Management,control, and design of integrated networks with real-time dynamic routing

Integrated real-time dynamic routing (IRR) networks provide dynamic routing features for multiple classes-of-service on an integrated transport network. In this paper it is shown that IRR networks allow reduced network management costs since with real-time dynamic routing a number of network operations are simplified or eliminated. These simplifications include eliminating the storage of voluminous routing tables in the network switches, eliminating the calculation of routing tables in network design, simplifying the routing administration operations which require downloading new routing information to the network, and eliminating the automatic rerouting function in on-line traffic management. A new bandwidth allocation technique is described here which is based on the optimal solution of a network bandwidth allocation model for IRR networks. The model achieves significant improvement in both the average network blocking and node pair blocking distribution when the network is in a congested state such as under peak-day loads. In a paper to appear in the next Journal issue we further describe a new algorithm for the transport design of IRR networks which achieves near-optimal capacity engineering. These optimization techniques attain significant capital cost reductions and network performance improvements by properly modeling the more efficient operation of IRR networks.     

A dynamic fault-tolerant message routing algorithm for double-loop networks

Message routing is a fundamental function of a network, and fault-tolerance is an important tool to ensure the quality of service of a network. Assume that the network contains at most one faulty element and the algorithm does not know the faulty element in advance. We present an optimal fault-tolerant message routing algorithm for double-loop networks. We show that sending at most two messages with different routing strategies can ensure that one of the messages will be sent through a shortest path that avoids the faulty element. At each vertex, for any destination, the algorithm needs only constant time and space to determine the next vertex to which the message is to be sent.     

计算机网络互连的路由算法的设计及仿真研究

互连网络目前应用最广泛、最流行的一种网络拓扑,广泛应用于多处理器系统、电话网络、分布式计算机系统及路由器交换机等领域。本文主要对直连网络的负载均衡路由算法进行了研究,提出了一种新的负载均衡路由算法。通过对该算法的仿真发现在相同的网络仿真环境下,该算法的性能要优于传统路由算法。     

A memetic approach to vehicle routing problem with dynamic requests

The paper presents an effective algorithm for solving Vehicle Routing Problem with Dynamic Requests based on memetic algorithms. The proposed method is applied to a widely-used set of 21 benchmark problems yielding 14 new best-know results when using the same numbers of fitness function evaluations as the comparative methods. Apart from encouraging numerical outcomes, the main contribution of the paper is investigation into the importance of the so-called starting delay parameter, whose appropriate selection has a crucial impact on the quality of results. Another key factor in accomplishing high quality results is attributed to the proposed effective mechanism of knowledge transfer between partial solutions developed in consecutive time slices. While particular problem encoding and memetic local optimization scheme were already presented in the literature, the novelty of this work lies in their innovative combination into one synergetic system as well as their application to a different problem than in the original works.     

A cross-layer optimization based integrated routing and grooming algorithm for green multi-granularity transport networks

With the development of IP networks and intelligent optical switch networks, the backbone network tends to be a multi-granularity transport one. In a multi-granularity transport network (MTN), due to the rapid growth of various applications, the scale and complexity of network devices are significantly enhanced. Meanwhile, to deal with bursty IP traffic, the network devices need to provide continuous services along with excessive power consumption. It has attracted wide attention from both academic and industrial communities to build a power-efficient MTN. In this paper, we design an effective node structure for MTN. Considering the power savings on both IP and optical transport layers, we propose a mathematical model to achieve a cross-layer optimization objective for power-efficient MTN. Since this optimization problem is NP-hard (Hasan et al. (2010)  [11]) and heuristic or intelligent optimization algorithms have been successfully applied to solve such kinds of problems in many engineering domains (Huang et al. (2011)  [13], Li et al. (2011)  [17] and Dong et al. (2011)  [5]), a G  reen integrated R$R$outing and Grooming algorithm based on Biogeography-Based Optimization (Simon (2008)  [23]) (GRG_BBO) is also presented. The simulation results demonstrate that, compared with the other BBO based and state-of-the-art power saving approaches, GRG_BBO improves the power savings at a rate between 2%–15% whilst the high-level multi-user QoS (Quality of Services) satisfaction degree (MQSD) is guaranteed. GRG_BBO is therefore an effective technique to build a power-efficient MTN.     

