Policy conflict analysis for diffserv quality of service management

Policy-based management provides the ability to (re-)configure differentiated services networks so that desired Quality of Service (QoS) goals are achieved. This requires implementing network provisioning decisions, performing admission control, and adapting bandwidth allocation to emerging traffic demands. A policy-based approach facilitates flexibility and adaptability as policies can be dynamically changed without modifying the underlying implementation. However, inconsistencies may arise in the policy specification. In this paper we provide a comprehensive set of QoS policies for managing Differentiated Services (DiffServ) networks, and classify the possible conflicts that can arise between them. We demonstrate the use of Event Calculus and formal reasoning for the analysis of both static and dynamic conflicts in a semi-automated fashion. In addition, we present a conflict analysis tool that provides network administrators with a user-friendly environment for determining and resolving potential inconsistencies. The tool has been extensively tested with large numbers of policies over a range of conflict types.     

基于DiffServ体系的IPv6网络QoS保证技术

面对对延迟、延迟抖动、丢包率等方面要求较高的多媒体业务在IP网络上的大量应用,IPv6协议相较于IPv4协议对QoS有更好的支持。本文提出了一种基于DiffServ体系结合RSVP信令协议的IPv6网络的QoS保证技术,在接纳控制策略、带宽分配策略等方面进行了阐述。本技术在保持了DiffServ网络灵活性和扩展性的基础上,充分利用了网络资源,提供了端到端的QoS保证。     

On the stability of adaptive Service Level Agreements

We consider some implications of non-linear feedback, due to policy combinatorics, on policy-based management of networked services. We pay special attention to the case where the monitoring of certain aspects of Service Level Agreements is used to alter future policy dynamically, according to a control feedback scheme. Using two simple models, we show that nonlinear policies are generally unstable to service provision, i.e. provide no reliable service levels (QoS). Hence we conclude that automated control by policy-rule combinatorics can damage quality of service goals.     

未来网络下的移动MPLS连接

主要阐述MPLS如何被应用到未来网络的移动连接点中。随着在MPLS中应用DiffServ，QoS容易得到保证，采用分层技术，在切换中质量的损失能够被减少，用户能获得实时的应用。要使得MPLS技术最终应用到骨干网中，对QoS、安全性以及DiffServ等问题的进一步研究和完善是必不可少的。     

基于Mobicast的传感器追踪网动态分簇QoS组播方案

针对监测区域中移动目标的跟踪问题,提出基于Mobicast的动态分簇组播路由方案,簇头节点负责对节点入簇的审查和管理,并根据网络拓扑环境和节点自身状况的改变而动态调整分簇策略,最大限度地提高组播效率和网络性能。通过调整节点入簇门限条件,使得只有性能最优的节点才能参于Mobicast会话;引入自感知技术,动态评估当前组播服务质量(quality of service,QoS)需求;利用矩阵编码和线性规划技术实时选择最佳分簇策略。分析和仿真结果表明,与现有Mobicast路由协议相比,本方案具有较低的平均时延和能耗,以及良好的QoS性能。     

Simultaneous allocation of DGs and remote controllable switches in distribution networks considering multilevel load model

Reliability improvement and loss reduction are two important goals in optimal sizing and siting of distributed generations (DGs). Also, remote controllable switches can be utilized in distribution networks to increase the role of DGs in reliability improvement. Therefore, this paper presents a GA-based method to allocate simultaneously DGs and remote controllable switches in electric distribution networks. The goal of proposed approach is reliability improvement and energy loss reduction. The optimal sizes of distributed generators are also determined during the optimization procedure. A multilevel yearly load model is utilized to achieve the optimal solution. Numerical studies on a 33-bus distribution network show satisfactory results.     

Role-Based Access Control for XML enabled multi-protocol management gateways

While security is often supported in standard management frameworks, security is of major importance in the management plane. In this paper we address the provisioning of a security “continuum” for management frameworks based on multi-protocol gateways. We provide an in depth security extension of such a gateway using the Role Based Access Control paradigm and show how to integrate our approach within a broader XML-based management framework. Two case studies are investigated: while the first one proposes to map an XML-based RBAC policy to SNMP access control model, the second one maps the same policy to CLI security levels. The target objective is to provide consistent access control policies not only locally on each device whatever be the network management framework but also globally through the managed domain.     

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.     

基于IMS的动态QoS控制

在介绍IMS体系架构和基于策略的服务质量(QoS)服务模型的基础上,描述了IMS网络中动态QoS和服务等级协议(SLA)管理的机制.通过简单的SIP信令,信息安全管理体系(ISMS)实现用户和服务提供者之间SLA的重协商,可以保证在IMS网络中业务传送的动态的QoS实现.     

