Policy refinement for IP differentiated services Quality of Service management

Policy-based management provides the ability to dynamically re-configure DiffServ networks such that desired Quality of Service (QoS) goals are achieved. This includes network provisioning decisions, performing admission control, and adapting bandwidth allocation dynamically. QoS management aims to satisfy the Service Level Agreements (SLAs) contracted by the provider and therefore QoS policies are derived from SLA specifications and the provider's business goals. This policy refinement is usually performed manually with no means of verifying that the policies written are supported by the network devices and actually achieve the desired QoS goals. Tool support is lacking and policy refinement has rarely been addressed in the literature. This paper extends our previous approach to policy refinement and shows how to apply it to the domain of DiffServ QoS management. We make use of goal elaboration and abductive reasoning to derive strategies that will achieve a given high-level goal. By combining these strategies with events and constraints, we show how policies can be refined, and what tool support can be provided for the refinement process using examples from the QoS management domain. The approach presented here can be used in other application domains such as storage area networks or security management.     

ASAR: An ant-based service-aware routing algorithm for multimedia sensor networks

Aimed at three basic services (event-driven, data query and stream query), the paper presents a QoS routing model for multimedia sensor networks. Moreover, based on the traditional ant-based algorithm, we propose an ant-based service-aware routing (ASAR) algorithm. The ASAR chooses suitable paths to meet diverse QoS requirements from different kinds of services, thus maximizing network utilization and improving network performance. Finally, extensive simulation is conducted to verify the effectiveness of our solution and we give a detailed discussion on the effects of different system parameters. Compared to the typical routing algorithm in sensor networks and the traditional ant-based algorithm, our ASAR algorithm has better convergence and significantly provides better QoS for multiple types of services in the multimedia sensor networks. __________ Translated from Acta Electronica Sinica, 2007, 35(4): 705–711 [译自: 电子学报]     

Fractals and wavelets

Network traffic is the outcome of many different sources, which in fact is reminiscent of chaos, that is fractals. Scaling behavior is intrinsically connected with fractals and chaos theory. It is well known that the scaling behavior of teletraffic data affects substantially the overall performance of computer networks. In fact, this behavior is taken into account during analysis, design and deployment of computer networks. Several formulas have been devised to predict queue lengths that conform to desirable QoS (quality of service), given certain traffic characteristics. However, we have not yet found a unified approach that provides good results in every possible case. We explore how elements of chaos theory and fractals can help us design better networks. Networks that provide the QoS they are designed to render.     

基于虚剩余带宽的多个路由表的多类别QoS路由

现在以及将来的网络通需要支持有QoS请求的应用,而这对于大型复杂的网络结构是一个挑战,一些研究已经解决了QoS路由的一部分问题.本文在虚剩余带宽的多个路由表的基础上提出了一种新的QoS路由,允许在多个业务类之间动态地共享链路资源.路由算法尽可能为QoS业务选择best-effort业务轻载的链路,从而整体提升网络的性能.通过进一步的仿真,可以看出在链路负载不均衡的时候,QoS业务的丢包率以及best-effort业务的吞吐量都有很大的改善.     

A QoS‐supported controlled burst retransmission scheme in OBS networks

Burst retransmission can reduce data loss in burst contention in optical burst switching (OBS) core nodes. However, uncontrolled burst retransmission may significantly increase the network load and data loss probability, defeating the purpose of retransmission. Therefore, controlled retransmission should be studied to achieve reasonable retransmission, particularly to support quality of service (QoS) in OBS networks in which priority traffic exists. In this paper, we develop a QoS‐supported controlled retransmission scheme in OBS networks. Different from previous works in the literature, we set a different value for the retransmission probability at each contention for both high‐ and low‐priority bursts, set different retransmission probabilities for bursts of different priorities for QoS support, and propose a retransmission analytical model for OBS networks. We take into account the load at each link due to both the fresh and the retransmitted traffic and calculate the path‐blocking probability and the burst loss probability for high‐priority and low‐priority bursts to evaluate the network performance. An extensive simulation is proposed to validate our analytical model. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于智能光网络系统的配用电业务承载方案研究

配用电无源光通信网络是连接10 kV及0.4 kV设备的通信基础设施,具有高效、稳定、安全等特点。针对配电领域业务分布范围广、安全形势严峻、光纤资源规模大、运维抢修难度高等难题,设计配用电多业务综合承载及安全防护方案。提出一种光网络智能管理系统,能够实现光纤资源标签电子化、运维抢修智能化目标。基于该智能系统自动生成网络拓扑信息,研究并提出了一种面向多业务的QoS(服务质量)路由策略。通过仿真分析可知,该策略采用的群智能优化算法可为特定业务提供端到端QoS最优转发路径,保障业务的通信QoS需求,收敛速度较快,提升了通信网对电力业务的承载能力。     

Statistical appraisal of economic design strategies of LV distribution networks

This paper presents a statistical approach for assessing general LV distribution network design strategies based on a large set of realistic test networks and optimal economic circuit design. The test networks are generated using a fractal-based algorithm that allows creation of generic networks with various topological features (e.g., typical of rural/urban/mixed areas) and characterised by different numbers of substations, numbers of customers, load densities, and so forth. In comparison to standards derived from a traditional approach, that is, case studies on a small number of specific real or test networks, the proposed approach facilitates the derivation of more robust conclusions on optimal network design policies and can thus be used as a valuable tool for decision support. The methodology is exemplified through numerical applications for both urban and rural areas.     