A fault-tolerant routing scheme in dynamic networks

In dynamic networks,links and nodes will be deleted or added regularly.It is very essential for the routing scheme to have the ability of fault-tolerance.The method to achieve such a goal is to generate ore than one path for a given set of source and destination.In this paper,the idea of inderval routing is used to construct a new scheme(Multi-Node Label Interval Routing Scheme,or MNILIR scheme)to realizee fault-tolerance.Interval routing is a space-efficinet routing method for netwroks ,but the method is static and determinative,and it cannot realize faulttoloerance.In MNLIR scheme some nodes will have more than one label,thus some parirs of destination and source will have more than one path;the pairs of nodes, which have inheritance relation,will have the shortest path.Using this character,MNLIR scheme has better overall routing performance than the former interval routing scheme,which can be proven by simulations.The common problem concerning the insertion and deletion of nodes and links is considered in this paper.So if the networks have some changes in topology,MNLIR scheme may find alternative path for certain paris of nodes.In this way,fault-tolerance can be realized with only a little space added to store the multi-node labels.     

Permutation routing in double-loop networks: design and empirical evaluation

A double-loop network is an undirected graph whose nodes are integers 0,1,…,n−1 and each node u is adjacent to four nodes u±h₁(mod>n), u±h₂(mod>n), where 0<h₁<h₂<n/2. There are initially n packets, one at each of the n nodes. The packet at node u is destined to node π(u), where the mapping uπ(u) is a permutation. The aim is to minimize the number of routing steps to route all the packets to their destinations. If ℓ is the tight lower bound for this number, then the best known permutation routing algorithm takes, on average, 1.98ℓ routing steps (and 2ℓ routing steps in the worst-case).Because the worst-case complexity cannot be improved, we design four new static permutation routing algorithms with gradually improved average-case performances, which are 1.37ℓ, 1.35ℓ, 1.18ℓ, and 1.12ℓ. Thus, the best of these algorithms exceeds the optimal routing by at most 12% on average.To support our algorithm design we develop a program which simulates permutation routing in a network according to the given topology, routing model as well as communication pattern and measure several quality criteria. We have tested our algorithms on a large number of double-loop networks and permutations (randomly generated and standard).     

Complexity and design of QoS routing algorithms in wireless mesh networks

Quality of service (QoS) provisioning in wireless mesh networks (WMNs) is an open issue to support emerging multimedia services. In this paper, we study the problem of QoS provisioning in terms of end-to-end bandwidth allocation in WMNs. It is challenging due to interferences in the networks. We consider widely used interference models and show that except a few special cases, the problem of finding a feasible path is NP-complete under the models. We propose a k-shortest path based algorithmic framework to solve this problem. We also consider the problem of optimizing network performance by on-line dynamic routing, and adapt commonly used conventional QoS routing metrics to be used in WMNs. We find the optimal solutions for these problems through formulating them as optimization models. A model is developed to check the existence of a feasible path and another to find the optimal path for a demand; moreover, an on-line optimal QoS routing algorithm is developed. Comparing the algorithms implemented by the proposed framework with the optimization models shows that our solution can find existing feasible paths with high probability, efficiently optimizes path lengths, and has a comparable performance to the optimal QoS routing algorithm. Furthermore, our results show that contrary to wireline networks, minimizing resource consumption should be preferred over load distribution even in lightly loaded WMNs.     

