新编计算机专业英语chapter 08

1、Chapter 8 Computer Network 新编计算机专业英语IntroductionIn this chapter, we present an overview of computer network,learn different kinds of networks ,and know the design and organization of these networks . It is essential to understand the concept of computer network, the inpact of protocol hierarchies, d

2、istinguish between different types of networks, and hardware of computer networks. Section A. Network Software The subject of computer network covers many different kinds of networks, large and small, well known and less well known. 1. Example networks The Internet The Internet was launched in 1969

3、when United States funded a project that developed a national computer network called the Advanced Research Projects Agency Network (ARPANET). The Internet is not a network, but a vast collection of different networks that use certain common protocols and provide certain common services. What does i

4、t actually mean to be on the Internet? The definition is that a machine is on the Internet if it runs the TCP/IP protocol stack, has an IP address, and can send IP packets to all the other machines on the Internet. What about those personal computers can access the Internet by using a modem or a NIC

5、 ? Ethernetthe most popular LAN is Ethernet Architecture of the original Ethernet Wireless LANs The standard :802.11(WiFi ) Base station Ad hoc networking 2. Protocol Hierarchies A set of layers and protocols is called a network architecture two important network architectures the OSI reference mode

6、l it deals with connecting open systemsthat is, systems that are open for communication with other systems. the TCP/IP reference model It has the ability to connect multiple networks in a seamless way. IP (Internet Protocol). comparison of the OSI reference model and the TCP/IP reference model3. Typ

7、es of networks Personal area network (PAN) Local Area Network (LAN)Campus Area Network (CAN)Metropolitan Area Network (MAN)Wide Area Network (WAN)Global Area Network (GAN)Section B Network Hardware Physical communication channel media can be used for the actual transmission: guided media and unguide

8、d media . Twisted pair Coaxial cable Fiber optic cable Microwaves 2. Basic hardware components Network Interface Cards A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. Repeaters Hubs Br

9、idges SwitchesRoutersSection C Review & ReadingReview try to solve these problems(1) In the future, when everyone has a home terminal connected to a computer network, instant public referendums on important pending legislation will become possible. Ultimately, existing legislatures could be eliminat

10、ed, to let the will of the people be expressed directly. The positive aspects of such a direct democracy are fairly obvious; discuss some of the negative aspects.(2) Which of the OSI layers handles each of the following:(a) Dividing the transmitted bit stream into frames.(b) Determining which route

11、through the subnet to use.(3) List two ways in which the OSI reference model and the TCP/IP reference model are the same. Now list two ways in which they differ.(4) What is the main difference between TCP and UDP?(5) The ping program allows you to send a test packet to a given location and see how l

12、ong it takes to get there and back. Try using ping to see how long it takes to get from your location to several known locations. From thes data, plot the one-way transit time over the Internet as a function of distance.(6) The Internet is made up of a large number of networks. Their arrangement det

13、ermines the topology of the Internet. A considerable amount of information about the Internet topology is available on line. Use a search engine to find out more about the Internet topology and write a short report summarizing your findings. 2. Supplimentary Reading - Father of Fiber-Optics Wins Nob

14、el Prize Press Release of The Nobel Prize in Physics 2009 6 October 2009Professor Charles Kao The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2009 with one half to Charles K. Kao Standard Telecommunication Laboratories, Harlow, UK, and Chinese University of

15、Hong Kong for groundbreaking achievements concerning the transmission of light in fibers for optical communicationthe then young scientist Charles Kao doing an early experiment on optical fibre at the Standard Telecommunications Laboratory at Harlow, United Kingdom. 3. Grammer: 长句的理解和翻译科技英语中为了表述一个复杂

16、概念，使之逻辑严密，结构紧凑，科技文章中往往出现许多长句。例1 Those functions that describe how a computer software reacts to mechanical design, called application functions, are more often important to the engineer in engineering applications such as analysis, calculation, and simulation in connection with mechanical design bec

17、ause he wishes to know how they will work in use to which he wants to apply them. 例2 Only by studying such cases of human intelligence with all the details and by comparing the results of exact investigation with the solutions of AI(Artificial Intelligence) usually given in the elementary books on c

18、omputer science can a computer engineer acquire a thorough understanding of theory and method in AI, develop intelligent computer programs that work in a human like way, and apply them to solving more complex and difficult problems that present computer cant. 练习（1）Each chemical element has its number and fixed position in the table, and from this it became possible to predict its behavior: how it would react with other elements, what kind of compounds it would form, and what sort of physical properties it would have. 请分析下列句