2nd lecture
Presented by Dr. Sarah Mustafa Eljack

Based on their scale, networks can be classified
as :
Local Area Network (LAN)
 Metropolitan Area Network (MAN)
 Wide Area Network (WAN)
 Personal Area Network (PAN)

2

Local Area Network (LAN)


A computer network covering a small physical area,
like a home, office, or small group of buildings, such
as a school, or an airport.
Metropolitan Area Network (MAN)

A network that connects two or more local area
networks or campus area networks together but
does not extend beyond the boundaries of the
immediate town/city.
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
Wide Area Network (WAN)



A computer network that covers a broad area
The biggest one
Personal Area Network (PAN)


A computer network used for communication
among computer devices close to one person.
The smallest one
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WAN
MAN
AN
AN
MAN
AN
AN
…
WLAN
AN
AN
…
WLAN
WLAN
WLAN
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According to Network
Structure networks can be
classified as :


Peer–to–Peer Network..
Server Based Network.
Q: Define the client-server model, then classify networks
according to structure?
Sol:
in Client-Server model:
• Resources (H/W and S/W) are stored at the server.
• Users use simple machines (clients).
• Clients and servers are connected through a network.
• Clients can request any server resources then the server
replies clients requests.
Peer-to-Peer Network:

All network computers are identical, known as peers.

No servers.

No administrator for the network, each user controls his
computer.
Peer-to-Peer Network:


It is simple, smaller in size (10 or fewer machines),
less expensive than server based networks.
Each computer functions as client and server.
Server Based Network:
• it is the standard model (Opened in size).
• The network has servers
• Resources are centralized at the server, hence it can be
easily controlled.
• More expensive than peer-to-peer because Powerful
servers are required.
Q: what are the different server types?
Sol:
File server :
 Stores the shared files and backups.
Mail server :
Stores and forward e-mail messages between
clients.
Web server :
 Stores shared web pages.
o
Printer server :
 Allows different clients to use the same printer.
Shared
Printer
Print
Server
Print
Queue
Print
Job

Database server :
 stores Databases files used by network clients.

Proxy server :

exists between your network and other networks to
protect your network from the external attacks (acts as a
firewall).
LAN
switch
Proxy
server
External
Hosts
(other networks)
Peer-to-Peer networks
Server Based network
• all computers are identical.
No servers.
• Use powerful computers as
Servers, while the others are
clients.
has servers.•
Distributed
resources
Centralized
resources
Definition
Peer-to-Peer Network
Administration
Shared between network
users.
Server based Network
Centralized.
Peer-to-Peer networks
Shared
resources.


Distributed.
Difficult to be controlled.
Server Based network


Centralized.
Easily controlled.
Size
Has small size (usually 10
or fewer computers).
Has opened size.
Cost
Less expensive
More expensive
According to connectivity, there are two main types:

Wired Networks.

Wireless Networks.
Q: Classify computer networks according to connectivity?


Wired Networks:

Use wires to connect network computers.
Wireless Networks:

No wiring, connection is done using radio signals.

There are three different types:



Bluetooth network.
Wireless LAN.
Wireless WAN.
Wireless LAN:



A LAN connected through a radio signals.
Each computer has a radio modem connecting using
base station.
Base
Station
Antenna
Radio
Modem
•
Wireless WAN:
–
A wireless network covers a large geographical area.

Thanks for your attention
Any questions