基于排队论和QoS的电力系统主干网带宽估算

随着电力通信网以及应用系统的高速发展，对网络带宽的要求、特别是主干网带宽的要求越来越高。合适的主干网带宽估算能够为电力通信网的建设提供有力的依据。目前的网络流量估算大多局限于对正在运行的网络数据流量的实时监测，而对大型企业Intranet将来某一段时间主干带宽的估算尚无统一有效的方案。文中比较了多种网络建模与分析方法，提出了基于排队论和QoS(服务质量)的网络带宽估算方法，并以IP电话为例，给出了详细的计算过程。该方法能在对应用系统进行详细分类的基础上，利用M/M/1排队模型，直观、准确地估算出主干网络带宽。该方法适用于电力系统从地市到省公司的各种主干网带宽估算。     

Dynamic multicast traffic grooming in WDM networks

Dynamic multicast traffic grooming in wavelength division multiplexing (WDM) networks was analyzed to minimize networkwide costs and to increase the network resource utilization. A network model was developed for dynamic multicast traffic grooming with resource constraints and an algorithm that can provide quality of service (QoS) was proposed. The QoS is measured by the maximum number of lightpaths passing between the source and the destinations. The blocking probability of the algorithm was assessed in simulations. The results show that a higher QoS requirement results in higher blocking probability, and when the QoS requirement is low, changes in the QoS requirements have only small effects on the blocking probability. __________ Translated from Journal of Tsinghua University (Science and Technology), 2005, 45(4): 437–440 (in Chinese)     

一种基于策略和NSIS的端到端QoS保障框架设计

本文在分析了IETF所提出的COPS（公共开放策略服务）协议和NSIS（下一代信令）协议的基础上,提出了一种基于策略和NSIS的全IP网络端到端QoS保障框架PN-e2eQoS,该框架能够实现对全网端到端路径的资源监控,使得数据流在基于不同QoS机制的网络之间建立和维护时,对QoS要求进行统一映射处理,从而达到了端到端QoS保障的目的。同时本文也详细定义了该框架下的面向发送端和面向接收端的信令交互过程。     

Modeling and Management of Firewall Policies

Firewalls are core elements in network security. However, managing firewall rules, especially for enterprise networks, has become complex and error-prone. Firewall filtering rules have to be carefully written and organized in order to correctly implement the security policy. In addition, inserting or modifying a filtering rule requires thorough analysis of the relationship between this rule and other rules in order to determine the proper order of this rule and commit the updates. In this paper we present a set of techniques and algorithms that provide automatic discovery of firewall policy anomalies to reveal rule conflicts and potential problems in legacy firewalls, and anomaly-free policy editing for rule insertion, removal, and modification. This is implemented in a user-friendly tool called ?Firewall Policy Advisor.? The Firewall Policy Advisor significantly simplifies the management of any generic firewall policy written as filtering rules, while minimizing network vulnerability due to firewall rule misconfiguration.     

IEEE 802.11e EDCA在CFB模式下的性能分析

基于IEEE 802.11无线局域网的快速发展对服务质量提出了更高的要求,IEEE提出的802.11e提供了对QoS的支持.本文首先从理论上对比分析了IEEE 802.11中原有的DCF和IEEE 802.11e中的EDCA这两种MAC接入机制;然后运用Ns网络模拟软件,仿真网络中视频、音频和FTP数据流在不同MAC协议的网络中的性能表现,证实了IEEE 802.11e EDCA能提供QoS支持,提升WLAN性能.对IEEE 802.11e EDCA的CFB模式下各种参数的网络表现进行了仿真,证明CFB模式可以进一步提高系统的吞吐量,但是在TXOP等参数的选择上还要进行优化.     

