传感器网络中基于事件信息量的公平性控制

在分析无线传感器网络现有公平性控制方法的基础上,依照新的公平性控制的基本原则实施带宽分配,即事件信息量是节点传输的有效信息量,公平性带宽分配是按事件信息量的比例来分配,如何计算带宽竞争节点所传的事件信息量是实现该基本原则的关键.针对事件信息均匀分布的情况,提出了以事件信息量为基础的公平性控制(EFFRC,event faith based fair rate control)算法,该算法将事件信息量的计算转换为事件区域大小的计算,并通过区域细分,将任意形状的事件区域大小的计算转换为若干四边形区域大小的求和,从而达到信息量计算的目的.实验表明,EFFRC算法能够有效计算事件信息量,实现公平的带宽分配.     

Mitigating server-side congestion in the Internet throughpseudoserving

Server-side congestion arises when a large number of users wish to retrieve files from a server over a short period of time. Under such conditions, users are in a unique position to benefit enormously by sharing retrieved files. Pseudoserving, a new paradigm for Internet access, provides incentives for users to contribute to the speedy dissemination of server files through a contract set by a “superserver”. Under this contract, the superserver grants a user a referral to where a copy of the requested file may be retrieved in exchange for the user's assurance to serve other users for a specified period of time. Simulations that consider only network congestion occurring near the server show that: (1) pseudoserving is effective because it self-scales to handle very high request rates; (2) pseudoserving is feasible because a user who participates as a pseudoserver benefits enormously in return for a relatively small contribution of the user's resources; (3) pseudoserving is robust under realistic user behavior because it can tolerate a large percentage of contract breaches; and (4) pseudoserving can exploit locality to reduce usage of network resources. Experiments performed on a local area network that account for the processing of additional layers of protocols and the finite processing and storage capacities of the server and the clients, corroborate the simulation results. They also demonstrate the benefits of exploiting network locality in reducing download times and network traffic while making referrals to a pseudoserver. Limitations of pseudoserving and potential solutions to them are also discussed     

End-to-end congestion control for the Internet: delays andstability

Under the assumption that queueing delays will eventually become small relative to propagation delays, we derive stability results for a fluid flow model of end-to-end Internet congestion control. The theoretical results of the paper are intended to be decentralized and locally implemented: each end system needs knowledge only of its own round-trip delay. Criteria for local stability and rate of convergence are completely characterized for a single resource, single user system. Stability criteria are also described for networks where all users share the same round-trip delay. Numerical experiments investigate extensions to more general networks. Through simulations, we are able to evaluate the relative importance of queueing delays and propagation delays on network stability. Finally, we suggest how these results may be used to design network resources     

Promoting the use of end-to-end congestion control in the Internet

This paper considers the potentially negative impacts of an increasing deployment of non-congestion-controlled best-effort traffic on the Internet. These negative impacts range from extreme unfairness against competing TCP traffic to the potential for congestion collapse. To promote the inclusion of end-to-end congestion control in the design of future protocols using best-effort traffic, we argue that router mechanisms are needed to identify and restrict the bandwidth of selected high-bandwidth best-effort flows in times of congestion. The paper discusses several general approaches for identifying those flows suitable for bandwidth regulation. These approaches are to identify a high-bandwidth flow in times of congestion as unresponsive, “not TCP-friendly”, or simply using disproportionate bandwidth. A flow that is not “TCP-friendly” is one whose long-term arrival rate exceeds that of any conformant TCP in the same circumstances. An unresponsive flow is one failing to reduce its offered load at a router in response to an increased packet drop rate, and a disproportionate-bandwidth flow is one that uses considerably more bandwidth than other flows in a time of congestion     

A new approach to ensure fairness over the Internet

Congestion signaling is an essential issue for ensuring a high network performance. Explicit congestion notification (ECN) has been proved to provide a faster indication of congestion and thus improve the QoS of a TCP/IP network. In this paper, we present a new scheme for ECN named fair in‐time marking (FIM), which employs a mechanism that as well as providing an indication of incipient congestion, assures a fair service to all the connections. To facilitate such services using FIM, we propose inclusion of some simple yet effective functionalities in the routers. This is important as the client base of the Internet is increasing rapidly and the demand for a reasonably fair service is getting stronger. Experiments show that FIM offers the best fairness, sometimes better by around 20% or more without affecting efficiency, compared with other proposed schemes for ECN. Copyright © 2004 John Wiley & Sons, Ltd.     

