An overview of p-cycle based optical multicast protection approaches in mesh WDM networks

This paper provides an overview of p-cycle based optical multicast protection approaches for link failure recovery, combined node and link failure recovery, and source failure recovery on top of combined node and link failure recovery. We discuss several recently proposed p-cycle based optical multicast protection approaches, including the link-protecting p-cycle based optical multicast protection approach, the tree-protecting p-cycle based optical multicast protection approach, node-and-link protecting p-cycle based optical multicast protection approach, and flow p-cycle based optical multicast protection approach. They outperform other existing optical multicast protection approaches in both capacity efficiency and recovery speed.     

光网络的保护恢复的研究

随着波分复用(WDM)技术的飞速发展,光网络的生存性要求也越来越高,文章阐述了光网络中通用的几种保护方法,给出了这几种保护方法的特点及使用范围,并且就资源利用率、造价、倒换时间、对节点的要求和对网络拓扑的要求这几方面做了比较和分析。最后得出在不同的网络,不同的生存性要求和不同的负载的情况下应采取不同的保护恢复方法。     

Automatic protection switching for p-cycles in WDM networks

p-Cycle recovery relies on a protection switching protocol. We detail several issues for such a protocol taking the evolution from ring networks to p-cycles into account. In particular, we propose and evaluate a protocol enhancement to provide means for node failure protection. For the evaluation, we describe an integer linear program, which is applied to network design case studies, and formulate availability models for p-cycles. The case studies show that the protocol enhancement improves availability at marginal additional design cost.     

Preplanned rerouting optimization and dynamic path rerouting for ATM VP restoration

The survivability for ATM based B‐ISDN has become an important challenge for telecommunication network planners and engineers. In this paper, we consider multiple grades of reliability concept and a multilayer survivable network architecture for survivable ATM networks. We address two complementary ATM VP restoration schemes in this paper. First, we propose preplanned rerouting models and algorithms based on combinatorial optimization to prepare efficient backup VP configuration. We test two formulations and algorithms for this problem. Efficient column generation technique to solve linear programming relaxation and strong valid inequalities incorporating the branch‐and‐bound scheme are suitable to solve the problem to optimality within small time limits. Second, we propose a new dynamic VP path restoration scheme to restore nonprotected VPs by the preplanned rerouting. Our protocol has shown the advantage in restoration effectiveness comparing a well‐known protocol in computational simulation. We, finally, address the relationships between the suggested models of this paper and the expected results of our ongoing project. This revised version was published online in August 2006 with corrections to the Cover Date.     

WDM光网络中一种优先共享通路保护算法

为了提高波分复用光网络的可靠性,常采用分段共享通路保护算法,该方法通常要求保护通路要均匀分段并且应满足共享风险链路组约束,网络业务的阻塞率也就比较高,因此提出了用优先共享通路保护算法来降低业务阻塞率。通过计算机仿真进行了理论分析和实验验证,取得了两种保护算法下的业务阻塞率和资源预留比的数据。结果表明,优先共享保护通路算法能够有效地融合分段共享通路保护算法的优点,同时在业务的阻塞率和资源预留比方面优于分段共享保护通路算法。     

用于Mesh光网络快速保护恢复的GMPLS信令机制的扩展

分析了Mesh光网络保护机制和恢复机制,并对GMPLS信令机制进行了扩展,给出了扩展后实现保护恢复的协议格式和信令流程,最后依据实验数据给出扩展的GMPLS信令机制的保护、恢复时间的仿真结果.     

A path inflation control strategy for dynamic traffic grooming in IP/MPLS over WDM network

The use of alternate routes for traffic grooming in IP/MPLS over wavelength-division multiplexing (WDM) networks may lead to the propagation of congestion from one link to others in the IP/MPLS layer. This can be tackled by using the path inflation control (PIC) strategy proposed here for operating an IP/MPLS over WDM network in the overlay model. This supports dynamic traffic grooming with less blocking than other strategies. Network resource usage is also efficient as new lightpaths are set up for a new label switched path (LSP) request only when indicated by the congestion conditions.     

