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3. COMPUTER NETWORK
“A computer network often simply referred to as a network, is a collection of computers and
devices interconnected by communication channels that facilitate communications and allows
sharing of resources and information among interconnected devices.”
 NEED OF COMPUTER NETWORK
We need computer networks for the following purposes:
 File Sharing.
 Resource Sharing.
 Remote Access.
 Data Protection.
 Communication and Collaboration.
 CLASSIFICATION OF NETWORKS
Networks may be classified according to a wide variety of characteristics such as medium used
to transport data, communication protocol used, scale, topology, organizational scope, etc.
TYPES OF COMPUTER NETWORK
There are three types of network. These are:
 Local Area Network.
 Metropolitan Area Network.
 Wide Area Network.
 Personal Area Network.
.

4. Local Area Network (LAN)
“A Local Area Network is a group of computers and a group of computers and associated
devices that share a common communication line or wireless link.”
A LAN is operated within a limited physical area, such as at home, school, a single building or
several buildings. Simplest form of LAN is to connect to computers and a printer in someone’s
home office. In general, a given LAN will use only one type of transmission medium.
A network which consists of less than 500 interconnected devices across several buildings, is
still recognized as LAN. LAN’s can be either wired or wireless. Early LANs had data rates in the
4-6 megabits per second (Mbps) range. Today, however, speeds are normally 100 or 1000 Mbps.
Wireless LANs are the newest evolution in LAN technology.
Example: A common example of LAN, found in many business environments, links a work
group of task-related computers by establishing client-server model.
Advantages of LAN
 Speed.
 Cost.
 Security.
 E-mail.
 Resource Sharing.
Disadvantages of LAN
 Expensive to Install.
 Requires Administrative Time.
 File Server May Fail.
 Cables May Break.

5. Metropolitan Area Network (MAN)
“A Metropolitan Area Network is a network that interconnects users with computer resources in
a geographical area or region larger than that covered by even a large Local Area Network but
smaller than the area covered by Wide Area Network (WAN).”
Metropolitan’ -describes important cities like Lahore, Karachi, Islamabad etc. So, one can say it
covers the area inside a town or a city. Companies with several branches within the Lahore use a
MAN. A MAN might be owned and operated by a single organization, but it usually will be used
by many individuals and organizations.
It is also used to mean the interconnection of several Local Area Networks by bridging them
with back bone lines. In a city, MAN ranges within 100 km.
Example: A good example of MAN is the part of the telephone company network that can
provide a high-speed DSL line to the customer.
Advantages of MAN
 Bandwidth of connecting links
 Cost of sharing is quite cheap and fast throughout the MANs
Disadvantages of MAN
 It is very expensive for the setting part.
 It has to be well-planned and well-organized before setting the system because MANs
need to go along with the phone network of that particular area.

6. Wide Area Network (WAN)
“A Wide Area Network is a communication network that makes use of existing technology to
connect local computer networks into a larger working network that may cover both national
and international networks.”
WAN is the group of MANs or LANs or the mixture of both networks. It covers the largest
distances such as states, countries, or continents. It can be as complex as the backbone and as
simple as dial-up line. We normally refer to the first as a switched WAN and to the second as
point-to-point WAN. The switched WAN connects the end system, which usually comprise a
router (connecting device) that connects to another LAN or WAN. The point-to-point WAN is
normally a line leased from telephone or a cable TV provider that connects a home computer or a
small LAN to an internet service provider (ISP).
Example: The type mentioned above is used to provide Internet access which is the largest WAN
in the world.
Advantages of WAN
 Communication Facility.
 Remote Data Entry.
 Centralized Data.
 Entertainment.
Disadvantages of WAN
 Hardware, Software and Setup Costs.
 Hardware and Software Management Costs.
 Data Security Concerns.
 Failure of Server.

7. Personal Area Network (PAN)
“A PAN is a network that is used for communicating among computers and computer devices
(including telephones) in close proximity of around a few meters within a room.”
The devices may or may not belong to the person in question. The reach of a PAN is typically a
few meters (30 feet). The devices may include portable computer, smart phones, digital cameras,
portable digital media player and printers etc. PAN enables devices to communicate and share
data. PAN may use wire or wireless technology.
Example: A PAN can be used to sync. Data from a handheld device to a desktop computer, move
data wirelessly to a printer, or transmit data from a smartphone to a wireless headset. Wireless
PANs are more common than wired PANs and use Bluetooth or Wi-Fi technology to connect
devices.
Advantages of PAN
 Security.
 Wearable Computing.
Disadvantages of PAN
 Health Issue.
 Expensive.
PAN

8. CONTRAST BETWEEN LAN, MAN, WAN, PAN
Reference
 www.assignmenthelp.net
 www.kingofnetworking.weebly.com
 www.bbc.co.uk
 Book IIT