Unit One
Network Fundamentals
网络基础

Lesson 1 Computer Networking

Computer networking is a linking of the network devices and computers with each other to provide data communications and share network resources such as printer, scanner, modem, CD/DVD and internet access.A computer network can be interconnected with the UTP/STP cables, coaxial cables, and fiber optics and wireless devices through the radio waves． Today, no business can work effectively without the data communications within the organization． A network can be designed by different layouts known as topologies.

The common topologies include star, tree, mesh, hybrid and ring． Star topology is the most common topology in Ethernet-based local area network.There are specialized rules and standards, the network devices communicate with each other based on these standards． One of these specialized standards and agree-up ways is known as protocols, TCP/IP is the protocol suite that contains multiple communication protocols such as TCP, IP, SMTP, FTP, DHCP, LDAP, PPP, Telnet and many others.TCP/IP works together and it is the most common communication protocol for LAN, WAN and Internet． The communications on the Internet is based on the IP address, which is a part of the TCP/IP stacks． No computers on the Internet or in the LAN/MAN/WAN can communicate without a unique IP address.

Networking and data communications provide the flexibility, easy way of work and communications with each other, and today every kind of business in the world, which involves more than one computer, but requires a computer network.A network can be set up by using the following things．

● Computers with Windows/Linux operating system installed． Every computer requires a unique LAN card, which should be properly installed and configured． Ethernet cable with the RJ-45 connectors at both ends．

● A Router/Switch or hub． The other devices are bridges, transceivers, terminal servers and gateways，they can be set up according to your requirements． There are three main types of the computer networks i．e． LAN, MAN, WAN． Each network is either a peer-to-peer or client/server network． In a client/server network model, a centralized domain controller is used to control all the computer networks． It provides the services

to the clients like logon authentication, printer access, scanner access, centralized data storage, user management, resources management, DHCP, DNS, FTP and internet access.

To communicate with the other computer, each computer should support the same protocol and the TCP/IP is the most commonly used protocol in a computer network． Internetwork is a type of computer network that connects the two or more different networks． There are three main types of internetworks i．e． Intranet, Extranet and Internet.