Two new heuristic approaches for optimal path calculation on occupancy grid map

A broader industrial application of mobile intelligent robots fails, especially at small and medium enterprises, because of its high cost. Therefore, worldwide current research is focused on developing “affordable—Cost-oriented (COR)” robots. One contribution to this field of research is to find favorable methods for path planning and navigation. Therefore, in this paper two new methods are presented which can be realized with low-cost hardware and software. Amongst others, these heuristics methods, compared to previously known methods, provide the advantage of low computation time, however, with a small loss of accuracy, negligible for most applications.     

Multi-link failure restoration with dynamic load balancing in spectrum-elastic optical path networks

In this paper, we investigate network performance of multi-link failure restoration in spectrum-elastic optical path networks (SLICE). To efficiently restore traffic under multi-link failures, a novel survivable algorithm, named dynamic load balancing shared-path protection (DLBSPP), is proposed to compute primary and link-disjoint shared backup paths. The DLBSPP algorithm employs first fit (FF) and random fit (RF) schemes to search and assign the available spectrum resource. Traffic-aware restoration (TAR) mechanism is adopted in the DLBSPP algorithm to compute new routes for carrying the traffic affected by the multi-link failures and then the multi-link failures can be efficiently restored. Simulation results show that, compared with the conventional shared-path protection (SPP) algorithm, the DLBSPP algorithm achieves lower blocking probability (BP), better spectrum utilization ratio (SUR), more reasonable average hop (AH) and higher failure restoration ratio (FRR). Thus, the proposed DLBSPP algorithm has much higher spectrum efficiency and much better survivability than SPP algorithm.     

一种ASON网络中分级服务的实现与仿真

自动交换光网络(ASON)中具有灵活多样的生存性机制,根据业务对故障恢复的可靠性要求,可以为其提供适当的保护恢复机制.文章提出了一种在ASON中实现的分级服务方案,首先以恢复时间为标准定义出不同的生存性等级,然后给出了实现该方案的功能模块及流程图,最后对该方案进行了仿真分析.     

WDM光网络中一种新型的动态共享保护算法

波分复用(WDM)光网络中引入了共享风险链路组(SRLG)的概念 ,要求工作通路与保护通路不能处于同一个SRLG之中.文章提出了一种基于SRLG限制的动态共享通道保护算法,即满足K对业务的动态链路权重配置(K-Dynamic Link Weight Configuration, K-DLWC)算法 ,该算法的     

SDH传输网中的光电路路由算法

根据目前在SDH传输网管中存在的快速开通光路和电路的具体需求,针对由若干环构成的网络拓扑较为复杂的SDH传输网提出了光电路路由算法和电路路由算法,算法以光电路分层模型为基础进行,能迅速进行光路和电路的路由调度。最后对算法进行了简单的分析。     

A generic cognitive framework for supervising the radio dynamic reconfiguration

Cognitive radio is a technological concept pushing for the introduction of intelligent radio operation that goes beyond traditional system adaptation. So far, a rather limited amount of work has been published on the cognitive mechanisms that should be embedded into communicating equipments to achieve such an intelligent behavior. This paper presents a generic cognitive framework for autonomous decision making with regard to multiple, possibly conflicting, operational objectives in a time-varying environment. The framework is based on the definition of two scales introducing order relationships between the configurations that help the reasoning and learning processes. The resulting cognitive engine learns to progressively identify the optimal configurations for the design objectives imposed given the current radio environment. The proposed approach is illustrated for a case of cognitive waveform design and extensive simulation results validate the cognitive engine behavior.     

Protection approaches for dynamic traffic in IP/MPLS-over-WDM networks

Due to the explosive growth of data-related traffic driven by the Internet, network reliability becomes an important issue. We investigate various protection approaches to handle failures for dynamic traffic demands in IP/MPLS-over-WDM networks. An LSP can be protected at either the IP/MPLS layer or the optical layer. In IP/MPLS layer protection, an LSP is protected by providing a link-disjoint backup LSP between its end nodes. In optical layer protection, an LSP is protected by the backup lightpath of each lightpath traversed by the LSP. We present two integrated routing algorithms: hop-based integrated routing algorithm and bandwidth-based integrated routing algorithm (BIRA) to set up the restorable bandwidth-guaranteed paths efficiently. Then we present a multilayer protection scheme for multiclass traffic in such networks. This scheme takes into account the different QoS and recovery requirements of the traffic to provide protection capability either at the MPLS layer or at the optical layer in a cost-effective manner. We use the connection blocking probability and number of optical-electrical-optical conversions as performance metrics to compare various protection approaches.     

