Networks. What is a computer network? A network is two or more computers that are linked together so that they are able to share resources.

Networks

Networks

What is a computer network?

A network is two or more computers that are linked together so that they are able to share resources.

Networks

Shared resources include

• Hardware – printers, scanners, storage, etc.

• Software – need only be installed on one computer.

• Data (e.g. database files).• An Internet connection.

Networks

LANs and WANs

Local area networks:• Confined to a small area. • Usually located in a single

building. • Use cable, wireless,

infrared and microwave links that are usually owned by the organization.

• Cheap to build.• Cheap to run.

Wide area networks:• Cover a wide geographical

area (i.e., between cities, countries and even continents).

• In lots of different buildings and cities, countries, etc.

• Use more expensive telecommunication links that are supplied by telecom companies.

• Expensive to build.• Expensive to run.

Networks

An ICT network consists of

• Hardware/communication devices• Network software• Data transfer media

Networks

Communication devices

A network interface card:

• prepares data for sending over the network

• sends the data• controls the flow of

data.

Networks

Communication devices

A hub:• is used to join

computers in a network

• allows the connection of cables

• allows the sharing of files and Internet access

Networks

Communication devices

A switch:• is similar to a hub but more intelligent• can look at a packet of data to decide

where it should go• reduces the number of packets of data

on a network, which speeds it up

Networks

Communication devices

A router:• can be wired or

wireless• is used to join

several networks together

• is often used to connect several computers in the home to the Internet

Networks

Network software

Network software consists of:• Network operating systems – specialist

operating systems designed specifically for networks.

• Network management software – used to help a network manager run a network by keeping track of software, keeping software up-to-date, installing software security patches, helping to manage the help-desk, etc.

Networks

Data transfer media

The medium/method by which the data istransferred in anetwork can be:

• metal wire• fibre optic cable• wireless.