Improved WWW multimedia transmission performance in HTTP/TCP overATM networks

Transmission control protocol/Internet protocol (TCP/IP) is the de facto standard of the networking world. It dynamically adjusts routing of packets to accommodate failures in channels and allows construction of very large networks with little central management. But IP packets are based on the datagram model and are not really suited to real-time traffic. In order to overcome the drawbacks, a new network technology, ATM, is proposed. ATM provides quality of service (QOS) guarantees for various classes of applications and in-order delivery of packets via connection oriented virtual circuits. Unfortunately, when ATM is to be internetworked with the existing network infrastructure, some special signaling, addressing and routing protocols are needed. IP over ATM is one of the methods proposed by IETF. It allows existing TCP/IP applications to run on ATM end-stations and ATM networks to interconnect with legacy LAN/WAN technologies. But the performance of TCP/IP over ATM leaves something to be desired. Partial packet discard (PPD) and early packet discard (EPD) are two schemes to improve its performance. This paper proposes a “selective packet retransmission” scheme for improving HTTP/TCP performance when transmitting through ATM networks. In selective packet retransmission, we take advantage of the property of humans' perception tolerance for errors to determine whether to retransmit a corrupted TCP segment or not. For lossable data, such as images, when an error occurs because of cell losses, it will not be retransmitted. The simulations show that, for the same buffer size and traffic load, selective packet retransmission performs better than PPD, EPD, and plain TCP over ATM     

网络流量测量与监控系统的设计与实现

在基于TCP/IP网络的SNMP管理协议的基础上,设计完成了B/S模式的动态网络监控系统,实现了网络流量数据获取,网络报文数据获取,流量分析与实时监控的功能。通过重组、分析所获得的数据,将其还原成完整的HTTP、FTP、TELNET应用的内容,并建立保存相应记录的数据库。     

Measuring IP and TCP behavior on edge nodes with Tstat

Field measurements have always been the starting point for network design and planning; however, their statistical analysis beyond simple traffic volume estimation is not so common. In this paper we present and discuss Tstat, a tool for the collection and statistical analysis of TCP/IP traffic, which, in addition to recognized performance figures, infers TCP connection status from traces. Besides briefly discussing its rationale and use, we present part of the performance figures that can be obtained, and we highlight the insight that such figures can give on TCP/IP protocols and the Internet, thereby supporting the usefulness of a widespread use of Tstat or similar tools.Analyzing Internet traffic is difficult because a large amount of performance figures can be devised in TCP/IP networks, but also because many performance figures can be derived only if both directions of bidirectional traffic are jointly considered. Tstat automatically correlates incoming and outgoing packets. Sophisticated statistics, obtained through data correlation between incoming and outgoing traffic, give reliable estimates of the network performance also from the user perspective.Tstat computes over 80 different performance statistics at both the IP and TCP layers, allowing a good insight in the network performance. To support the latter statement, we discuss several of these figures computed on traffic measurements performed for a time period equivalent to more than three months spread during the years 2000–2003 on the access link of Politecnico di Torino.     

Data packet intercepting on the internet: How and why? A closer look at existing data packet-intercepting tools

The Internet constitutes a means of communication in terms of which millions of messages and huge chunks of data are electronically sent millions of miles across the globe each day thanks to the Transmission Control Protocol/Internet Protocol (TCP/IP). One of the functions of the TCP/IP is to break up each of these messages into smaller entities of equal length. Such an entity is known as a ‘datagram’ or a ‘data packet’. The Internet, however, already disposes of many tools/applications that can intercept a TCP/IP datagram. The reasons for intercepting a TCP/IP datagram vary from application to application. Some applications, for example, intercept a data packet or datagram to execute harmful effects on it, mostly to terrorize the sender and/or the receiver of such packet or datagram. Some applications, on the other hand, might want to monitor a packet or datagram for security reasons. Still other applications might merely want to intercept a data packet or datagram to manage flow control and other network-management aspects. Packet intercepting can, therefore, be a useful tool in any TCP/IP-based application aimed at monitoring or intercepting TCP/IP data packets or datagrams.     

领域专用低延迟高带宽TCP/IP卸载引擎设计与实现

针对量化高频交易应用场景对数据传输低延迟高带宽的需求,定制一种领域专用的TCP/IP协议栈,并将其卸载到专用硬件加速模块上。采用模块化设计实现专用硬件逻辑,并与FAST协议硬件加速模块共同构成完整的低延迟高带宽高频交易系统。通过调整最大报文长度,实现64 Byte数据对齐,提升内核与高带宽内存（HBM）间的读写速率,并对内存结构进行优化,实现主机端与HBM间的4通道并行读写管理。对各功能模块进行数据流优化,最终构建全流水线架构。模块间统一使用AXI4-Stream接口连接,并绕过内存进行数据传输,实现传输性能的提升。实验结果表明,TCP/IP卸载引擎在Xilinx Alevo U50数据中心加速卡上可获得38.28 Gb/s的网络吞吐率,基础网络通信穿刺延迟最低为468.4 ns,在叠加FAST解码协议后延迟为677.9 ns,与传统软件处理网络堆栈（Intel i9-9900x+9802BF）的方式相比,TCP/IP引擎的吞吐率提升1倍,延迟降低为1/12,且延迟稳定,波动范围在10 ns左右,在满足量化高频交易场景需要的同时,有效减轻了CPU的负载。     

