Managing the network manager

A network management and control simulator (NEMACS) software testbed for developing, testing, and integrating different network management (NM) techniques for multiservice circuit-switched networks is discussed. NEMACS is capable of applying different NM strategies to a plethora of simulated network scenarios that include networks of differing size, speed, transport topology, control, and management architectures. NEMACS simulates networks by modeling the behavior of various network modules: call transport modules (CTMs), call control modules (CCMs), and network control modules (NCMs). The implementation of NEMACS software and four examples of how NEMACS has been used to rapidly prototype NM techniques are presented. The examples deal with focused overload in a simple network, predictive access-control and routing strategy, decentralized management, and multiclass traffic control     

基于机器学习的光网络路由与频谱分配机制研究

对于光网络而言,路由与频谱分配是制约光层资源利用率和光网络容量的重要问题之一.机器学习迅速发展,为光网络管理与控制的智能化、自动化提供了新的发展方向.本文回顾了近年来基于机器学习的路由频谱分配相关研究,介绍了光网络控制中常见的机器学习算法,描述了基于神经网络和强化学习的路由频谱分配机制,最后分析了当前研究在泛化性和可靠...     

Effective bandwidth-based admission control for multiservice CDMAcellular networks

We develop product form traffic models for single- and multiple-cell code-division multiple-access (CDMA) networks with multiple classes of mobile subscribers. The key feature of this development is the specification of a flexible call admission control procedure that details the numbers of mobiles of each class in each cell that the system operator should allow in order to maintain an acceptable quality of service. Effective bandwidth techniques from the analysis of statistical multiplexing at an asynchronous transfer mode (ATM) based broadband integrated services digital network (ISDN) link are used to give performance guarantees that overcome the variability in interference levels characteristic of CDMA cellular networks. The result is an admissible region bounded by a finite number of hyperplanes and a simple and efficient call admission policy. The CDMA mobile network, operating within the admissible region described, has a very similar form to a circuit-switched network operating with fixed routing. This similarity allows the existing traffic modeling techniques and network management strategies for general loss networks to be applied to CDMA mobile cellular networks. In particular, with standard assumptions on the call arrival processes and holding times, the stationary state distribution has a product form on the truncated state space defined by the call admission strategy     

Achieving network optima using Stackelberg routing strategies

In noncooperative networks users make control decisions that optimize their individual performance objectives. Nash equilibria characterize the operating points of such networks. Nash equilibria are generically inefficient and exhibit suboptimal network performance. Focusing on routing, a methodology is devised for overcoming this deficiency, through the intervention of the network manager. The manager controls part of the network flow, is aware of the noncooperative behavior of the users and performs its routing aiming at improving the overall system performance. The existence of maximally efficient strategies for the manager, i.e., strategies that drive the system into the global network optimum, is investigated. A maximally efficient strategy of the manager not only optimizes the overall performance of the network, but also induces an operating point that is efficient with respect to the performance of the individual users (Pareto efficiency). Necessary and sufficient conditions for the existence of a maximally efficient strategy are derived, and it is shown that they are met in many cases of practical interest. The maximally efficient strategy is shown to be unique and it is specified explicitly     

A Review on Hierarchical Routing Protocols for Wireless Sensor Networks

The routing protocol for Wireless Sensor Networks (WSNs) is defined as the manner of data dissemination from the network field (source) to the base station (destination). Based on the network topology, there are two types of routing protocols in WSNs, they are namely flat routing protocols and hierarchical routing protocols. Hierarchical routing protocols (HRPs) are more energy efficient and scalable compared to flat routing protocols. This paper discusses how topology management and network application influence the performance of cluster-based and chain-based hierarchical networks. It reviews the basic features of sensor connectivity issues such as power control in topology set-up, sleep/idle pairing and data transmission control that are used in five common HRPs, and it also examines their impact on the protocol performance. A good picture of their respective performances give an indication how network applications, i.e whether reactive or proactive, and topology management i.e. whether centralized or distributed would determine the network performance. Finally, from the ensuring discussion, it is shown that the chain-based HRPs guarantee a longer network lifetime compared to cluster-based HRPs by three to five times.     

