基于冗余度和方差的P-Cycle圈构造算法的研究

铁路光传送网络是高速铁路地面基础设施的神经中枢,为避免网络故障给铁路运营带来巨大损失,重点研究光传送网P-Cycle(Pre-configured Cycle)保护技术,提出在圈扩展时以所有候选圈上未保护工作容量的方差、冗余度两个指标为比较标准的RVPA(Redundancy and Variance Based P-Cycle Construction Algorithm)算法。圈扩展的过程中,算法将选择方差与冗余度能同时满足条件的候选圈作为本轮扩展圈,有效限制了完成保护的P-Cycle圈个数;圈扩展停止条件中,当UPL与参数M、冗余度的大小关系满足条件时,则停止圈扩展,从而限制圈上节点数,使圈个数与圈长度得到有效均衡;在仿真过程中,利用泛欧网络拓扑COST239对RVPA算法进行仿真,并对比分析不同M值下的性能。仿真结果表明,在相同空闲资源与待保护工作容量设定下,参数M取0.5时效果最优,并且RVPA算法的保护容量效率、所需圈的个数、算法整体耗时、总冗余度均优于已有的POCA(P-Cycle Optimization Configuration Heuristic Algorithm)算法。

抗毁网状WDM网络中的光纤级P-Cycles优化设计

为降低保护切换代价和提高故障恢复时间,提出了以光纤级P-Cycle来实现网络保护;研究了工作路由与光纤级P-Cycle放置联合优化的设计问题,给出了ILP数学模型。为降低计算的复杂度,采用了一种简单有效的方法:根据跳数预先选择工作路由候选集及环的有效性和长度预先选择P-Cycle候选集。仿真结果表明光纤级P-Cycle设计相比于波长级P-Cycle设计保护切换代价大大降低。

Mesh网络p-cycle的快速配置方法

该文提出了mesh冗余网络中快速配置p-cycle保护环的方法。算法从两个方面有效地提高配置速度:一方面在一次比较搜索过程中,配置一个多容量p—cycle环,而不是仅配置一个单位容量环;另一方面,将已有算法基于圈的搜索策略,改进为基于通路的搜索策略。这样可以有效地防止大量的搜索信息汇聚到一个节点,降低配置速度。当改为通路搜索后,原来汇聚到一个节点的处理,可分散到多个相邻节点进行并行处理,这将有效地加快配置速度。通过仿真表明,该钟法具有同已有算法相当的恢复率,但所需的搜索趟数性能却能获得大幅度的改善,同时也不显著增加备用容量的消耗。结果表明网络规模越大,本文算法的优势越明显。

静态p-cycles双链路故障保护配置准则

提出并证明了如果一个网络拓扑中的每个链路都可以配置2个仅边相交于该链路的p-cycles,则该网络中的任意2个链路故障均能得到完全保护.同时提出了基于此准则的启发式算法,并进行了仿真。结果表明,在该配置准则中,采用共享p-cycles能减少所需的保护容量.

静态p-Cycles双链路故障保护策略的研究

p-Cycles应用在WDM格网中可以得到高的容量利用率和快速保护倒换时间,本文给出了一种格网生存性有关容量问题的 研究方法,即孤立节点分析法,提出了p-Cycles在双链路故障情况下的保护策略,并建立了以保护容量需求作为优化目 标的p-Cycles优化设计模型。

格网中p-cycles重配置的快速实现算法

提出了一种用于双链路故障恢复和为动态业务提供保护的p-cycles重配置启发式算法.该算法可以提供网络生存性设计和网络管理的高效性和简洁性,并能提供快速的恢复操作.仿真结果表明,这种算法用于双链路故障恢复的重配置容量冗余度可达74%,平均计算时间为48ms;用于增量重配置的双故障冗余度为118%,计算时间为81ms.基于该算法的业务恢复可以满足大多数业务的最低可中断时间要求.分析表明该算法亦适用于动态业务的p-cycles重配置.

抗毁WDM光网络中SRLG约束下p-Cycles配置算法

基于共享风险链路组(SRLG,shared risk link group)和P圈(P-Cycles,pre-configured cycles)的概念,研究了SRLG约束下p-Cycles的构造问题,引入SRLG完全分离p-Cycles的概念,基于SRLG的简单p-Cycles构造算法和获得更多p-Cycles的SRLG约束下的圈扩展算法提出的SRLG约束下的p-Cycles配置算法(SCAA),实现在光网络中优化配置SRLG完全分离的p-Cycles。通过计算机仿真表明,SCAA最小容量配置方案可以预留更少的网络资源,而SCAA优化容量配置方案可以实现p-Cycles快速配置容量,SCAA算法可以保障配置SRLG分离p-Cycles的高保护效能,使网络具备单SRLG故障恢复能力。

PTN网络基于p-Cycle的业务保护算法

随着科技的不断进步,为更好地适应IP数据业务的需求,分组传送网PTN逐渐取代传统网络TDM,本文主要研究了基于p-Cycle的PTN网络业务保护算法,试图其能够达到节约PTN网络运行成本,提高网络带宽利用率及保护倒换效率的重要作用。

Shared p-cycles design for dual link failure restorability in optical WDM networks

Pre-configured cycles （p-cycles） can attain high capacity efficiency and fast protection switching times in wavelength division multiplexing （WDM） networks. This article proposes the weighted straddling link algorithm（WSLA） for generating a subset of all cycles that can guarantee 100% restorability in case of dual link failure, and give an integer linear programming（1LP） formulation that solves the shared p-cycles design problem minimizing the total spare capacities. Numerical result shows that our method can achieve 100% dual link failure restorability with acceptable spare capacity. The larger standard deviation of demand set and the larger node degree network, the better the shared p-cycles scheme performs.

