《计算机网络简介》PPT课件.ppt

专业英语,Chapter 11 Introduction to Computer Network,专业英语,Technical Terms and Proper Names Analog and digital 模拟和数字 Frequency 频率 Spectrum 频谱 bandwidth 带宽 Bit rate 比特率 baud rate 波特率 Simplex 单工 half-duplex半双工 Full-duplex 全双工 star network 星型网络 bus network 总线型网络 ring network 环形网络 Hierarchical network 分层网络 client/server network system 客户机/服务器网络系统 Peer-to-peer network system 对等网络系统 Local Area Network(LAN) 局域网 Metropolitan Area Network(MAN) 城域网 Wide Area Network （WAN）广域网 Internet 因特网 physical layer 物理层 OSI reference model OSI（开发系统互联）参考模型,Technical Terms and Proper Names Data link layer 数据链路层 network layer 网络层 Transport layer 传输层 session layer 会话层 Presentation layer 表示层 application layer 应用层 TCP/IP reference model TCP/IP参考模型 Host-to-network layer 主机-网络层 Internet layer 网际层 IP 互联网协议 TCP 传输控制协议 UDP 用户数据报协议 ISO (International Standards Organization)国际标准化组织 ITU-T (International Telecommunications Union) 国际电信联盟电信标准委员会 ANSI (American National Standards Institute) 美国国家标准协会,专业英语,11.1 Data Communication,Both data and the signals that represent them can take either analog or digital form. Analog refers to something that is continuous- a set of specific points of data and all possible points between. Digital refers to something that is discrete.,数据和表示数据的信号都可以采取模拟形式或是数字形式。模拟意味着是连续的量- 一组具体的数据点和它们之间所有可能的点的数据。数字的指的是离散的事务。,专业英语,11.3 Data Communication,Remote batch is the term used for the way in which data communications technology is used geographically to separate the input and/or output of data from the computer on which they are processed in batch mode.,远程批处理是这样一个术语，数据通信技术方式按照地理位置从以批处理模式处理的计算机上将数据的输入/输出分离出来。,专业英语,11.3 Data Communication,How information is encoded depends on its original format and on the format used by the communication hardware.,信息的编码方式取决于其原始的格式和通信硬件采用的格式。,专业英语,11.3 Data Communication,As is known, information can be of two types, digital or analog, and signals can be two types, also digital or analog.,众所周知，信息可能有两种类型，数字或模拟的。而信号也可以是数字或是模拟的。,专业英语,11.3 Data Communication,In a half-duplex transmission, the entire capacity of a channel is taken over by whichever of the two devices is transmitting at the time.,在半双工传输中，无论哪一方开始传输，都使用信道的的整个带宽。,专业英语,11.2 Introduction to Computer Networks,The concept of the “computer center” as a room with a large computer to which users bring their work for processing is now totally obsolete.,用户带着他们的工作去一个配备有很大计算机的房间进行上机处理的“计算机中心”的概念现在完全过时了。,专业英语,11.2 Introduction to Computer Networks,A system with one control unit and many slaves is not a network; nor is a large computer with remote printers and terminals.,一台主控机和多台从属机的系统不是一个网络。同样地，一台带有远程打印机和终端的大的计算机也不是网络。,专业英语,11.3 Application of Computer Networks,Computer networks have become an indispensable part of business, industry and entertainment in the short time they have been around.,计算机网络出现不久，就成为商务、工业、娱乐中必不可少的一部分。,专业英语,11.3 Application of Computer Networks,Two applications that use networks to provide essential services are computer-assisted design (CAD) and computer-assisted manufacturing(CAM), both of which allow multiple users to work on a project simultaneously.,使用网络来提供重要业务的两种应用是计算机辅助设计（CAD）和计算机辅助制造（CAM），两者都允许多名用户同时工作于一个项目上。,专业英语,11.4 Categories of Network,People connected to one network often want to communicate with people attached to a different one. This desire requires connecting together different, and frequently incompatible networks, sometimes by using machines called gateways to make the connection and provide the necessary translation, both in terms of hardware and software.,链接到一个网络上的用户经常需要和链接到另一个网络上的用户进行通信。这就需要连接不同的、而且往往是不兼容的网络，有时候通过使用被称为网关的机器来完成连接，并提供必要的硬件上和软件上的转换。,专业英语,11.5 OSI and TCP/IP Reference Model,The number of layers should be large enough t