A distributed control strategy for wireless ATM networks

Cellular networks are expected to be upgraded to offer Personal Communication Services (PCS). The mobility management and wireless call control approach used in cellular networks are currently being proposed for use in PCS networks. Recent work indicates that both the signaling load and database update rates caused by these mobility management and call control procedures will increase significantly in next generation PCS networks. In this paper, we propose and analyze a new cluster-based architecture and define algorithms to effectively handle mobility management and call control functions for PCS. We assume an ATM network infrastructure. Some of the key aspects of our proposal include simplifying the mobile location and tracking function, performing connection setup in segments, eliminating the need for user service profile downloads between networks, and more efficient routing of connections by removing the need for an anchor switch. Advantages of this approach include a reduction in signaling traffic load, improved call/connection setup delays, and more efficient routing of connections. We carry out an analysis of our solution for high-tier PCS applications.     

Cross-Layer Optimization of MAC and Network Coding in Wireless Queueing Tandem Networks

In wireless networks, throughput optimization is an essential performance objective that cannot be adequately characterized by a single criterion (such as the minimum transmitted or sum-delivered throughput) and should be specified over all source-destination pairs as a rate region. For a simple and yet fundamental model of tandem networks, a cross-layer optimization framework is formulated to derive the maximum throughput region for saturated multicast traffic. The contents of network flows are specified through network coding (or plain routing) in network layer and the throughput rates are jointly optimized in medium access control layer over fixed set of conflict-free transmission schedules (or optimized over transmission probabilities in random access). If the network model incorporates bursty sources and allows packet queues to empty, the objective is to specify the stability region as the set of maximum throughput rates that can be sustained with finite packet delay. Dynamic queue management strategies are used to expand the stability region toward the maximum throughput region. Network coding improves throughput rates over plain routing and achieves the largest gains for broadcast communication and intermediate network sizes. Throughput optimization imposes fundamental tradeoffs with transmission and processing energy costs such that the throughput-optimal operation is not necessarily energy efficient.     

复杂网络与可扩展路由

互联网规模扩大,相应路由表大小呈指数增加,形成下一代互联网可扩展路由“瓶颈”。基于复杂网络和可扩展路由的相关理论与主要策略,文章对相关研究成果。如小世界效应所表现出来的特性、小世界和无标度网络模型,网格、层次及隐藏度量等3种可扩展路由网络模型,随机游走、贪婪、最大度、优先、本地介数、距离与度及相似性与度混合等多种路由策略等进行了分析与归纳。这些研究结果和方法为因互联网规模不断扩大所带来的路由系统可扩展性问题提供解决方案     

Density Based Fuzzy C Means Clustering to prolong Network Lifetime in Smart Grids

Wireless sensor networks (WSN's) are preferred for industrial applications due to progressive increase of sensor electronics. One such application is deployment of WSN's in smart grids. Smart Grid integrates information and communication techniques with electricity network. Smart grids utilize sophisticated control and monitoring devices for improving the efficiency of the grid. For energy efficient, low cost monitoring and control in smart grid WSN's is treated as a promising technology. Advanced Metering Infrastructure (AMI) is the key technology in the distribution networks of Smart Grid. The AMI is composed of various sensors for metering purpose. The meter data is also useful for the distribution operators to manage the demand response. The network involves smart meters, smart electric gas and water meters along with digital network management appliances for optimizing the electric network with real time data management. The smart sensors are limited in terms of battery, operational power and memory. These sensors communicate with the base station in restricted range. The communication between smart grid nodes and base station (sink) is multi-hop in nature. The communication takes place within limited range of communication so the security concerns that are involved in the network are to be handled by the routing protocols. So as to make the bidirectional communication efficient between the smart sensors and utility an effective routing scheme is required for these energy limited devices to handle the heavy network traffic in smart grids. Here energy efficient routing for WSN's in NAN networks to attain load balancing is proposed through density based Fuzzy C means clustering (DFCM). The obtained simulation results show that DFCM can provide a satisfactory performance for enhancing the network life span.

     

Comparison of Routing Procedures for Circuit-Switched Traffic in Nonhierarchical Networks

In this paper, we compare the use of different types of routing procedures for circuit-switched traffic in nonhierarchical networks. The main performance criterion used is the end-to-end blocking probability. The results show that if the network traffic is light, alternate routing performs better than nonalternate routing, but if the network traffic is heavy, the situation is reversed. To improve the performance of networks using alternate routing, different types of strategies varying from fixed control to dynamic control are introduced. A comparison based on numerical examples shows the improvement in performance attained by using a dynamic control strategy compared to fixed control. Good control techniques result in nonalternate routing under heavy traffic loads; nonalternate routing is the most viable alternative in nonhierarchical networks under heavy traffic conditions.     

