EVCP： a convergence time improved high-speed transport congestion control protocol

The Internet evolves to incorporate very-high-bandwidth optical links and more large-delay satellite links. TCP faces new challenges in this unique environment. Theory and experiments showed that TCP becomes inefficient and is prone to be unstable as the per-flow product of bandwidth and latency increases, regardless of the queuing scheme. Variable-structure congestion Control Protocol (VCP) is proposed to address these problems. However, VCP has problem in terms of convergence time, i.e., it takes a long time for a new VCP flow to achieve fair bandwidth allocation if the existing VCP flows have large con- gestion windows. This paper proposed an Extended Variable-structure congestion Control Protocol (EVCP), which adopted a convergence controller. The basic idea of convergence controller is that if a flow has larger window than its fair window, its congestion window should be decreased more aggressively than usual in Multiplicative Decrease (MD) phase. Simulations showed that EVCP has better performance in terms of convergence time while keeping the advantages of VCP.     

TCP performance evaluation over AODV and DSDV in RW and SN mobility models

INTRODUCTION Widely varying mobility characteristics are ex- pected to have significant impact on the performance of routing protocols. Many previous works focused on the routing protocols and seldom discussed the impact of mobility on the transport layer protocol. On the other hand, the performance of the transport layer protocol over different routing protocols was evalu- ated in some previous works (Ahuja et al., 2000; Dyer and Boppana, 2001), but they always used the Ran- dom Waypoin…     

卫星IP网技术

进一步发展Internet业务需要增大带宽并且要有移动性,因而卫星网与IP网结合成了热门话题.针对卫星网的信道差错率高、传播延迟长和信道不对称性对TCP传播性能有不良影响,介绍了前向纠错和自动重传两种链路差错控制方案和对TCP的改进.     

无线传输层协议与WTP的分析

本文介绍了传输层的产生的原因，总结了Internet中广泛应用的有线、无线TCP的特点，并针对无线环境，介绍了几种提高效率和可靠性的算法。最后根据WAP中的WTP协议，分析了WTP的性能和特点。     

基于TCP/IP协议的点对点通信

TCP/IP (TransmissionControlProtocol/InternetProtocol)是一种面向连接的多层网络通讯协议 ,它的出现成功地解决了异网互连通信 .其通讯的步骤为建立连接→发送数据→拆除连接 .PPP协议 (PointtoPointProtocol)是由IETF定义的点对点的协议 ,用来取代串行链路互连网络协议SLIP(SerialLineInternetProtocol) ,它为在点对点链路上直接相连的两个设备之间提供一种传送数据包的方法 .本文简述了TCP/IP及PPP的基本原理 ,并在Delphi5平台下实现了局域网的通信 ,其目的就是了解并掌握基本协议的通信原理     

基于以太网的Modbus/TCP协议的实时性研究

以Modbus和TCP传输协议为研究对象,对其协议性机理进行了的研究。在此基础上,在Quantum系列PLC的以太网通信模块与上位监控站之间,做了基于Modbus／TCP传输协议的实时性测试。其测试的结果是Modbus／TCP传输协议用于工业控制中是可行的。     

移动无线网络中TCP协议改进研究

TCP是Internet最常见的传输控制协议。本文首先介绍TCP协议的传输控制原理;然后讨论为什么传统TCP协议不适合移动无线网络,并分析移动无线网络中改善TCP协议的三种典型方法;最后总结出针对移动无线网络TCP协议改进的思路。     

基于时延无线MIMO信道的仿真与实现

本文通过对目前提出的无线MIMO信道进行总结,详细分析了MIMO信道的空时模型。为了对MIMO无线通信技术进行有效的研究与评估,在基于3GPP中的TR25.996协议的基础上,根据接收信号的平均到达角、扩展角和收发两端天线的拓扑结构,创建了一个基于时延的无线MIMO信道仿真方法。通过对时延无线MIMO模型的仿真,验证了基于时延无线MIMO信道特性。     

模糊变结构时延控制算法及在AQM中的应用

研究了带有延迟时间补偿的模糊变结构控制算法，分析了模糊变结构控制中积分因子对于时延因子的补偿机理，并基于网络拥塞路由器中TCP连接的线性化模型设计了适用于主动队列管理的时延控制算法．最后讨论了该控制算法的实现问题和参数整定，进行了仿真实验．对于TCP主动队列管理的性能分析和比较试验表明，本算法在RTT和TCP会话数量变动时保持了良好性能和鲁棒性，在丢包率、吞吐量和缓冲波动方面相比其他类似方案有明显的性能优势．     

TCP/IP协议二进制代码的分析方法

Internet的核心技术是TCP/IP协议,TCP/IP协议在Internet工作时表现为在网络中传输的二进制代码.讨论了TCP/IP协议二进制代码的方法,并举实例予以说明,该技术对于分析网络故障和处理对网络的恶意攻击都有一定的现实意义.     

IPv6: The next generation Internet Protocol

IPv4, the workhorse protocol of the currently popular TCP/ IP protocol suite, is fast becoming obsolete. The exponential growth of the Internet is the main reason that has required the creation of the next generation of Internet Protocol-IPv6. IPv6 is much more flexible and promises to take care of the address space and security issues in the foreseeable future. Part 1 of the paper lays the foundation of the various issues involved in designing the Internet Protocol and motivates the need for an upgraded version of this protocol.     

