资源利用率的算法具有很好的性能。     

WDM网络中动态流量的资源效率疏导策略

为了解决波分复用(WDM)网状网络中的动态流量疏导问题,基于收发器节约辅助图模型,提出了一种资源效率疏导策略.它同时考虑收发器和波长链路两种网络资源的有效利用,根据当前的网络状态动态改变疏导策略,使网络不会由于某一种资源的缺乏而导致阻塞所有流量,避免了另一种资源因富余而造成的浪费,从而两种资源都能得到充分利用.在辅助图模型中,根据两种资源的可用数目比值,对各条边设置不同的权值函数,可轻易地实现该策略.仿真结果证明,不管是收发器资源受限还是波长资源受限,该策略都能取得较好的性能,降低了网络的阻塞率.     

Wavelength retuning without service interruption in an all‐optical survivable network

This paper proposes a new wavelength retuning (WRT) scheme in an all‐optical WDM network. Compared with the existing WRT schemes developed for all‐optical networks, which can alleviate the wavelength‐continuity constraint but cannot avoid service interruption or data loss, the proposed scheme is able to alleviate the wavelength‐continuity constraint and reduce the connection blocking probability with no service interruption to the on‐going traffic. This is achieved by allocating two routes, one for active path and one for backup path, to each incoming connection request and conducting WRT only on the backup path. The backup path provides an alternate path in case of a failure, while the active path carries traffic under normal conditions. Thus, WRT on the backup path will not cause any impact on data transmission. An optimal backup path WRT scheme and a heuristic algorithm are developed and the performance evaluation on the proposed schemes is presented. The simulation results show that the proposed optimal scheme reduces the connection blocking probability by 46.8% on average, while the proposed heuristic scheme reduces the blocking probability by 28.3% on average, all compared with the scheme without WRT. Copyright © 2009 John Wiley & Sons, Ltd.     

A heuristic solution to SONET ADM minimization for static traffic grooming in WDM uni-directional ring networks

In recent years, minimization of add-drop multiplexers (ADMs) in wavelength division multiplexing (WDM) optical networks has gained lots of attention in both the research and commercial areas. This motivates the research presented in this paper. A heuristic algorithm is formulated for static traffic grooming in WDM uni-directional ring networks with an eye to minimize the number of required ADMs. The distinguished feature of the proposed heuristic is that it pairs up the calls of a given static traffic to approach the solution. The proposed heuristic is compared with the previous approach with same network configuration and traffic matrix to establish its effectiveness.     

Performance analysis under dynamic loading of wavelength continuous and non‐continuous WDM networks with shortest‐path routing

The performance of WDM networks using shortest path routing is studied under wavelength continuous (WC) and non‐continuous (NWC) constraints and dynamic traffic loading. Approximate analytical models are presented for the performance studies of such systems. Results of numerical calculations based on these models and simulations are given for different network topologies for the purposes of comparison. These analytical and simulation results are used to study the performance of these WDM networks under dynamic traffic loading. Copyright © 2001 John Wiley & Sons, Ltd.     

一种基于WDM光网络的静态波长路由优化算法

研究了WDM光网络中的静态波长路由问题,基于负载的均衡可以改善网络的性能这一事实,提出了一种优化的路由算法(O-Spread算法),文中进行了算法仿真,结果表明优化算法与传统的最短路由算法相比,能够有效地减小网络对于波长数目的需求。     

A comparative path establishment study on routing performance of MLR WDM optical networks

In this paper, we investigate the effect of path establishment method priorities over routing performance in mixed line rate (MLR) wavelength division multiplexed (WDM) optical networks. The survivable routing with rate and wavelength assignment (SRRWA) problem is presented and an efficient shared backup path protection solution is proposed. We prepared detailed simulation scenarios with all possible prioritizations and observed their performances. The simulation results show that assigning higher priority to single hop methods as compared with multi‐hop methods yields better performance. In both methods, it has been observed that assigning higher priority to grooming reduces the communication cost and the traffic blocking ratio while enhancing the resource utilization.     

一种用于光网络的高效业务疏导辅助图及动态业务疏导算法

利用辅助图,研究了光网络中的业务疏导技术。为解决传统的辅助图存在着模型复杂、波长通道的带宽利用率不高等问题,提出一种新的业务疏导辅助图,能够更有效地利用已有波长通道,避免低效的路由;为了降低动态业务疏导算法的复杂度,提出了一种简化的k最短路径算法,并以此为基础提出了多种疏导策略。仿真结果表明,本文提出的辅助图及其业务疏导算法,可以有效地减少阻塞率。     

Grooming of dynamic traffic in WDM star and tree networks using a genetic algorithm

The advances in WDM technology lead to the great interest in traffic grooming problems. As traffic often changes from time to time, the problem of grooming dynamic traffic is of great practical value. In this article, we discuss the dynamic grooming of traffic in star and tree networks. A genetic algorithm (GA) based approach is proposed to support arbitrary dynamic traffic patterns, which minimizes the number of ADMs and wavelengths. To evaluate the algorithm, tighter bounds are derived. Computer simulation results show that our algorithm is efficient in reducing both the number of ADMs and wavelengths in tree and star networks.     

全光波长转换技术在混合WDM/OTDM网络节点中的应用与实验进展

简单分析了未来全光通信网中光波分复用(WDM)和光时分复用(OTDM)技术组合使用的必要性,讨论了各种全光波长转换技术在混合的WDM/OTDM网络结点中的应用,并结合实验进展介绍了各种转换技术的原理和特性。     

多播格状WDM光网络中流量疏导的一种启发性算法

波分复用技术的开发应用及网络业务信息的多样化促进了多播技术的应用和发展.由于网络中波长带宽与节点间业务信息需求之间的巨大反差,使流量疏导成为必要,以节约网络资源和成本.但多播的出现使流量疏导算法变得更复杂多样.本文提出了对多播格状网络中的静态流量进行有效疏导的一种启发性算法,并取得较为优化的结果.     

Protecting Multicast Sessions in WDM Networks with Sparse‐Splitting Constraints

In this letter, we study the multicast protection problem in sparse‐splitting wavelength‐division multiplexing (WDM) optical network, and propose a novel multicast protection algorithm called the shared source‐leaf path‐based protection (SLPP) algorithm. Unlike the proposals in previous studies, the backup paths derived by SLPP can share wavelength with the primary tree in sparse‐splitting WDM networks. Simulations are used to evaluate the effectiveness of the SLPP algorithm.