DLD-MAC:一种区分服务的低时延传感器网络MAC协议

针对现有无线传感器网络MAC协议不能提供区分服务和传输时延较大的问题,在经典多跳传输协议DW-MAC的基础上,提出了一种具有区分服务功能的低时延MAC协议—DLD-MAC(Diffserv-based Low-Delay MAC)。其基本思路是让高优先级数据选择更小的竞争窗口,以降低时延和能耗。Markov建模分析表明,DLD-MAC能对不同优先级的业务流进行很好的服务区分,而且相较于传统的无线传感器网络MAC协议,其在时延性能上有显著优势,能更有效地保障服务质量。     

支持VoIP电话紧急呼叫的QoS保障方案及其仿真

紧急呼叫在Internet上是一个非常重要的任务,在有限带宽情况下尽可能多地接受VoIP呼叫是必要的;但同时为紧急呼叫提供高质量的服务也是必须的。本文基于一种保证端到端的VoIPQoS服务模型,提出了新的方案。该方案基于DiffservAF服务模型、SIP信息段和一种通过观察VoIP数据流信息而设计的呼叫接纳信令,来为紧急VoIP提供高质量服务。最后,根据网络仿真结果性能指标,验证提出方案的合理性、可靠性。     

解决IP服务质量的综合方案及其应用

为了使IP网能满足音频、视频等实时业务的要求．研究在IP网上对不同业务提供相应的服务质量(QoS)保障是很重要的。文中重点对资源预留协议(RSVP)、综合服务(IntServ)以及区分服务(DiffServ)等几种QoS方案进行分析和讨论，并提出两个合成方案，即IntServ与DiffServ结合以及IP融入ATM的模型，可以解决网络中的延迟问题，实现网络资源的共享，并阐述了如何在电力通信网中利用MPLS技术传送关键业务。     

Design and performance evaluation of a fuzzy based traffic conditioner for differentiated services

The current Internet can only provide the best-effort services. By growing the Internet and its applications, new services with different requirements are developed. The differentiated services (Diffserv) [S. Blake, M. Carlson, E. Davies, Z. Wang, W. Weiss, An Architecture for Differentiated Services, IETF RFC 2475, 1998; K. Nichols, V. Jacobson, L. Zhang, A Two-bit Differentiated Services Architecture for the Internet, IETF RFC 2638, July 1999; T. Li, Y. Rekhter, A Provider Architecture for Differentiated Services and Traffic Engineering (PASTE), IETF RFC 2430, October 1998] is a scalable model for providing end-to-end quality of services. A Diffserv router consists of different components including classifier, meter, marker, dropper, shaper and scheduler. In this paper, we use the benefits of the fuzzy logic controller to design a fuzzy based traffic conditioner for Internet differentiated services. Our proposed model consists of three major parts: a fuzzy meter/marker (FM), a fuzzy active queue management (FAQM) algorithm and a fuzzy scheduler (FS). The proposed FM used to measure and mark the input traffic is based on the single rate three colors meter (srTCM) mechanism [J. Heinane, et al., A Single Rate Three Color Marker, RFC 2697, September 1999]. The FM meters an IP packet stream and marks its packets GREEN, YELLOW, or RED. The proposed FAQM is a fuzzy implementation of the well-known BLUE active queue management (AQM) algorithm [W. Feng, D. Kandlur, D. Saha, K. Shin, BLUE: A New Class of Active Queue Management Algorithms U. Michigan CSE-TR-387-99, April 1999]. To achieve a good throughput and reasonable packet loss ratio, the proposed FAQM mechanism employs a fuzzy logic controller. The third part of the proposed fuzzy traffic conditioner is FS. It is based on the traditional weighted fair queue (WFQ) mechanism [A. Demers, S. Keshav, S. Shenker, Analysis and simulation of a fair queueing algorithm, in: SIGCOMM Symposium on Communications Architectures and Protocols, Austin, Texas, September 1989, pp. 1–12] that tunes the weight of each queue by a fuzzy logic controller. To evaluate the performance of the proposed model, we developed a software in C++ environment to simulate it. Different network topologies with different traffic parameters were performed. The simulation results easily helped us to judge the merit of the proposed FM, FAQM and FS because of their remarkable performance over the traditional non-fuzzy mechanisms.     