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.

Novel P-Cycle protection strategy for asymmetric traffic in mesh optical networks

A novel prefigured-cycle(P-Cycle)algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks.The proposed algorithm was simulated in a Pan-European COST239 network environment under an asymmetric dynamic traffic model.The experimental results show that the proposed algorithm has lower capacity redundancy and higher utilization rate of configured resources than traditional P-Cycle methods.Network performance can be improved when implementing this algorithm under single-link failure circumstances.The system behavior is analyzed under different traffic volumes and the configuration strategy is also investigated for the heavyload and light-load networks respectively.

Shared-p-cycles method for design of survivable WDM networks

In future high-capacity wavelength division multiplexed(WDM)optical networks,the failure of a network component such as a fiber link can lead to severe disruption in the networks’traffic.Hence,it is imperatively important to provide fast and full protection in WDM optical networks.In this paper,we propose a new approach,called shared preconfigured protection cycles(shared-p-cycles),for the design of survivable WDM networks.We develop an integer linear program(ILP)formulation to solve the problem of shared-p-cycles design for WDM networks with and without wavelength conversion.Numerical results show that the shared-p-cycles design is more efficient in the use of spare capacity and requires much less spare capacity than the conventional pcycles design.

Integrated Effects of Phosphate Rock and Chemical Fertilizers on the Dynamics of Soil Bacterial in Acidic Rice Paddy Soils of Man (Ivory Coast)

In agricultural soils, phosphorus is often limited, leading farmers to employ artificial supplementation through both inorganic and organic fertilization methods due to its restricted availability. Soil fertilization has the potential to augment both the abundance and diversity of bacterial communities. Our study aimed to assess the effects of phosphate amendments, derived from natural phosphate rock, and chemical fertilizers (TSP, NPK), on the density and diversity of bacterial communities within the study plots. We developed and applied eight phosphate amendments during the initial cultivation cycle. Soil samples were collected post 1st and 2nd cultivation cycles, and the quantification of both total and cultivable phosphate-solubilizing bacteria (PSB) was conducted. Additionally, we analyzed bacterial community structure, α-diversity (Shannon Diversity Index, Evenness Index, Chao1 Index). The combination of natural phosphate rock (PR) and chemical fertilizers (TSP, NPK) significantly increased (p 7 bacteria/g dry soil) and phosphate-solubilizing bacteria (0.01 to 6.8 × 107 PSB/g dry soil) in comparison to unamended control soils. The diversity of bacterial phyla (Firmicutes, Actinobacteria, Proteobacteria, Halobacterota, Chloroflexia) observed under each treatment remained consistent regardless of the nature of the phosphate amendment applied. However, changes in the abundance of the bacterial phyla populations were observed as a function of the nature of the phosphate amendment or chemical fertilizer. It appears that the addition of excessive natural phosphate rock does not alter the number and the diversity of soil microorganisms population despite successive cultivation cycles. However, the addition of excessive chemical fertilizer reduces soil microorganisms density and structure after the 2nd cultivation cycle.

基于非简单的失效独立的路径保护圆的抗毁性光纤网络优化设计(英文)

提出了一个新的基于简单及非简单的失效独立的路径保护圆(FIPP p-cycles)的抗毁性光纤网络保护方法.从带宽利用率的角度比较研究了非简单及简单FIPP p-cycles.提出的新设计方法基于一种大规模优化工具,即列生成技术.与传统设计方法相比,新提出的基于列生成的方法在优化过程中动态生成候选的FIPP p-cycles,不要求预先枚举出任何候选者.实验结果显示与基于简单FIPP p-cycles抗毁性全光纤网络设计相比,基于非简单的FIPP p-cycles设计可非常有效的利用带宽.

WDM光网络双链路故障混合保护算法

针对WDM光网络中的双链路故障,采用P-cycle与共享通路保护结合的方式来实现。其主要思路是:对给定的工作路径,在寻找一条与工作通路分离的保护通路的同时,再为工作通路上的每条链路寻找与保护通路部分分离的P-cycle。最后在三种不同的业务模型下进行了仿真,结果显示该算法能实现双链路故障的100%恢复,并且具有较低的阻塞率和资源冗余度。

PTN网络安全结构的优化与设计

分组传送网(Packet Transport Network,PTN)能够兼容多种网络,诸如ATM、SDH、以太网、PDH、PPP/HDLC等,被广泛地应用到各种组网通信,PTN能够有机地结合数据技术和传输技术,使运营商的基础网络优势得到很大程度的提高。目前,分组传送网(PTN)在多网络通讯、传输带宽、流量、信息安全等方面无法满足用户需求,文中设计出新型的PTN网络安全架构,根据业务及流量选择架构类型,并引入融入OTN核心组网和p-Cycle保护算法,通过使用OTN核心组网方案,使汇聚机房带宽和数据传输能力大大提高,具有较强的扩容能力,通过使用p-Cycle保护算法并构建组网拓扑图,提高了PTN网络信息数据传递的安全性能。文中还设计出PTN组网软件架构,便于用户应用、查询。实验表明,设计的方案大大降低了组网难度,提高了网络速度、服务质量,具有较好的网络可扩展性和安全性。