具有高效确认机制的双层卫星网络多径路由协议

针对资源受限的LEO卫星网络中传统单路径路由协议数据传输速率较低的问题,基于GEO/LEO双层卫星网络模型提出一种基于网络编码（NC）的双层卫星网络多径路由协议（N-NCMR）。首先,通过GEO卫星为LEO卫星网络计算路由减轻LEO卫星的负担,结合NC技术动态地沿着多个不相交路径传输数据流的不同部分;其次,设计了一种高效的延迟确认机制加速数据传输,源节点在接收到前一组的确认（ACK）消息之前可以连续发送后续的组。仿真结果表明,该路由协议显著提高了LEO卫星网络的吞吐量和数据传输效率。     

基三分层互连网络及其路由算法设计

从降低节点度、减少网络链路数和缩短网络直径的角度出发,提出一种新型的互连网络结构--基三分层互连网络,深入地研究了该网络的静态度量并和2-D Mesh做了相应的比较.针对基三分层互连网络提出了一种使消息沿两节点间确定路径传递的分布式确定路由算法DDRA.该算法充分利用基三分层互连网络的层次特性,不需要构建路由表,且算法实现简单,路由效率高,且易于硬件实现.     

Supply chain network design using an integrated neuro-fuzzy and MILP approach: A comparative design study

In this study, an integrated supply chain (SC) design model is developed and a SC network design case is examined for a reputable multinational company in alcohol free beverage sector. Here, a three echelon SC network is considered under demand uncertainty and the proposed integrated neuro-fuzzy and mixed integer linear programming (MILP) approach is applied to this network to realize the design effectively. Matlab 7.0 is used for neuro-fuzzy demand forecasting and, the MILP model is solved using Lingo 10.0. Then Matlab 7.0 is used for artificial neural network (ANN) simulation to supply a comparative study and to show the applicability and efficiency of ANN simulation for this type of problem. By evaluating the output data, the SC network for this case is designed, and the optimal product flow between the factories, warehouses and distributors are calculated. Also it is proved that the ANN simulation can be used instead of analytical computations because of ensuring a simplified representation for this method and time saving.     

动态传感器网络移动代理路由算法

提出一种基于蚁群优化的动态传感器网络移动代理能量有效路由算法.该算法设计了一种新的路径选择概率模型,使移动代理能找到一条从处理节点到目标节点之间的能量有效路径,该路径兼顾了路径能量消耗和节点剩余能量情况;该算法还制定了新的蚁群局部信息素再初始化规则,该规则在网络中发生动态变化的节点附近进行局部信息素再初始化,快速有效地更新最优路径.与其他算法相比,该算法能找到一条能量消耗较小,并且节点剩余能量较多的有效路径.     

An integrated planning tool for design of recycled water distribution networks

Pipeline design of urban recycled water networks involves thousands of decisions to ensure delivery of water to multiple use locations with pipelines and pump stations correctly located, optimally sized, and compatible with existing infrastructure. Here, we introduce PRODOT, Pipeline ROuting and Design Optimization Tool, software that identifies near-minimum-cost pipeline routes; accounts for existing configurations, legal, environmental or safety concerns, and trade-offs in pipeline length, pipe installation methods, traffic congestion during construction; optimizes pump station locations, pumping energy, pipe diameters and pressure classes; and includes theoretical additional capacity of each pipe, facilitating future expansion. We illustrate the utility of PRODOT with a case study for a local utility comparing PRODOT-generated configurations to a configuration proposed by an experienced consulting firm. The comparison shows that PRODOT produces pipeline configurations similar to the consulting firm's proposal with improvements by effectively and more broadly incorporating options the consultant may not have considered.     

能量均衡的动态间隔分层路由协议*

针对无线传感器网络中分簇多跳通信方式产生的能量负载不均衡问题,提出一种能量均衡的动态间隔分层路由协议（EHRD）。它通过层次间隔动态调整算法动态调整层次间隔,使得层次的能量消耗不均匀状况得到缓解,从而达到整个网络能量负载均衡。用NS2仿真测试结果显示：能量均衡的动态间隔分层路由协议在网络能量负载、网络生存时间、缓解网络“热区”问题上有所提高。     

Dynamic shortest path problems: Hybrid routing policies considering network disruptions

