计算机网络复习题库带题目.docx

1、计算机网络复习题库带题目一、 名词解释1.Computer network: A collection of autonomous computers interconnected by a single technology.2. client-server model :A network with two clients and one server.p4it is applicale when the client and serve are both in the same buiding , but also when they are far apart. The client-

2、server model involves requests and replies.3. Uses of networks : （a）Business Applications(商业应用)（c/s模型） (b) Home Applications(家庭应用)i. Access to remote information(访问远程信息)Newspapers on-line(在线报纸)Digital library(数字图书馆)ii. Person-to-person communication(个人之间的访问)Instant message(即时消息)Chat room(聊天室)Newsgro

3、ups(新闻组)iii. Interactive entertainment(交互式娱乐)Video on demand （视频点播）Game playing （游戏）iv. Electronic commerce(电子商务)Home shopping （在家购物）Access to financial institutions （访问金融机构）electronic flea markets （电子跳蚤市场）(c) Mobile Users(移动用户)(d) Social Issues(社会问题)4. two types of transmission technology (两种类型的传输技

4、术)(1)Broadcast links广播式Broadcast networksThe characteristic of Broadcast networks:Have a single communication channel Short message called packetsAn address field within the packetReceive the packetcheck its address field process or ignore (2)Point-to-point links点到点 Point-to-point links.点到点The opera

5、tion mode （操作模式）Unicasting (单播)：只有一个发送方和一个接收方的点对点传输模式A general rule（一般原则）：越小的地理位置局部化的网络使用广播传输模式大的网络使用点到点传输模式 5 LAN:they are privately-owned networks within a single buiding or campus of up to a few kilometers in size .(2)MAN: (A metropolitan area network) it covers a city.the best-known example of a

6、 MAN is the cable television network available in many cities . (3)WAN: (A wide area network )it spans a large geographical area , often a country or continent . (4)internetwork: A collection of interconnected networks6.The categories of wireless networks1. System interconnection (系统互连)2. Wireless L

7、ANs（无线LAN）3. Wireless WANs （无线WAN）7.IEEE 802 :Institute of Electrical and Electronics Engineers P76NumberTopic802.2|Logical link control802.3*Ethernet802.11*Wireless LANs802.15*Personal area networks(bluetooth)802.16*Broadband wireless8.protocol , protocol stack , network architecture (1)protocol:it

8、 is rules by which processes communicate (2)protocol stack:are typically based either on the OSI model or on the TCP/IP model .(3)network architecture:（陈晓雪的 Protocol is an agreement between the communicating parties on how communication is to proceed.A set of layers and protocols is called a network

9、 architecture.A list of protocols used by a certain system,one protocol per layer,is called a protocol stack.)二简答1.OSI reference model: （分为哪几个层次以及每个层次的含义） P39It is involved in seven layers。1 The Physical Layer. The Physical Layer is concerned with transmitting raw bits over a communication channel.（

10、在通信信道上传输原始数据位。）2 The Data Link Layer. The task of the Data Link Layer is to transform a raw transmission facility into a line that appears free of undetected transmission errors to the network layer.(数据链路层的主要任务是将一个原始的传输设备转变成一条逻辑的传输线路，在这条传输线路上，所有未检测出来的错误层次，也会反映到网络层上。)3 The Network Layer. The network

11、Layer controls the operation of the subnet.(网络层控制子网的运行过程。)4 The Transport Layer. The basic function of the transport layer is to accept data from above, split it up into smaller units if need be, pass these to the network layer, and ensure that the pieces all arrive correctly at the other end.(传输层的基

12、本功能是接受来自上一层的数据，并且在必要的时候把这些数据分割成小的单元，然后把数据单元传递给网络层，并且确保这些数据片段都能够正确的到达另一端。)5 The Session Layer. The session layer allows users on different machines to establish sessions between them.(会话层允许不同机器上的用户之间建立会话。)6 The Application Layer. The application layer contains a variety of protocols that are commonly

13、 needed by users.(应用层包含了各种各样的协议。)7 The Presentation Layer. The presentation layer is concerned with the syntax and semantics of the semantics of the information transmitted.(所传递的信息的语法和语意。)2. TCP/IP model:The ability to connect multiple networks in a seamless way was one of the major design goals fro

14、m the very beging. This architecture later become known as the TCP/IP reference model. It is involved in four layers.（1）The Internet Layer. The internet layer is the linchpin that holds the whole architecture together.(将整体网络体系贯穿在一起。)（2）The Transport Layer. The transport layer allows peer entities on

15、 the source and destination hosts to carry on a conversation.(允许源和目标主机上的对等体之间可以进行会话。)（3）The Application Layer. It contains all the higher-level protocols.(它包含了所有的高层协议)（4）The Host-to-Network Layer. It points out that the host has to connect to the network using some protocol so it can send IP packets

16、 to it.(它指出主机必须通过某个协议连接到网络上，以便可以将分组发送到网络上。)三、 Problems: 18,19（P82）18. OSI 的哪一层分别处理以下问题？把传输的比特流划分为帧数据链路层决定使用哪条路径通过子网网络层.19.question：If the unit exchange at the data link level is called a frame and the exchanged at the network level is called a packet ,do frames encapsulate packet or do packets encap