On the limitation of fluid-based approach for Internet congestion control

Fluid models have been the main tools for Internet congestion control. By capturing how the average rate of each flow evolves, the fluid model proves to be useful as it predicts the equilibrium point to which system trajectory converges and also provides conditions under which the convergence is ensured, i.e., the system is stable. However, due to inherent randomness in the network caused by random packet arrivals or random packet marking, the actual system evolution is always of a stochastic nature. In this paper, we show that we can be better off using a stochastic approach toward the congestion control. We first prove that the equilibrium point of a fluid model can be quite different from the true average rate of the corresponding stochastic system. After we describe the notion of stability for two different approaches, we show that a stable fluid model can impose too much restriction on our choice of system parameters such as buffer size or link utilization. In particular, under fluid models, we show that there exists a fundamental tradeoff between the link utilization and buffer size requirement for large systems, while in a more realistic setting with stochastic models, there is no such tradeoff. This implies that the current congestion control design can be much more flexible, to the benefit of efficient usage of network resources. This work was supported in part by NSF CAREER Award CNS-0545893. Do Young Eun received his B.S. and M.S. degree in Electrical Engineering from Korea Advanced Institute of Science and Technology (KAIST), Taejon, Korea, in 1995 and 1997, respectively, and Ph.D. degree in Electrical and Computer Engineering from Purdue University, West Lafayette, IN, in 2003. Since August 2003, he has been an Assistant Professor with the Department of Electrical and Computer Engineering at North Carolina State University, Raleigh, NC. His research interests include network modeling and analysis, congestion control, resource allocation, and ad-hoc/sensor networks. He is a member of Technical Program Committee of IEEE INFOCOM 2005–2007, IEEE ICC 2005–2007, IEEE Globecom 2005, and IEEE IPCCC 2006–2007. He received the Best Paper Awards in the IEEE ICCCN 2005 and the IEEE IPCCC 2006, and the NSF CAREER Award 2006.     

Realizing the Ubiquitous Network: the Internet and Beyond

Two major properties will characterize networks in the future: ‘3C everywhere’ and ‘physical interaction’. These two properties promise a computing infrastructure that seamlessly and ubiquitously aids users in accomplishing their tasks and that renders the actual computing devices and technology largely invisible. This paper begins by providing a brief overview of the emerging technologies that may influence the new ubiquitous network (UbiNet) architecture. The following section presents our STONE (Service Synthesizer on the Net) project at the University of Tokyo. We designed STONE to provide distributed transparency, service consistency, and context-awareness, and explored communication and computation technologies in a sensor-instrumented environment.     

Ensuring fairness among ECN and non‐ECN TCP over the Internet

Explicit Congestion Notification (ECN) has been proved to provide a fast indication of incipient congestion and thus better the performance of a TCP/IP network. In this work, we carry out investigations on gateway or router performance in providing fairnesss when both FIM ECN‐capable and non‐ECN‐capable connections are employed. We propose a new packet‐dropping scheme called Fair In‐time Dropping (FID) which drops packets from a connection upon detecting an incipient indication of congestion depending on its share of gateway or router buffer occupancy. We also show that a combination of FIM and FID offers the best fairness compared with a combination of FIM along with other dropping schemes. Copyright © 2003 John Wiley & Sons, Ltd.     

TCP Vegas: end to end congestion avoidance on a global Internet

Vegas is an implementation of TCP that achieves between 37 and 71% better throughput on the Internet, with one-fifth to one-half the losses, as compared to the implementation of TCP in the Reno distribution of BSD Unix. This paper motivates and describes the three key techniques employed by Vegas, and presents the results of a comprehensive experimental performance study, using both simulations and measurements on the Internet, of the Vegas and Reno implementations of TCP     

工业互联网推动工厂网络与互联网融合发展

从目前工厂网络面对智能制造需求存在的问题出发,分析工厂内部网络"三化(IP化、扁平化、无线化)+灵活组网"的发展趋势,指出工业生产与互联网业务模式的融合体现为四大类:信息技术(IT)系统与互联网的融合、操作技术(OT)系统与互联网的融合、企业专网与互联网的融合、产品服务与互联网的融合,并认为工厂网络与互联网的融合仍将基于目前以IP技术为基础的互联网技术体系。     

A comparison of congestion control and time slot algorithms in Internet transmission performance

The characteristics of TCP and UDP lead to different network transmission behaviours. TCP is responsive to network congestion whereas UDP is not. This paper proposes two mechanisms that operate at the source node to regulate TCP and UDP flows and provide a differential service for them. One is the congestion‐control mechanism, which uses congestion signal detected by TCP flows to regulate the flows at the source node. Another is the time‐slot mechanism, which assigns different number of time slots to flows to control their flow transmission. Based on the priority of each flow, different bandwidth proportions are allocated for each flow and differential services are provided. Simulation results show some insights of these two mechanisms. Moreover, we summarize the factors that may impact the performance of these two mechanisms. Copyright © 2001 John Wiley & Sons, Ltd.     

