Transcript Transfer of data in ICT systems

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 is
transferred in a
network can be:
• metal wire
• fibre optic cable
• wireless.