Using sensor networks for highway and traffic applications

Wireless sensor networks have been used for a variety of applications. However, many highway and traffic applications have not been tapped, primarily sensor networks for highway and traffic algorithms that alleviate generic problems such as highway congestion. This is due to the fact that sensor network technology is a very recent development. Since sensor networks are relatively new, not many applications have been explored in depth. Utilizing the new generation of TinyOS micaboard mote sensors, miniaturized sensors that utilize TinyOS, an event-based operating environment written in code similar to stylized C, the article focuses on how to achieve the best possible data results from sensor network applications and setups for traffic/highway goals. How to use sensor-network graphs for optimal placement of sensors in a network so as to minimize work and to achieve the best possible, and most accurate, signal-strength localization measurements is also be a primary focus. Also discussed is a method that optimizes the tradeoff between energy and accuracy using a variety of activation policies. Finally, simulations and distancing experiments of indoor and outdoor data are provided to encourage similar sensor work.     

话音业务在IP网络中的实现

阐述了IP网络中话音业务的实现形式,即IP电话的原理、特点、以及其 如何在IP网络中实现的过程,并对IP电话在电力专网中的延时作了详细论证,最后分析了网络保证IP电话服务质量的一些措施。     

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.     

MPLS 的服务质量

随着网络流量的不断增加，网络的业务范围不断拓展，如IP Phone,IP Fax，可视电话等，各种实时与多媒体业务对数据传输提出了低时延，低抖动等更高的要求，传统的IP网络已经很难保证QoS，这已成为网络进一步发展的瓶颈。为此，IETF提出了IP网络中实现了QoS的2种模型；综合服务模型和差分服务模型，其中差分服务模型是发展方向。与此同时，对QoS具有有良好保证的MPLS技术也应运而生，面介绍了2种模型的基本概念之后，讨论了MPLS对QoS姝具体技术实现，诸如按照传统路由器的方式进行选路的拓扑驱动MPLS，为特定服务的IP包创建隧道的约束路由的MPLS。     

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。     

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.     

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.     

A controllable multi‐replica routing approach for opportunistic networks

Opportunistic networks take full advantage of opportunistic encounters among nodes to transfer packets. According to the characteristics of the limited energy of nodes and the frequent link variation in opportunistic networks, we introduce a novel routing metric that comprehensively takes into consideration the energy consumption of nodes, the probability of relay nodes meeting their destination, the time‐to‐live of the packet, and the approximate number of packet copies. Based on this metric, we propose a controllable multi‐replica routing approach in which a single‐branch diffusion strategy is applied to achieve the goal of dynamically controlling the number of replicas of packets. Our simulation results show that the proposed approach can avoid excessive load on individual nodes, guarantee the energy fairness among nodes, prolong the network lifetime, and effectively improve the delivery ratio of packets. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Adaptive bandwidth framework for provisioning connection-level QoS for next-generation wireless cellular networks

The next generation of wireless cellular networks is expected to support real-time multimedia services with different classes of traffic and diverse bandwidth requirements. Bandwidth is a scarce resource in wireless networking that needs to be carefully allocated amid competing connections with different quality of service (QoS) requirements. In this paper, an adaptive framework for supporting multiple classes of multimedia services with different QoS requirements in wireless cellular networks is proposed. The framework combines the following components: (1) a threshold-based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes among different classes of handoff calls by assigning a threshold to each class; (2) an efficient threshold-type call admission control (CAC) algorithm; and (3) a bandwidth adaptation algorithm (BAA) that dynamically adjusts the bandwidth of ongoing multimedia calls to minimize the number of calls receiving lower bandwidth than they had requested. Numerical results show that the proposed adaptive multimedia framework outperforms existing non-adaptive schemes in terms of the handoff call dropping probability and effective utilization.     

QoS on LEO satellites

This paper discusses the role played by wireless network infrastructure in mobile commerce applications. The user's perception of service quality depends on the available resources and capabilities of the network. The new generation of low earth orbit (LEO) mobile satellite networks, deployed at altitudes ranging from 500 km to 2000 km, are well suited to handle multimedia traffic and to offer end-users equipped with hand-held devices at low cost-per minute access to network services. A wide range of multimedia services and applications are expected to provide users with QoS based asynchronous transfer mode (ATM) technology. LEO satellite networks provide significant wide area coverage, unique broadcast capability, ability to meet different QoS requirements, the ability to communicate with hand-held devices and low cost access. The main resources in the LEO networks are satellite radio bandwidth and the buffer capacity of the onboard ATM switch. The most important ATM resource management function is connection and call admission control. The real objective of this article is to introduce the general framework of resource reservation in multimedia LEO satellite networks which offers a unified approach to handle all the important aspects of resource reservation and radio-resource management functions required by E-commerce and mobile commerce applications.     

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。