基于相容系数的多传感器融合目标识别方法

针对车型识别技术存在类别判定冲突问题，提出基于相容系数的多传感器融合目标识别方法。首先，采用多假设思想实现多传感器异构数据聚类合并获取单帧融合检测结果；然后，计算证据之间的相容系数对证据冲突重新分配，结合Dezert-Smarandache理论(DSmT)来处理单帧融合后可能出现的证据冲突情况，并获取目标类别的准确识别结果。实测数据结果表明，该方法能克服传感器检测范围受限问题和类别判定冲突问题，目标识别准确率可达93%以上，降低了目标识别的漏检率和误检率，可达到良好的目标识别准确性能。     

移动视频业务的EQoS方案及跨层资源管理模型

在分析4G网络的链路特性、视频业务对网路资源的要求和3GPP移动网路QoS方案的基础上,针对移动视频业务在未来ICT网络中的应用特点,提出了移动视频业务扩展QoS（EQoS）方案和基于EQoS方案的跨层资源管理模型。前者引入了移动视频业务细化衡量标准,有利于移动视频业务质量指标的量化;后者在保持原有网络分层模型的基础上,通过EQoS模块实现了跨层无线资源管理。     

Resource management in LEO satellite networks

To provide truly global coverage needed by increased Personal Communication Services (PCS), a new generation of mobile satellite networks has been proposed. These low Earth orbit (LEO) mobile satellite networks handle multimedia traffic and can be used for non-real-time as well as real-time service to remote areas. Due to the many handoffs, resource management and connection admission control are important tasks for fair bandwidth sharing and QoS guarantees. Because the total link capacity has to be divided among several carriers and given the limited buffer capacity of the ATM switch, resource management is vital. It ensures the ability of the network to provide users with their negotiated QoS while protecting the network and the end-systems from congestion. We introduced a simple connection admission control (CAC) priority policy based on the delay and cell loss requirements for the investigated types of traffic. We took into account the handoff status of the satellite beams involved. Thus, we propose an onboard buffer architecture with separated buffers for new calls and intra-satellite handoff calls. The priority scheme applied is as follows: highest priority is given to CBR, followed by rt-VBR, nrtVBR and ABR.     

Fairness based channel borrowing strategy in multimedia LEO satellite communications

A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources. It provides the network with better quality-of-service (QoS) guarantees, such as new call blocking probability (CBP) and handoff call dropping probability (CDP) in multimedia low earth orbit (LEO) satellite networks. Simulation results show that, compared with other bandwidth allocation schemes, the proposed scheme offers very low call dropping probability for real-time connections while, at the same time, keeping resource utilization high. Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods. Translated from Journal on Communications, 2006, 27(8): 10–17 [译自: 通信学报]     

基于GE Smallworld GIS的停电分析系统研究

本文提出了基于GE Smallworld GIS的停电分析系统,它是建立和维护从变电站至用户馈线连通性模型的工具.该系统可对配电网有关信息进行地理聚焦定位,可在GIS视图中进行停电范围分析和模拟停电分析,是配电网操作人员的一个决策支持工具.在综合环境中它可与企业的其它信息系统相互作用,是配网综合停电管理系统成功设计和实施的关键.研究的结果表明,该系统有很好实用价值,在停电管理方面的性能非常好.     

QoS metrics modeling and analysis for neighborhood area network in smart grid applications

Recently, planning and designing of smart‐grid (SG) neighborhood area network (NAN) communication architecture has drawn wide attention of researchers. In order to establish an SG NAN scheme satisfying the requirement, a quality of service (QoS) metric is a critical demand. However, there are few studies on the implementation of an efficient QoS metric model. In this paper, we propose an innovative QoS metric model for SG NAN design. By exploring the natural characteristics of SG messages in many applications, we choose the reliability and latency of a message as the most important criteria and implement the QoS curve for evaluating the performance of any candidate communication scheme. In addition, we present the evaluation model for QoS metrics of multiple SG services in NAN. Compared to other existing QoS methods, our model is easy to use and helps to reduce the time and cost in the planning and designing of a NAN for SG. Simulation and analysis results indicate good agreement with our proposed QoS model. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

分组传送技术在智能配用电通信网的应用探讨

针对智能配用电通信网中多业务承载、业务IP化、网络融合化的需求,提出采用分组传送技术进行通信的解决方案。介绍了配用电网分层分布式架构和配用电的主要业务需求,分析了现有通信技术的特点,从多业务承载技术、QoS机制、生存性技术、OAM技术、同步技术等方面探讨分组传送技术在配用电通信网的应用可行性,并提供了一种应用模式。该探索研究为分组传送技术在配用电通信网的应用奠定了基础。     

MPLS体系、性能及应用

就MPLS的产生背景，MPLS标签，MPLS流量工程，MPLS VPN应用等展开叙述，MPLS的问世可以保证如语音传送，视频服务，多媒体信息服务传输等应用业务按各应用的特性正确予以传送。MPLS网络中数据的传输告标签引导，标签是固定长度的，无结构的值，采用MPLS流量工程可以避免引起网络阻塞，为用户提供更好的服务。在Cisco IOS网络中，MPLS虚拟专用网提供了发展和管理第3层VPN骨干服务的能力。