TCP/IP中网络管理协议的演变及发展

网络管理协议随着网络技术的发展处于不断的发展之中,特别是Internet中基于TCP/IP的网络管理协议.本文就TCP/IP中网络管理协议SNMP,SNMPv2,SNMPv3及RMON的技术特点、缺陷和优势进行了论述,从中可看出网络管理协议演变的过程及发展的趋势.     

Extended mobile-host-centric transport protocol

In wireless networks, data packets are lost due to channel interference and fading rather than network congestion. Thus, TCP designed for wired networks, cannot achieve a satisfying performance in wireless networks. Utilizing a cross-layer mechanism to identify the course of packet loss, we have proved that a mobile-host-centric transport protocol (MCP) can achieve higher throughput than TCP Reno and New Reno in static wireless environment. In this paper, we extend the cross-layer feedback mechanism and con...     

IPv6: The next generation internet protocol

IPv4, the workhorse protocol of the currently popular TCP/ IP protocol suite, is fast becoming obsolete. The exponential growth of the Internet is the main reason that has required the creation of the next generation of Internet Protocol-IPv6. IPv6 is much more flexible and promises to take care of the address space and security issues in the foreseeable future. In this part we explain the new features introduced in the emerging Internet Protocol standard and why they have been introduced. Harsha Stlnath is currently pursning his MS degree in Computer Science at the Center for Advanced Computer Studica (CACS) in University of Loulsiana at Lafayette, USA. His research interests include networking with an emphasis on wireless networks, distributed databases and data mining     

A novel OFDM transmission scheme with length-adaptive Cyclic Prefix

Conventional OFDM transmission system uses a fixed-length Cyclic Prefix to counteract Inter-Symbol Interferences(ISI)caused by channel delay spreading under wireless mobile environment. This may cause considerable performance deterioration when the CP length is less than the channel RMS delay spread,or may decrease the system power and spectrum efficiency when it is much larger. A novel Orthogonal Frequency Division Multiplexing(OFDM)transmission scheme is proposed in this paper to adapt the CP length to the variation of channel delay spread. AOFDM-VCPL utilizes the preamble or pilot sub-carriers of each OFDM packet to estimate the channel RMS delay spread; and then uses a criterion to calculate the CP length,which finally affects the OFDM transmitter. As illustrated in the simulation section,by deploying this scheme in a typical wireless environment,the system can transmit at data rate 11.5 Mb/s higher than conventional non-adaptive system while gaining a 0.65 dB power saving at the same BER performance.     

一种改进的DDoS攻击源端快速检测算法

从TCP协议的基本原理入手,基于TCP的三次握手原理,提出以统计源端主机发往目标地址的SYN包个数与返回的SYN／ACK包个数的差值来量化目标主机的拥塞程度,为缩短检测延迟将攻击点的个数加到检测方法中,采用改进后的非参数CUSUM方法,将连续攻击效果放大以减小检测的误警率。实验证明：较D-WARD系统,该算法在减小误警率和提高检测速度上均有很大程度的提高。     

移动IP环境下无线网络的TCP性能改进方案

传统有线网络TCP拥塞控制机制建立在拥塞是网络丢包原因的基础上,所以该机制不能适应无线网络中高误码率造成的无线链路丢包的情况.因此,我们提出一种基于移动算法的DSTCP解决方案,该机制和算法能有效地降低无线网络中的丢包率,提高信道的利用率和性能.     

Virtual and Dynamic Hierarchical Architecture: an overlay network topology for discovering grid services with high performance

This paper presents an overlay network topology called Virtual and Dynamic Hierarchical Architecture (VDHA) for discovering Grid services with high performance. Service discovery based on VDHA has scalable, autonomous, efficient, reliable and quick responsive. We propose two service discovery algorithms. Full Search Query and Discovery Protocol (FSQDP) discovers the nodes that match the request message from all N nodes, which has time complexity O(logN), space complexity O(nvg) (nvg being node numbers of each virtual group), and message-cost O(N), and Domain-Specific Query and Discovery Protocol (DSQDP) searches nodes in only specific domains with time complexity O(nvg), space complexity O(nvg), and message-cost O(nvg). In this paper, we also describe VDHA, its formal definition, and Grid Group Management Protocol.     

使用TCP/IP协议族程序实现网络管理

讲述了如何在通过TCP/IP技术组建起来的网络下，使用TCP/IP协议族中的实用工具进行网络管理及排除故障的方法，以确保网络的正常运行。     

具有时滞补偿的网络拥塞控制的研究

经过线性化处理的TCP/AQM拥塞控制模型是一个输入带有时滞的源端链路端组合系统。首先修改了带有延迟的网络拥塞控制模型;计算其平衡状态并进行线性化,采用积分变换算法进行延迟变换为无时滞的线性模型,并建立相应的状态空间模型。在模型矩阵参数抖动但有界限的条件下,应用变结构控制算法设计控制器,基于李雅普诺夫稳定性理论和线性矩阵不等式方法给出了该控制器控制的系统可到达和渐进稳定的可行条件,同时根据该条件设计网络链路端主动队列管理算法。最后,仿真结果表明了该算法的有效性。