COMPUTER

NETWORKS

What is Network?

• A network consists of two or more computers

that are linked in order to share resources (such

as printers and CDs), exchange files, or allow

electronic communications.

• The computers on a network may be linked

through cables, telephone lines, radio waves,

satellites, or infrared light beams.

Different Types of Networks

• Depending upon the geographical area covered

by a network, it is classified as:

– Local Area Network (LAN)

– Metropolitan Area Network (MAN)

– Wide Area Network (WAN)

– Personal Area Network (PAN)

Local Area Network (LAN)

A LAN is a network that is used for communicating among

computer devices, usually within an office building or home.

• LAN’s enable the sharing of resources such as files or

hardware devices that may be needed by multiple users

•

• Is limited in size, typically spanning a few hundred meters,

and no more than a mile

• Is fast, with speeds from 10 Mbps to 10 Gbps

• Requires little wiring, typically a single cable connecting to

each device

• Has lower cost compared to MAN’s or WAN’s

LAN’s can be either wired or wireless. Twisted pair,

coax or fibre optic cable can be used in wired LAN’s.

• Every LAN uses a protocol – a set of rules that governs

how packets are configured and transmitted.

• Nodes in a LAN are linked together with a certain

topology. These topologies include:

– Bus

– Ring

– Star

• LANs are capable of very high transmission rates (100s

Mb/s to G b/s).

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

Metropolitan Area Network (MAN)

• A metropolitan area network (MAN) is a large

computer network that usually spans a city or a

large campus.

• A MAN is optimized for a larger geographical

area than a LAN, ranging from several blocks of

buildings to entire cities.

• A MAN might be owned and operated by a

single organization, but it usually will be used

by many individuals and organizations

Metropolitan Area Network (MAN)

• A MAN often acts as a high speed network to

allow sharing of regional resources.

• A MAN typically covers an area of between 5

and 50 km diameter.

• Examples of MAN: Telephone company

network that provides a high speed DSL to

customers and cable TV network.

Wide Area Network (WAN)

• WAN covers a large geographic area such as

country, continent or even whole of the world.

• A WAN is two or more LANs connected

together. The LANs can be many miles apart.

• To cover great distances, WANs may transmit

data over leased high-speed phone lines or

wireless links such as satellites.

• Multiple LANs can be connected together

using devices such as bridges, routers, or

gateways, which enable them to share data.

• The world's most popular WAN is the Internet

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

• It can be used for communicating between the

devices themselves, or for connecting to a larger

network such as the internet.

• PAN’s can be wired or wireless

• A personal area network (PAN) is a computer

network used for communication among

computer devices, including telephones and

personal digital assistants, in proximity to an

individual's body.

• The devices may or may not belong to the

person in question. The reach of a PAN is

typically a few meters.