A Cross-Layer Optimization Framework for Multihop Multicast in Wireless Mesh Networks

The optimal and distributed provisioning of high throughput in mesh networks is known as a fundamental but hard problem. The situation is exacerbated in a wireless setting due to the interference among local wireless transmissions. In this paper, we propose a cross-layer optimization framework for throughput maximization in wireless mesh networks, in which the data routing problem and the wireless medium contention problem are jointly optimized for multihop multicast. We show that the throughput maximization problem can be decomposed into two subproblems: a data routing subproblem at the network layer, and a power control subproblem at the physical layer with a set of Lagrangian dual variables coordinating interlayer coupling. Various effective solutions are discussed for each subproblem. We emphasize the network coding technique for multicast routing and a game theoretic method for interference management, for which efficient and distributed solutions are derived and illustrated. Finally, we show that the proposed framework can be extended to take into account physical-layer wireless multicast in mesh networks     

Optimized priority based energy efficient routing algorithm for mobile ad hoc networks

Recently more and more research interest focuses on the energy efficient routing in mobile ad hoc networks and many related routing algorithms are reported. In this paper, a new optimized priority based energy efficient routing algorithm is presented and priority is added to the existing routing algorithm according to the residual energy proportion of the nodes. Lower residual energy means lower priority and the nodes with lower priority are less likely to forward packets to other nodes. The algorithm needs no global information of the networks and only a little modification is needed to the existing algorithm, so it is practical to be implemented. The algorithm can improve the performance of routing discovery, routing maintenance and cache management at the same time. Some optimization strategy is taken to reduce the network overhead and the lifetime of the network is much longer and the network with our algorithm can transfer much more effective data. Simulation with NS-2 is done and satisfying results are obtained with this algorithm. The results show that the algorithm is efficient.     

Connectability: a performance metric for reconfigurable transportnetworks

This paper presents a metric for managing dynamically reconfigurable transport networks. In such networks, one physical set of transport links can be configured into many different logical networks, in order to meet uncertain and volatile traffic demands. Connectability is a figure of merit for capturing the composite routing efficiency and capacity utilization of a transport network. Connectability is mathematically inspired by existing metrics for reliability. Reliability concepts are adapted to quantify notions of efficiency in reconfigurable networks. The authors define connectability mathematically, and set out a procedure for its' calculation in a distributed real-time setting. The centralized version of this calculation has O(n log n) time complexity. A series of simulation studies are presented to illustrate the use of connectability in characterizing strategies for transport network reconfiguration. One strategy based on the isolated calculation of connectability at each node is shown to yield lower blocking and more efficient use of transport network resources than the other strategies tested. Finally, a short study of applying connectability to restoration in a national network demonstrates that there is a continuum along which restoration can be temporarily traded off against transport network management     

Strategies Towords Next Generation IP Over Optical Networks

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卫星网络路由技术现状及展望

与地面固定通信网络不同,卫星网络的节点高度动态性、有限的星上处理能力和网络拓扑周期性变化的特点给卫星互联网的路由协议与算法设计带来了新的挑战。该文系统梳理了学术界针对卫星网络所提出的路由技术,提出了卫星路由技术未来的发展方向。首先介绍了卫星网络架构和目前在卫星通信系统上应用的主要路由协议,并且简要介绍了卫星光通信网络的路由问题;其次,根据卫星节点的管理方式以及路由表生成方式将路由算法分类为集中式卫星路由、分布式卫星路由以及混合式卫星路由,详细介绍了各类卫星路由方法的代表性成果并总结其优化目标和适用场景;接着,总结了不同卫星网络场景和网络需求下如何选择合适的卫星路由算法;最后,阐述目前卫星路由技术面临的挑战以及未来的发展趋势,并在附录中介绍了当前主流的卫星网络仿真平台。     

Power‐efficient routing for SDN with discrete link rates and size‐limited flow tables: A tree‐based particle swarm optimization approach

