Computer Networks and Local Area Network

1. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer Preparatory School of
Sfax
9 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
I- Computer Networks
I-1 – Presentation of a computer network:
Task1: Observe carefully these figures and describe them.
PIONEER
PREPARATORY
SCHOOL OF SFAX:
THE 9th
LEVEL
Lesson 2: INTRODUCING THE
LOCAL AREA NETWORK

2. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
10 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
* Terminals, and communication devices: iPad; iphone; smart phones; e-book; PSP;smart TV; …
**wires, cables, or a telecommunication system: are means of connection (physical links) through wires
or wireless connection.
 A network is a system of interconnectedcomputers and peripherals(suchas printers,scanners,
network cards, modems,routers, work stations); it can consist of as fewas two computers or millionsof
computers that are spread over a large geographical area connected(linked) bydifferenttypesof
physical links (forexample, optical fibercable, coaxial cable,telephone line,satellitetransmission,radio
waves,Wi-Fi,blue-tooth,infrared,etc.) allowingthe movement(the transfer, the transmission) or the
exchange of information betweenone centerto the other; and the sharing of hardware and software
resources.
 So, Some of the primary reasons ( the purposes ) for networkingPCsare as follows:
To provide servicesand Sharing files,Sharingprinters and other devicesinorder to reduce the
equipmentcosts,
Enabling commonadministration and security,
Supporting network applicationssuch as Electronic mail or videoconferencingorgroupware,etc, and
Sharing Databases services.
A computer network is a system of two or more ………………, terminals, and
communication devices* linked (……………..) by …………, cables, or a telecommunication
system** in order to …………….. software resources (data, files, programs, applications)
or hardware resources (printer or scanner, etc) and …………………….information. It
allows computers to ……………………. with each other. The purpose is to provide services
and to reduce distances and equipment costs.
Task 2: According to the last task, define a computer network.
Complete the following definition with words from this list:
information, exchange, computers,connected, communicate, wires, share
Observations

3. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
11 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Task 3:
According to the previous task and pictures, what are the components of a computer network?
A network computer is composed of:
 ..................................
 ..................................
 ..................................
 ..................................
 ..................................
I-2 – Types of computer networks:
A- Types of computer networks according to the geographic scale:
It depends on how much large is the area where it spans.
Task4: Fill in the blanks with the correct words.
Local Area Networks (LAN) is a network
that is confined to a relatively ………….. area.
It is generally limited to a geographic area
such as a lab, school, or building.
The defining characteristics of LANs include
their …………………… data transfer rates and
their technology is generally less expensive.
Ne tworks may be classifie d according to a wide varie ty of characte ristics su ch as :
 Scale , the me dium use d to transport the data, Topology, Communication protocols
use d, Organizational scope , e tc.

4. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
12 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
WAN (…………….. Area Network) spans a
……………….. physical distance.
A WAN is a geographically-dispersed
collection of ………… The data transfer rate is
quiet …..………. . The ……………......... is the
largest WAN, spanning the Earth. WANs are
more susceptible to errors due to the distances
data travels. They are more sophisticated and
complex than LANs. Their technology is
expensive.
Metropolitan Area Network or shortened by MAN. A
network in a city with high-speed data transfer,
which connects various locations such as campuses, offices,
government, and so on. MAN network is a composite of
several LANs Coverage of this MAN among 10 to 50 km,
MAN is the right network to build a network between
offices in the city of factories / establishments and
headquarters are within its range.
 There are other computer networks like: Campus Area Network (CAN), Home Area
Network (HAN), personal area Network (PAN)…
 The Data Transfer Rate (DTR) is the speed at which data can be transmitted between devices.
It’s often expressed in KB per second (KB/s) or MB/s. it depends on the distance, the quality of the
line, and the wire gauge.
Task 5: we want to make computers of the
following company to communicate and to
exchange data between them. How to do it?
…………………………………………………..
…………………………………………………..
Evaluation1: Deduce the differences between a LAN and a WAN? Complete the following table:
LAN WAN

5. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
13 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Geographic area
Network cabling (means of
connectivity)
Data Transfer Rate (DTR)
Evaluation2: Give examples of LAN and WAN networks?
LAN WAN
B- Typesof computernetworks according to the main typesof LAN
architectures:
C- Network topologies:
Types of computer networks according to their topology in a LAN
Activity 6: Focus on these computer networks. What are the differences between them?
 Wireless Networks
The Wireless LAN provides wireless network
communication over short distances using Wi-
Fi, radio waves or infrared signals.
Or combined with :
Wired networks
The Wired LAN is a network using wires like
cables to connect its components.

6. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
14 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Observation: The difference between the three computer networks is in their ………….. :
…………………………………………………………………………………………………
 We talk about …………………………...
What means Network Topology?
Activity 6: fill the blanks using these terms: nodes, the shape, Links, layout.
Activity 7: Try to search from the Internet the different kinds of network topologies.
There are many network topologies (used in LANs) such as:
 ………. topology: All devices are connected
to a ………………., called the ……. Bus
networks are relatively inexpensive and easy
to install for small networks.
……… topology: All devices are connected to
one another in the shape of a closed loop.
Ring topologies are relatively expensive and
…………….., but they offer …… data transfer
rate and can span ……… distances.

7. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
15 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Evaluation3: Enumerate the advantages and the disadvantages of each network topology?
Bus topology Ring topology Star topology Tree Topology
Advantages
Disadvantages
II- LAN devices:
 ………….. topology: All devices are
connected to central equipment: …………Star
networks are relatively easy to install and
manage. All data must pass through the hub.
 Tree Topology: integrate multiple startopologies
togetherontoa bus.In itssimplestform, only hub
devices connectdirectlytothe tree busandeach hub
functionsasthe "root" of a tree of devices.This
bus/starhybridapproachsupportsfuture expandability
of the networkmuchbetterthana bus (limitedinthe
numberof devicesdue tothe broadcast trafficit
generates) ora star (limitedbythe numberof hub
connectionpoints) alone.
Network Topology refers to ................................, or the ...................... of a computer
network. It determines how different ........................ and ....................... (Computer, printer,
modem…) are connected to each other in a network and how they communicate.

8. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
16 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Activity 8: Match each picture with its device’s description.
Device’s description Picture
Computers
Network card
(Ethernet card)
Cables (cable RJ45) : in the
case of a wired Network
Hub or switcher or router
Server (desktop computer)
WirelessNetwork cardWiredNetwork card

9. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
17 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
a) LAN Card:a piece of computer hardware
to allow the attached computer to
communicate by network using basic services
of a LAN.
a+………
1)
b) Hub: A device which connects the cables
from computers and other devices such as
printers in a LAN.
b+………
2)
c) Router: A device that connects to and
receives data from outer networks and sends
data only to network nodes c+……….
a) How to set up a Local Network?
To configure each computer on the net, just follow the following steps:
 go to Control Panel,
 double-click on "Network Connections",
 click the right mouse button on "Local Area Connection",
 choose properties,
 In the Windows LAN connection are displayed the various protocols installed. To share
files, play network games, use printer
 Each computer must be assigned an address called an IP address in order to communicate.
To do this you have to select the "Internet Protocol TCP / IP and click on “Properties”.
=> The allocation of IP addresses can be automatically or be set manually, which is
preferable for a small LAN.
Examples of IP address:
Computer N°: 1
IP Address: 192.168.0.1
Mask: 255.255.255.0
...
Computer N°: xxx
IP Address: 192.168.0.xxx
Mask: 255.255.255.0
Once the allocated IP address is done, simply close the window by clicking OK
(The DNS (domain name servers) will be left in automatic mode.
3)

10. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
18 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
b)Note:
The IP address, also known as an «Internet Protocol» or simply an "IP number", it
identifies a particular computer connected to a network. The IP address is a code made up of four
sets of numbers from 0 to 255, separated by three dots. For example "66.72.98.236" or
"216.239.115.148"
IV- Using basic services of a LAN
Activity 9: You have a folder that contains text documents, images and sound files. You want to
give a copy of this folder to your friends. Propose solutions to do it.
The local network is built to facilitate
sharing hardware and software resources:
 Sharing documents
 Sharing Printer
 Sharing messages
 Sharing screen
4.1- Sharing documents
Task 9: Page39: how to share a folder in a LAN?
 Select the folder or the file to share

11. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
19 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
 Click the right mouse button
 Choose the command “Sharing and Security”
 On the tab “Sharing” check the option “ share this folder on the network”
 Click on ok to confirm your action
4.2- Sharing Peripherals
(Printer)
Task 10: Each pupil wants to print his formatted text. Unfortunately, the laboratory is equipped with one
printer. Give a suitable solution to your friends.
 To share a printer installed in a computer
included in a local area network, you have to
follow these steps
1. Select the Printer that you want to share
2. Right click it and choose the printer
properties command,
3. Choose the option Sharing tab
4. Active the radio button Share this printer
5. and propose a name
6. Validate with ok.

12. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
20 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
4.3- Sending and receiving messages

13. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
21 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
Task 11: Do you remember the role of the following program? In which kind of network can use
it?
Task 12: Can you send and receive a message via a
local computer network?
Solution: ……………………………………
…………………………………………………
…………………………………………………
Task 13: Launch <Pop Messenger> and send “hello” to your friend.
 To send a message to my friend using
PopMessenger, I have to:

14. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
22 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
4.4- Sharing screen
Task 14: During your project,you have to prepare a PowerPoint presentation.Propose a method that
allows you to show your screen to one of your friends
Question:
Observe this illustration and fined other
operations that we can do with Pop
Messenger.
 With Pop Messenger, we can:
………………………………………………………………………………
…………………………………………………………………………
…………………………..

15. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
23 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
V- How to protect a LAN?
Task 16: What you need to protect your computer from cyber viruses?
Exercises
Task 1: Complete the definition of computer network with the following words:
Computers / Data transfer rate/ high/ connected/ small/ wide
In this chapter, I learned…
There exist two kinds of networks: Local Area Network LAN and Wide Area Network WAN.
 A computer network permits to share hardware and software Resources andensure
communication between computers.
 A computer network decrease costs and reduce distances.

16. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
24 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
A local network is a set of ……………., equipments and communications devices………….. together
in a ………… physical area (Society, Administration,…) via specific rules (protocol for
communication).
The ………………….. …..of a local network is often …………..
Task 2:
Create a new folder named “Course” underLocal Disk C:, and then share it.
Task 3:
Present 3 advantages of a computer network.
1. …………………………………………………………………………………………….
2. …………………………………………………………………………………………….
3. …………………………………………………………………………………………….
Task 4: Send to your friends the definition of a local network as a message (text or vocal) through the
local messaging software.
Task 5: Complete the definition of computer network with the following words:
Telecommunication / of communication / linked / exchange / computer
A …………………. network is a collection of terminals, computers and ……………………..systems.
These entities are ……………..and connected together through physical lines named lines
…………………… in order to transport and to ……………… data.
Task 6: Create a poster that you will stick in the proximity of your computer. It will be destined to all
students who want to use the computer network in order to accede to your files. This poster must
contain at least 3 advice and 3 obligations for using the content of your hard disk which is shared
to others.
Evaluation
Evaluation 1: Tick the correct answer
Questions True False I don’t
know
The Internet is a local network.
Data are exchanged in a local network with a high DTR.
We cannot share the printers in a local network.
In a local network, we can share folders.

17. 9th
level Unit 1 : Computer Networks: the LAN AY 2011/2012
Pioneer PreparatorySchool of
Sfax
25 Teacher: Mrs. IMEN TEKAYA BOUAZIZ
 If you have less than 7 correct answers, you must see again this chapter!
We cannot neither send nor receive messages in a LAN.
The use of a LAN is very expensive.
It’s possible to share the hard disk in a local network.
The term DTR means the data capacity of network.
The distance hasn’t any effect on a DTR of a network.
We can only send and receive messages in a local network.
When I use a computer of a local network, I can accede to all
connected computers and change configurations,move
files and folders as I like and block the access to certain
applications.
 To establish the connection of a LAN, you must have a network card
and wires. What do you need to establish a WAN connection?
 Some mobiles have the Bluetooth option. Can you explain this kind of
data transmission? Do you know some others?