Traffic network disruptions lead to significant increases in transportation costs. We consider networks in which a number of links are vulnerable to these disruptions leading to a significantly higher travel time on these links. For these vulnerable links, we consider known link disruption probabilities and knowledge of transition probabilities for recovering from or getting into a disruption. We develop a framework based on dynamic programming in which we formulate and evaluate different known online and offline routing policies. Next to this, we develop computation-time-efficient hybrid routing policies. To test the efficiency of the different routing policies, we develop a test bed of networks based on a number of characteristics and analyze the results in terms of routes, cost performance and calculation times. Our results show that a significant part of the cost reduction can be obtained by considering only a limited part of the network in detail. The performance of our proposed hybrid policy is only slightly worse than the optimal policy.     

The dynamic multiperiod vehicle routing problem with probabilistic information

This paper introduces the Dynamic Multiperiod Vehicle Routing Problem with Probabilistic Information, an extension of the Dynamic Multiperiod Vehicle Routing Problem in which, at each time period, the set of customers requiring a service in later time periods is unknown, but its probability distribution is available. Requests for service must be satisfied within a given time window that comprises several time periods of the planning horizon. We propose an adaptive service policy that aims at estimating the best time period to serve each request within its associated time window in order to reduce distribution costs. The effectiveness of this policy is compared with that of two alternative basic policies through a series of computational experiments.     

两层复杂网络上的动态权重路由策略研究

为了提高两层复杂网络处理数据包的网络容量,提出了一种基于队列长度的路由策略,称之为动态权重路由策略,即逻辑层链路的权重与其映射的物理层节点队列长度有关,并按照队列长度的变化,动态地更新链路权重,然后数据包按照权重最小路径路由。仿真结果表明,与传统的最短路径路由策略和静态的全局意识路由策略相比,动态权重路由策略可以进一步地增强两层复杂网络的网络容量。     

IP Mesh网络的多约束QoS选路研究

多约束QoS路由算法一直是研究重点和难点,是一个有待解决的NP完全问题。针对IP Mesh网络的特点,设计出相应的完全图,并且推出了n个节点的完全图路径总数目公式。提出了一种CBFS_MCP算法,首先用Dijsktra最短路径算法对节点和边进行删减,将完全图简化,再在简化图上用类BFS算法通过“约束条件夹逼”和不断剪枝,寻找一条从起点s到终点t的符合两个约束条件的可行路径。实验结果表明CBFS_MCP算法有着良好的算法性能。     

The robust vehicle routing problem with time windows

This paper addresses the robust vehicle routing problem with time windows. We are motivated by a problem that arises in maritime transportation where delays are frequent and should be taken into account. Our model only allows routes that are feasible for all values of the travel times in a predetermined uncertainty polytope, which yields a robust optimization problem. We propose two new formulations for the robust problem, each based on a different robust approach. The first formulation extends the well-known resource inequalities formulation by employing adjustable robust optimization. We propose two techniques, which, using the structure of the problem, allow to reduce significantly the number of extreme points of the uncertainty polytope. The second formulation generalizes a path inequalities formulation to the uncertain context. The uncertainty appears implicitly in this formulation, so that we develop a new cutting plane technique for robust combinatorial optimization problems with complicated constraints. In particular, efficient separation procedures are discussed. We compare the two formulations on a test bed composed of maritime transportation instances. These results show that the solution times are similar for both formulations while being significantly faster than the solutions times of a layered formulation recently proposed for the problem.     

基于效用的容迟网络路由技术研究*

容迟网络作为移动自组网和传感器网络最新的发展形式,在智能公路、生物监测、卫星通信、乡村通信、个人信息交换等领域具有十分广阔的应用前景。容迟网络路由设计是一个富有挑战性和前景的新兴研究领域,本文概述了容迟网络路由技术的发展、面临的挑战和评价指标,对容迟网络路由协议进行了分类,详细介绍了目前主要基于效用的路由协议基本原理和特点,并进行深入分析和比较,最后结合该领域当前研究现状,对未来研究容迟网络效用路由算法进行了总结和展望。