Software‐defined networking is a promising networking paradigm for achieving programmability and centralized control in communication networks. These features simplify network management and enable innovation in network applications and services such as routing, virtual machine migration, load balancing, security, access control, and traffic engineering. The routing application can be optimized for power efficiency by routing flows and coalescing them such that the least number of links is activated with the lowest link rates. However, in practice, flow coalescing can generally overflow the flow tables, which are implemented in a size‐limited and power‐hungry ternary content addressable memory (TCAM). In this paper, a set of practical constraints is imposed to the software‐defined networking routing problem, namely, size‐limited flow table and discrete link rate constraints, to ensure applicability in real networks. Because the problem is NP‐hard and difficult to approximate, a low‐complexity particle swarm optimization–based and power‐efficient routing (PSOPR) heuristic is proposed. Performance evaluation results revealed that PSOPR achieves more than 90% of the optimal network power consumption while requiring only 0.0045% to 0.9% of the optimal computation time in real‐network topologies. In addition, PSOPR generates shorter routes than the optimal routes generated by CPLEX.     

A framework for inter-domain routing in virtual coordinate based mobile networks

Routing is considered to be one the most challenging problems in mobile ad hoc networks. It has been shown that the use of virtual coordinates or identifiers for efficient routing and data management has several advantages compared to classical topology control techniques based on pre-defined addresses or geographical coordinates. However, these advantages only hold for single domain networks with limited mobility. In a previous paper, we discussed the challenges arising from using virtual coordinates for routing (to a particular destination ID or to indexed data or resources) in mobile networks in multi-domain network scenarios. We developed a solution by managing data with a distributed hash table scheme. Based on our virtual cord protocol, we then implemented inter-domain routing using appropriate indirections. That approach, however, was still limited in finding efficient routes over multiple transit networks. In this paper, we extend that work by defining a framework for optimized inter-domain routing. In particular, we investigate the use of ant colony optimization for optimizing routes between multiple network domains. We show how distributed routing tables can be created and maintained and we outline a heuristic for finding candidate routes. Simulation experiments confirm the efficiency of the selected routes both on a intra and on a inter-domain level.     

A management and visualization framework for reconfigurable WDM optical networks

As the phenomenal advance in optical WDM networking technologies continues, optical WDM network equipment has been deployed not only in backbone networks, but also in regional, metropolitan, and access networks. It is widely believed that a major component of the next-generation Internet will be an IP-based optical network employing WDM. WDM wavelength routing and signaling have become an active research field, and dynamic and adaptive wavelength routing and assignment algorithms have been proposed. However, there is less work on reporting network control and management system implementation efforts over testbed WDM networks. This article presents a network management and visualization framework aimed at guiding the development of management applications for reconfigurable WDM optical networks. A layered framework architecture including element and network management and visualization is provided, and an object-based information model representing the WDM network is introduced. Functional components on reconfiguration, software agent, and network visualization services are presented, and important issues related to optical lightpath generation are discussed. A network visualization service also provides WDM control and management APIs to applications and access networks such as an IP network management system. To illustrate the usage of the framework, we share our experience in implementing the MONET network control and management system, and present network visualization views obtained from the MONET WDM network to highlight the framework features.     

Satellite constellation of MEO and IGSO network routing with dynamic grouping

Because inter‐satellite links (ISLs) among the distributed satellite nodes can be used to support autonomous control in satellite system operation to reduce dependency on the ground stations, it becomes a popular communication paradigm for the future satellite systems. However, this introduces great technical challenges, particularly for routing protocol to support such space communication system. Facing the challenges, we present out study of routing technology in this paper tailored for satellite network of MEO (Table 1) and IGSO with ISLs in addition to satellite–ground links. The study aims to explore the routing strategies and algorithms of satellite network based on the evolution law of network topology to provide reference design for data exchange in autonomous satellite system. A comprehensive investigation, ranging from the analysis of relevant factors affecting data exchange in satellite networks to the primary application and resource constraints in designing satellite routing strategy, has been conducted. Our main contribution is to propose an on‐demand computing and caching centralized routing strategy and algorithm on the satellite network. The routing strategy and algorithm is designed for satellite network topology dynamic grouping. The route calculation for user data transmission is divided into three phases: direction estimation, direction enhancement, and congestion avoidance. The strategy and algorithm provide significant advantages of high efficiency, low complexity, and flexible configuration, by which the satellite networks can provide the features of flexible configure, efficient transferring, easy management, structural survivability, and great potential in scalability. Copyright © 2013 John Wiley & Sons, Ltd.