17、sulate frame ? 答：帧封装包。 当一个包到达数据链路层时，整个数据包，包括包头、数据及全部内容，都用作帧的数据区。或者说，将整个包放进一个信封(帧)里面，( 如果能装入的话)。第二章一、名词解释(一)、optical transmission system(光传输系统)： has three key components the light source the transmission medium the detector（二）、 wireless transmission 1、The Electromagnetic Spectrum（电磁波谱）2、*Radio Transm

18、ission : radio is easy to generate , can travel long distances , and penetrate buidings easy .（无线电波很容易产生，也可以传输很长的距离，并且易于穿透建筑物。） 3. Microwave Transmission （微波传输） (1)about 100 MHz , the wave travel in nearly straight lines and can therefore be narrowly focused . （在100MHZ以内，电波几乎按直线传播） (2) Microwaves do

19、 not pass through buildings well.（微波不能很好的穿透建筑物） (3)disadvantage : multipath fading （多路衰减），Absorbted by water（微波可以被水吸收） (4)it has two signficent advantages over fibera .the main one is that no right of way is needed .b .microwave is also relatively inexpensive . 4. Infrared and Millimeter Wave (uede

20、for short-range communication . they are directional , cheap , easy to buid and they do not pass through solid objict ) 5. Lightwave Transmission a) The lasers strength, a very narrow beam, is also its weakness here b) A disadvantage is that laser beams cannot penetrate rain or thick fog, but they n

21、ormally work well on sunny days.c) Convection currents can interfere with laser communication systems. （三）.ISM（Industrial, Scientific, Medical ） 1. Industrial, Scientific, Medical（工业的、科学的、医药的） 2. allocating frequencies is to not allocate them at all （频段的位置不同） 3. Just let everyone transmit at will bu

22、t regulate the power used so that stations have such a short range they do not interfere with each other（四）、telephone system consists of three major components 1. Local loops : analog twisted pairs going into houses and businesses(本地回路，双绞线进入家庭和业务部门，模拟信号) 2. Trunks : digital fiber optics connecting t

23、he switching offices（干线，通过光纤将交换局连接起来，数字信号） 3. Switching offices : where calls are moved from one trunk to another（交换局，电话呼叫从一条干线接入另一条干线）（五）、1、full duplex ：all modern modems allow traffic in both directions at the same time(by using different frequencies for different directions). A connection that al

24、lows traffic in both directions sumultaneously is called full duplex. A two-lane road is full duplex 2. half duplex : A connection that allows traffic either way, but only one way at a time is called half duplex. A single railroad track is half duplex. 3. simplex : A connection that allows traffic o

25、nly one way is called simplex. (六). Multiplexing:FDM and TDM（P137） 1. Multiplexing(multiplexing many conversations over a single physical trunk). （用于一条物理干线上尽可能的并发传输多个会话） 2.FDM (Frequency Division Multiplexing)（频分多路复用）3.TDM (Time Division Multiplexing) （时分多路复用）(七)、switching : circuit switching and pa

26、cket switching（交换，电路交换和报文交换）（P147、P150）1. The difference between Packet Switching and Circuit Switching circuit switching requires that a circuit be set up end to end before communication begins. Packet switching does not require any advance setup. Packet switching is more fault tolerant than circui

27、t switching. Setting up a path in advance also opens up the possibility of reserving bandwidth in advance. congestion can occur at different times with circuit switching (at setup time) and packet Packet switching does not waste bandwidth and thus is more efficient Packet switching uses store-and-fo

28、rward transmission. circuit switching is completely transparent. the charging algorithm 2. A comparison of circuit-switched and packet-switched networks3. message switching: store-and-forward network 二、简答1、Modulation (three kinds of Modulation)?陈晓雪的答案：There are three basic types of modulation: ampli

29、tude modulation (AM) varies the voltage; frequency modulation (FM) varies the frequency, and phase modulation (PM) varies the angle of the wave (see amplitude modulation, frequency modulation and phase modulation). In quadrature amplitude modulation (QAM), both the amplitude and phase of the carrier

30、 are modified (see QAM)。第三章一、简答（一）、The function of data link layer (数据链路层的功能) 答案：The specific functions it can carry out 1. Providing a well-defined service interface to the network layer.2. Dealing with transmission errors.3. Regulating the flow of data so that slow receivers are not swamped by fas

31、t senders.（二）、four methods of framing （四种成帧方法）P188P1901. Character count. 字符计数法。 2. Flag bytes with byte stuffing. 含字节填充的分界符法。3. Starting and ending flags, with bit stuffing. 含位填充的分界标志法。4. Physical layer coding violations 物理层编码违例法。（三）、Hamming code 计算题 P195（四）、CRC 计算题 P197P198 (五)、Sliding window protocols （滑动窗口协议）？P211-P2131、Data frame and acknowledgement frame（1）two separate physical circuits（2）use the same circuit for data in both directions（3)Piggybacking (4)Acknowledgements can be hooked onto the next outgoing data frame 2、sending windowthe sender maintains a set of sequence number