隧道视频监控系统研究与设计

设计了一种针对高速公路,基于IP网络的隧道视频监控系统。系统具有自动视频切换、视频录制、车速提醒和车流量统计等功能。系统基于TCP／IP协议和．NET平台,所设计的逻辑结构不仅方便了各监控系统的级联,也方便了开发人员开发系统软件。     

Protocol wrappers for layered network packet processing inreconfigurable hardware

A library of layered protocol wrappers processes Internet packets in reconfigurable hardware. Collectively, the wrappers simplify and streamline the implementation of high-level networking functions by abstracting the operation of lower-level packet processing functions. The library synthesizes into field-programmable gate array (FPGA) logic and is utilized in a network platform called the field-programmable port extender (FPX). The library processes asynchronous transfer mode (ATM) cells, ATM adaptation layer 5 (AAL5) frames, Internet protocol (IP) messages, and user datagrarn protocol (UDP) packets directly in hardware. Applications can process data at several layers of the protocol stack using the library of wrappers discussed in this article. Layers are important for networks because they let applications abstract from above and below details of the network protocols. At the lowest layer, networks modify raw data passing between interfaces. At higher levels, the applications process variable length frames or IP packets.A network platform called the field-programmable port extender (FPX) streamlines and simplifies network transmission processing directly in hardware     

支持综合业务的Internet-ATM网络及互联

文中阐述了Ｉｎｔｅｒｎｅｔ上综合业务的模式,介绍了资源预订协议ＲＳＶＰ、Ｉｎｔｅｒｎｅｔ流协议ＳＴ－ＩＩ、资源预先预订协议ＲｅＲＡ和几种主要的Ｉｎｔｅｒｎｅｔ与ＡＴＭ主干网络的互联协议以及传统的ＴＣＰ／ＩＰ协议族的报文在ＡＴＭ网络中传送的协议ＩＰ ｏｖｅｒＡＴＭ;阐述了局域网模拟ＬＡＮＥ的体系结构及其实现的一个实例和ＡＴＭ上支持多种网络层议（如ＩＰ,ＩＰＸ／ＳＰＸ,ＡｐｐｌｅＴａｌｋ等）的规范ＭＰ     

网络数据包截获及分析工具的设计

本文主要讨论了在以太网（Ethernet）环境下的TCP／IP（其中IP协议的版本是IPv4）数据包的截获与分析技术。通过使用该技术,可以让一台主机能够接收流经该主机的所有数据包,而不理会数据包包头中目的地址的内容。这种技术在网络安全及网络管理领域有着举足轻重的地位。本系统利用套接字（Socket）对网卡的编程来实现对数据包的截获及分析。     

The Internet in space: problems and solutions

With the advent of direct broadcast satellites and inexpensive minidishes, satellite broadcasters are competing with cable television providers by delivering hundreds of channels of digital video services to millions of customers without a wired infrastructure. Many of these broadcasters also want to compete with Internet service providers by delivering high-speed Internet access to homes and businesses. If satellite services have their way, users will no longer have to wait to enjoy multimegabit Internet data connections until the telephone company provides them with fiber-optic cable. The paper considers how space-based Internet service must overcome a fundamental problem before it can realize its full potential. While it is possible to bounce Internet data packets off geosynchronous-Earth-orbit (GEO) communication satellites, the protocol that ensures that the packets will arrive safely (TCP/IP) also slows satellite-based traffic to a relative crawl. This is because in space TCP/IP must carry data over distances that are much longer than the protocols were designed for. This creates transmission delays that make it impractical to download the large files of data, including images and multimedia products, that many organizations need. However, researchers who are looking for solutions to this problem have come up with several promising proposals     

网络数据包截获及分析工具的设计

本文主要讨论了在以太网(Ethernet)环境下的TCP/IP(其中IP协议的版本是IPv4)数据包的截获与分析技术。通过使用该技术,可以让一台主机能够接收流经该主机的所有数据包,而不理会数据包包头中目的地址的内容。这种技术在网络安全及网络管理领域有着举足轻重的地位。本系统利用套接字(Socket)对网卡的编程来实现对数据包的截获及分析。     

基于EI技术的嵌入式系统接入Internet解决方案

介绍了EI技术和基于EI技术的单片机接入以太网和Internet的解决方案,并研究了网卡驱动程序的编写和TCP/IP协议的精简.本设计硬件主要由P89C61X2BN和RTL8019AS组成,单片机P89C61X2BN作为控制器来控制RTL8019AS收发数据.软件设计主要由网卡驱动程序和嵌入式TCP/IP协议栈组成,来实现数据包的收发和处理.此方案不仅成本低,而且可以实现500Kbps以上的传速率,满足了嵌入式系统的Internet控制要求.     