互联网与网络安全

随着互联网的快速发展和网络用户的不断攀升,网络安全问题也日益凸显,从网络信息安全的脆弱性、网络安全的主要技术、常见网络攻击方法及对策、网络安全建设等方面剖析了当前网络信息安全存在的主要问题,并对常见的网络攻击从技术层面提出解决方案,希望通过网络安全建设逐步消除网络信息安全的隐患。     

无线自组网与Internet互连中TCP流公平性分析与改进

通过实验与分析揭示了基于IEEE 802.11 MAC的无线自组网与Internet互连时TCP流间的不公平性现象及其产生原因,并基于网关带宽占用对互连环境下TCP流间的公平性进行定义,提出了一种基于网关动态带宽控制的TCP流公平性解决方案TCP-GAFC。TCP-GAFC只在网关节点上进行实现,无需修改TCP协议和MAC协议,具有很好的适用性和可扩展性。仿真实验表明,TCP-GAFC显著地改进了互连环境下TCP流间的公平性,并能达到合理的总吞吐量。     

Nonlinear dynamics in Internet congestion control model with TCP Westwood under RED

of the congestion control system with TCPW connections and RED gateway.     

光因特网中的网络管理

近年来，随着Internet的出现和繁荣，IP业务量呈现爆炸式的增长，同时，wDM由于其巨大的带宽和成熟的技术正成为未来的主导传输技术。因此，人们提出了光因特网的概念来将IP和wDM两种技术有效结合起来。随着光因特网概念的提出，光因特网中的控制和管理技术也得到了广泛的研究，不过当前的研究主要集中于对控制技术的研究。但是，当前控制平面方法还有很多问题有待解决，同时，要满足这个新型网络最重要的要求即实现业务的快速提供和故障恢复，采用管理平面的方法也同样可以实现。光因特网网络管理不仅要能够对IP网和光网络进行管理，还要能够对两种技术进行集成的管理，以更好地利用和维护网络资源。本主要研究光因特网中的网络管理技术，提出了光因特网管理模型、管理体系结构以及管理信息模型，并对光因特网中管理信道的实现进行了研究。     

计算机网络远程无线互联及网络优化

随着互联网时代的高速发展与现代先进科学技术手段的合理应用,我国的计算机网络远程无线互联的低成本、高便利等多种优点集于一身的特点,都使其在我国的各行各业发展中得到了广泛的应用,比如手机中的短信业务、无线上网卡等,都充分地体现出无线互联的技术应用。无线互联,就是指在无线网络基础上,实现互联网的建立。通过对计算机网络远程无线互联的应用以及实施,为人们的日常生活水平提高作出了巨大的贡献,在丰富了人们生活的同时也为我国的综合发展起到了重要的作用。目前,许多学者将无线互联技术作为主要的研究对象进行分析,而文章也将对计算机网络远程无线互联及其网络优化进行研究。     

Internet网络延迟分析

对Internet网络延迟进行较为全面的分析，指出排队延迟是Internet上的主要延迟，提出一种新的减少网络延迟，改善Internet服务质量的方法，并用排队论加以分析。     

Bearer Network of the Future Internet

The future Internet needs to support broadband services,fixed services,mobile services and a combination of these. Such a wide range of services and multi-processes between users demands flexible and effective network-wide resource scheduling and support. Two approaches are currently being studied:reformative method and revolutionary method. The reformative method,based on existing technology,uses various techniques to achieve improvement. Revolutionary method seeks to address future business demands by com...     

为因特网加速的内容配送网络

内容配送网络(CDN)在现有网络基础设施之上新建一层重叠网,对因特网中的信息流进行优化,从而提高网络的使用效率。CDN有三个独立的组成部分:内容传递、内容路由和性能度量。从CDN在美国的应用看,该业务的提供商对网络现有问题的解决存在不同观点,采用的技术也不相同但建立良好的伙伴关系和客户关系对所有CDN提供商的发展都至关重要。