New Words and Expressions

networking n． 联网，网络

link n． 连接，链接

device n． 设备

communication n． 通信，通信，交流

resource n． 资源

printer n． 打印机

scanner n． 扫描仪

modem n． 调制解调器

access n． 访问，访问权限v． 访问，接入，使用

interconnect v． 使互相连接

cable n． 电缆

coaxial adj． 同轴的

fiber n． 纤维，光纤

optics n． 光学

wireless adj． 无线的

effectively adv． 有效地

layout n． 布局，设计，安排

topology n． 拓扑结构

star n． 星，恒星

hub n． 集线器

mesh n． 网状物；网，网格

hybrid n． 混合，混合物，杂种

ring n． 环，环形物

specialize v． 使专业化，使专门化

specialized adj． 专门的，专业的

protocol n． 协议

suite n． 组件，族，群，套房

multiple adj． 多重的，多种的，多样的

Telnet n． 远程登录协议

stack n． 堆栈

unique adj． 唯一的，独特的

flexibility n． 灵活性

involve v． 包含，涉及，使陷于

install v． 安装

configure v． 配置

Ethernet n． 以太网

connector n． 连接器

router n． 路由器

switch n． 交换机，交换器，开关

bridge n． 网桥

transceiver n． 收发器

terminal adj． 终端的n． 终端机

server n． 服务器

gateway n． 网关

centralized adj． 集中的

domain n． 域，域名

controller n． 控制器

logon n． 注册，登录

authentication n． 认证，验证

storage n． 存储

Intranet n． 内联网

Extranet n． 外联网

radio wave声波

coaxial cable同轴电缆

operating system操作系统

Abbreviations（缩写）

CD（Compact Disk）光盘

DVD（Digital Video Disk）数字化视频光盘

UTP（Unshielded Twisted Paired）非屏蔽双绞线

STP（Shielded Twisted Paired）屏蔽双绞线

TCP（Transmission Control Protocol）传输控制协议

IP（Internet Protocol）互联网协议

SMTP（SimpleMailTransferProtocol）简单邮件传输协议

FTP（File Transfer Protocol）文件传输协议

DHCP（Dynamic Host Configuration Protocol）动态主机配置协议

LDAP（Lightweight Directory Access Protocol）轻量级目录访问协议

PPP（Point-to-Point Protocol）点对点通信协议

LAN（Local Area Network）局域网

WAN（Wide Area Network）广域网

DNS（Domain Name Service）域名服务

Exercises

I. Translate the following Chinese terms into English.

1． 打印机

2． 扫描仪

3． 网络

4． 调制解调器

5． 接口

6． 电缆

7． 光纤

8． 局域网

9． 广域网

10． 服务器

11． 安装

12． 配置

13． 路由器

14． 集线器

15． 交换机

II. Translate the following English terms into Chinese.

1． Transceiver

2． Intranet

3． Extranet

4． Operating System

5． Bridge

6． Topology

7． DNS

8． DHCP

9． TCP

10． FTP

11． Gateway

12． Ethernet

13． Authentication

14． Controller

15． Connector

III. Choose the best answer from the four choices according to the passage.

1． What functions does computer networking have?

A． provide data communications

B． share network resources

C． serve the businesses effectively

D． All of the above

2． With which methods can a computer network be interconnected?

A． modem

B． scanner

C． UTP/STP cable

D． mouse

3． Which is the most common topology in Ethernet-based local area network?

A． hub topology

B． mesh topology

C． star topology

D． ring topology

4． Which of the following does not belong to TCP/IP suite?

A． FTP

B． DVD

C． Telnet

D． DHCP

5． Which of the following statements is not true?

A． No computer on the internet can communicate without a unique IP address．

B． TCP/IP is the most common communication protocol for LAN, WAN and internet．

C． Every computer requires a unique LAN card, which should be properly installed and configured．

D． There are two main types of computer network．

IV. Translate the following sentences into Chinese.

1． Today, no business can work effectively without the data communications within the organization．

2． TCP/IP works together and it is the most common communication protocol for LAN, WAN and Internet．

3． Every computer requires a unique LAN card, which should be properly installed and configured．

4． In a topology, there are specialized rules and standards and based on these standards, the devices communicate with each other．

5． To communicate with the other computer, each computer should support the same protocol．

6． Internetwork is a type of computer network that connects the two or more different networks．

7． The communications on the Internet is based on the IP address, which is a part of the TCP/IP stack．

8． TCP/IP is the protocol suite that contains multiple communication protocols．

参考译文

计算机网络

计算机网络是指网络设备和计算机彼此连接，以提供数据通信和共享网络资源，如打印机、扫描仪、调制解调器、CD/DVD及互联网访问。计算机网络可被UTP/STP电缆、同轴电缆、光纤或无线设备通过无线电波互相连接。如今，若企业组织内部没有数据通信，那么它就无法有效地工作。网络可以设计成不同布局方式，称为拓扑结构。

常见的拓扑结构包括星状拓扑、树状拓扑、网状拓扑、混合拓扑和环状拓扑。在基于以太网的局域网中，星状拓扑是最常见的拓扑。它有专门的规则和标准，基于这些标准网络设备才能互相通信。其中，人们以某些方式达成一致并被认同的标准称为协议。TCP/IP协议族，含有多种通信协议，如TCP、IP、SMTP、FTP、DHCP、LDAP、PPP、Telnet和很多其他的协议。TCP/IP共同协作，它是局域网、广域网和互联网中最常见的通信协议。互联网上的通信是基于IP地址的，它是TCP/IP协议中的一部分。在互联网、局域网、城域网和广域网中，没有计算机能够在没有单独的IP地址的情况下进行通信。

网络和数据通信提供了灵活性、简单的工作方式和互相沟通方式，今天世界上的每个企业涉及的不只是一台计算机，而是需要一个计算机网络。通过使用以下设备可建立起一个网络。

● 安装了Windows/Linux操作系统的计算机。每一台计算机需要一个独立的LAN卡，LAN卡应该被正确地安装和配置。两端都要用RJ-45连接器连接。

● 一台路由器/交换机或集线器。根据需求可以安装其他设备，如网桥、收发器、终端服务器和网关。有三种主要类型的计算机网络——LAN，MAN，WAN，每一种网络要么是端到端网络，要么是客户/服务器网络。在客户机/服务器网络模型中，一个集中的域控制器是用来控制所有的计算机网络的，它为客户提供像登录验证、打印机访问权限、扫描仪访问权限、集中数据存储、用户管理、资源管理、动态主机配置协议、域名服务、文件传输协议，以及互联网接入等服务。