WSNs中优化移动信宿路径的数据收集算法

收集数据是部署无线传感网络(WSNs)的根本目的。采用移动信宿策略可有效缓解WSNs的能耗问题,信宿的移动路径是该策略的关键。为此,提出基于伪驻留点的数据收集(VRDC)算法。VRDC算法先依据驻留点规划信宿路径,再依据路径选择伪驻留点(VRPs)。VRPs可通过一跳直接向移动信宿传输数据,而其他的节点则将数据传输至最近的VRPs,进而减少传输跳数,降低能耗。仿真结果表明,提出的VRDC算法能有效降低能耗,并平衡节点间的能耗。     

Partial SRLG-disjoint shared path protection with differentiated reliability in survivable WDM network

This paper addresses the problem of shared path protection algorithm in survivable wavelength-division-multiplexing (WDM) optical networks, taking into consideration of differentiated reliability (DiR) under Shared-Risk-Link-Group (SRLG) constraint. A subset of network links that share the risk of failure at the same time are said to be in a common SRLG. Rather than the conventional complete SRLG-disjoint shared path protection, we introduce a heuristic Partial SRLG-disjoint Shared Path Protection algorithm (Pd-SPP) based on the concept of SRLG conditional failure probability, to provide differentiated reliability protection. The main target of our work is to improve the network resource utilization ratio under the DiR constraint. We adopt the ideas of partial SRLG-disjoint and the K-shortest paths algorithm such we can efficiently solve the “trap” problem. The experimental results show that our algorithm outperforms the complete SRLG-disjoint shared path protection in both blocking probability ratio and network resource utilization, i.e. the results are found to be promising.     

面向智能电网的继电保护系统重构研究

在本文中以智能电网为基础,对智能电网建设中继电保护系统的重构进行研究.     

Embedding and reconfiguration algorithms for service aggregation in network virtualization

Network virtualization and transmission quality optimization are promising techniques for future Internet. Previous researches on virtual network embedding focused on efficient utilization of network resources. In this paper, we present a virtual network embedding scheme that aims at improving the effect of transmission quality optimization. In order to enable more service benefit from optimization, the embedding algorithm presented in this paper follows the service aggregation embedding principle. We also develop a reconfiguration algorithm based on service aggregation and load balance. Simulation experiments demonstrate that the proposed algorithms can achieve good performance on service aggregation as well as efficient resource utilization. Copyright © 2014 John Wiley & Sons, Ltd.     

Access network survivability: an architecture approach for monitoring, protection and restoration in FTTH application

This paper presented a simple monitoring, protection switching, and fast restoration approach for fiber to the home passive optical network (FTTH-PON) using Access Control System (ACS). ACS is developed for centralized monitoring and failure detection from central office (CO) in downstream direction (from CO towards customer sides). The proposed system architecture incorporating low cost and enable the network service providers and field engineers to remotely control the testing module from anywhere in the world and automatically identify any fiber fault and address the failure location in the fiber field. Another unique function of ACS is to provide the activation for optical switching in a restoration scheme which implemented at the drop region of FTTH-PON. A protection device named Customer Protection Device that comprises of programmable optical switches will be employed at the customer sides, just before the optical network unit, for rerouting the disrupted signals to the protection line when failure occurs in the working line to ensure continuous service delivery to customers.     

GMPLS的一种镜像保护恢复机制

对通用多协标记交换(GMPLS)在控制平面的保护恢复技术作了系统的分析和研究;引进了一种对链路信息进行备份恢复的镜像恢复机制,并对此机制进行了分析,提出了改进方案,有效地解决了"多余备份"的现象.