TCP over satellite...the final frontier

Communication satellites are now being used to transport TCP/IP traffic between distant locations, and to offer Internet access. Satellites have thus become the celestial link of the Internet, an “instant” infrastructure in the sky. The rapid growth of satellite communications is evolving the TCP/IP protocol suite in positive ways. In particular, enhancements to the Transmission Control Protocol (TCP) to address the challenges of satellite transmission will benefit all high-bandwidth TCP communications. TCP is the predominant unicast transport protocol used by Internet applications such as Telnet, FTP, and HTTP. The ability of TCP to maximize the link utilization of a satellite channel is being challenged by the inherent delays associated with space communications and some of TCP's own behaviors. The author discusses the basics of using TCP for satellite transmission and describes the changes you can expect to see in the TCP protocol itself as a result of the increase in use of satellites for TCP/IP traffic     

局域网网线软件锁的设计与实现

系统基于TCP／IP中的ICMP协议的工作原理,利用VB6．0编程语言封装ICMP数据包,并通过Windows操作系统API网络接口函数在局域网中发送,从软件开发的角度探索网线软件锁的实现方法和步骤．     

基于倒排列表的网流索引检索与压缩方法

随着计算机的广泛应用以及互联网的飞速发展,互联网流量呈现爆炸式增长的态势。为了应对日益严重的网络滥用以及网络安全事件,出于安全取证的需要,必须对互联网流量进行收集、存储和分析。互联网流量的监控需要及时统计网络流量的源地址、目的地址、源端口、目的端口、协议、时间戳等信息,以便进行流量统计和综合分析。但是网络流量信息是海量的,如何快速检索相关流量是一个挑战性问题。在搜索引擎中,为了处理海量数据检索,倒排索引是快速搜索技术的关键方法。文章把搜索引擎中的倒排索引方法和索引压缩算法应用到互联网网流信息检索中。通过实验测试和验证,在网流信息检索中,倒排索引以及索引压缩算法能够有效提高检索速度。     

基于uIP协议栈的嵌入式Web服务器的实现

为使数控系统具备网络访问功能,通过移植嵌入式TCP/IP协议栈—uIP,并且编写网络控制芯片驱动程序接口以及能实现HTTP协议的通用应用程序,使数控系统具备Web服务器的功能。用户可以使用PC接入Internet,通过标准浏览器远程监测数控系统的运行状态。     

流量调节防火墙的设计与实现

论述了防火墙技术可以对进出网络的数据进行控制,有效地对内部网络实施保护,而流量调节技术通过按优先级发送不同类别的信息量,达到改善网络服务质量的目的,文中将两种技术相结合,构建了某企业ＣＡＤ网络的防火墙ＷＱ－Ｆｉｒｅｗａｌｌ的安全系统,以求在获得安全的同时提高网络性能,在Ｌｉｎｕｘ系统上实现了加权优先级队列的防火墙,在对ＩＰ包进行过滤的同时,根据其ＩＰ地址、ＴＣＰ端口协议类型等信息,为它们分配了不同     

基于GPRS与CAN总线的水情智能监测系统的设计与实现

研究并开发了一种现场采用CAN总线进行数据采集,而利用GPRS进行数据传输的远程水位实时监测系统,该系统借助成熟的GPRS无线数据通信技术,结合TCP/IP通信协议,实现了CAN总线报文和IP协议的相互转换并通过GPRS无线网络和互联网传输CAN总线报文信息,进而对水库、河流等水情进行实时、可靠的监测.     

浅析基于网络协议的异常流量识别技术

本文提出构建基于网络协议的异常流量识别模型,结合网络协议分析、网络入侵检测技术等对网络数据层进行解析,通过对频繁IP 地址进行聚集发现网络中的异常流量IP 地址集合,统计出异常数据包。通过DDOS攻击实验结果分析得出,该模型具有较高的识别能力,并且在处理效率和计算强度方面都有很好的表现。     

使用SNMP协议对标准网络设备MIB库的访问

SNMP协议是 TCP/ IP协议集的一个组成部分。它对应于互联网协议集的应用层。使用 SNMP协议网络管理员能够从远程捕获和监控网络系统设备 (如网络交换机和路由器等 )的工作情况和状态。 SNMP协议的大部分被定义在 RFC 115 7和 RFC 12 12中。