要想与其他的计算机通信，每台计算机应该支持相同的协议。TCP/IP是在计算机网络中最常用的协议。互联网络是一种计算机网络，连接着两种或两种以上不同的网络。在互联网络中有三种主要类型，即内联网、外联网和互联网。

Crazy Combat（疯狂实战）

1． In an Ethernet network, under what two scenarios can devices transmit? (Choose two．)

A． when they receive a special token

B． when there is a carrier

C． when they detect no other devices are sending

D． when the medium is idle

E． when the server grants access

2． When a host transmits data across a network to another host which process does the data go through?

A． standardization

B． conversion

C． encapsulation

D． synchronization

3． The network administrator has asked you to check the status of the workstation’ IP stack by pinging the loopback address． Which address would you ping to perform this task?

A． 10．1．1．1

B． 127．0．0．1

C． 192．168．0．1

D． 239．1．1．1

4． Workstation A has been assigned an IP address of 192．0．2．24/28． Workstation B has been assigned an IP address of 192．0．2．100/28． The two workstations are connected with a straight-through cable． Attempts to ping between the hosts are unsuccessful． What two things can be done to allow communications between the hosts? (Choose two．)

A． Replace the straight-through cable with a crossover cable．

B． Change the subnet mask of the hosts to /25．

C． Change the subnet mask of the hosts to /26．

D． Change the address of Workstation A to 192．0．2．15．

E． Change the address of Workstation B to 192．0．2．111．

5． Which protocols are found in the network layer of the OSI reference model and are responsible for path determination and traffic switching?

A． LAN

B． routing

C． WAN

D． network

6． What are three valid reasons to assign ports to VLANs on a switch? (Choose three．)

A． to make VTP easier to implement

B． to isolate broadcast traffic

C． to increase the size of the collision domain

D． to allow more devices to connect to the network

E． to logically group hosts according to function

F． to increase network security

7． A network administrator issues the ping 192．168．2．5 command and successfully tests connectivity to a host that has been newly connected to the network． Which protocols were used during the test?(Choose two．)

A． ARP

B． CDP

C． DHCP

D． DNS

E． ICMP

8． Refer to the exhibit． Host A is to send data to Host B． How will Router1 handle the data frame received from Host A? (Choose three．)

A． Router1 will strip off the source MAC address and replace it with the MAC address on the forwarding FastEthernet interface．

B． Router1 will strip off the source IP address and replace it with the IP address on the

forwarding FastEthernet interface．

C． Router1 will strip off the destination MAC address and replace it with the MAC address of Host B．

D． Router1 will strip off the destination IP address and replace it with the IP address of Host B．

E． Router1 will forward the data frame out interface FastEthernet0/1．

F． Router1 will forward the data frame out interface FastEthernet0/2．

9． Refer to the exhibit． What will Router1 do when it receives the data frame shown? (Choose three．)

A． Router1 will strip off the source MAC address and replace it with the MAC address 0000．0c36．6965．

B． Router1 will strip off the source IP address and replace it with the IP address 192．168．40．1．

C． Router1 will strip off the destination MAC address and replace it with the MAC address 0000．0c07．4320．

D． Router1 will strip off the destination IP address and replace it with the IP address of 192．168．40．1．

E． Router1 will forward the data packet out interface FastEthernet0/1．

F． Router1 will forward the data packet out interface FastEthernet0/2．

10． Refer to the exhibit． Host A pings Host B． What source MAC address and source IP address are contained in the frame as the frame leaves R2 destined for host B?

A． abcd．abcd．a001

B． abcd．abcd．b002

C． abcd．abcd．c003

D． 10．2．0．15

E． 10．0．64．1

F． 10．0．128．15

参考答案

1.CD 2.C 3.B 4.AB 5.B 6.BEF 7.AE 8.ACF 9.ACF 10.BD