DiffServ中AF业务带宽分配公平性

通过在opnet6.0下进行计算机仿真实验及数据分析,研究Diffserv网络中AF业务类间和AF业务类里分别在欠载,过载情况下带宽分配的公平性问题,发现AF类间有较好的公平性,而在AF类里,受RTT,TCP连接数目,非响应流等因素的影响,并没有较好的带宽分配公平性。     

Rule-Based Building-Block Architectures for Policy-Based Networking

We developed two rule-based building-block architectures, i.e., pipe-connection and label-connection architectures, for describing complex and structured policies, especially network QoS policies. This study focuses on the latter. The relationships or connections between building blocks are specified by the data flow and control flow between them. The data flow is specified by tags, including virtual flow labels (VFLs), which are data attached to outside packets. The control flow can be classified and specified by four control structures: concatenation, parallel application, selection, and repetition. We have designed fine-grained and coarse-grained building blocks and methods for specifying data flow and control flow in differentiated services (Diffserv), and implemented the coarse-grained ones in a policy server. Two cases of building-block use are described, and we concluded that there are five advantages of building-block-based policies, i.e., expressibility, uniform semantics, simplicity, flexibility, and management-task-oriented design. We also developed techniques for transforming building-block policies into executable ones, which are called policy division and fusion.     

一种基于用户的自适应类选择算法

针对QoS管理模型中的自适应处理模块进行了深入研究,提出了基于用户的自适应类选择算法,该算法不仅能够提高用户的满意度,而且能够均衡各个服务类别在网络中的负荷,保证应用的服务质量,实现QoS管理的自适应性.算法采用了基于下一时刻的预测方法进行估算,从而优化了参数取值,使用户选择的服务类别更加精确.     

Design and evaluation of inter‐bandwidth broker signaling

Bandwidth brokers (BBs) have been proposed for providing end‐to‐end quality of services (QoS) in differentiated services (Diffserv) networks. As a single entity in each domain, a BB aims at performing both intra‐ and inter‐domain resource management on behalf of its domain. There have been plenty of BB studies for intra‐domain resource management. However, how a BB can perform inter‐domain resource management in a scalable and deployable manner is still an open issue. In this work, we present the design, implementation and evaluation of an inter‐BB communication protocol that is used by each BB to communicate with its neighboring BBs for inter‐domain QoS resource management. The proposed model uses a destination‐based aggregation scheme in which reservations are aggregated as they merge through the destination region. The destination‐based aggregation improves inter‐domain state and signaling scalability. The protocol also performs traffic engineering to increase inter‐domain resource utilization. The implementation and simulation results verify the achievements of our model. Copyright © 2008 John Wiley & Sons, Ltd.     

两比特区分服务实现策略研究

1.引言区分服务是近两年的一个研究热点,其目的是在传统的IP分组交换网络上为用户提供较大粒度的服务质量保证。采用的实现手段是简化网络内部节点的服务机制和简化网络内部节点的服务对象。区分服务的基本思想是在网络边缘节点保存流状态信息,并根据用户的流规定和资源预留信息对流入分组进行分类、整形、聚合为不同的流聚集,并将处理结果信息保存在IP包头的DS字段中,称为DS标记(DSCP)。内     

基于MPLS承载架构的IMS网络QoS研究

在全IP化网络环境下提供高等级的Qos保证是IMS商用化的前提.本文在对3GPP IMS体系结构的Qos策略控制机制进行分析后,给出了从核心网和承载网多个层次实现IMS网络端到端的QoS保证的解决思路.