Networks
Computer networks
A computer network is a set of computers
connected to each other so they can share resources and exchange information.
We can
divide computer networks into three categories, depending on their size:
II.
Metropolitan area networks, made up of several LANs
III.
Wide area networks, covering a country or continent.
LANs can
also be categorised according to the way in which the different machines are
are connected to each other.
Peer-to peer networks
and client-server networks
Networks can be
organised in accordance with two types of functional approach.
Client-server
networks. A server is a computer responsable for centralising or managing a
given function required in a network. It can share information, apply access
rules to the information, define the users who can access the network and
control access to resources and devices, among other things. The other
computers in the network are known as clients
or terminals and are stations from
which users communicate with the central computer.
Point to point
networks. These are also known as peer-to-peer
networks. In these types of networks, all the nodes or work stations act
simultaneously as clients and servers.
Topologies
The topology is the way we can connect different work
stations and transmission hardware (cables and other network devices) in a
local area network. There are a variety of
Elements in a network
All computer
networks have a logical component,
which is an operating system and applications that work on a network, and a physical component connecting the
different computers to each other.
Each computer
needs an adaptor or network card to send information to the other computers and receive
information back.
The hub distributes all of the information
it receives between the other computers in the network.
It can be
replaced by a switch, which sends
the data it receives onñy the recipient.
This information
travels down a transmission medium, normally a cable similar to a telephone
wire with an RJ45 connector the end.
Coaxial and fibre optic cables are also used.
https://www.youtube.com/watch?v=ZvWn5xBflUs
https://www.youtube.com/watch?v=ZvWn5xBflUs
Twisted-pair cable
networks
The UTP (unshielded
twisted pair) cable consists of
copper or aluminium wires interlaced in pairs to avoid interference. Depending on
the number of wires used and the length of each strand, different transmission
speeds are obtained, which the industry calls the category (CAT). It can transmit at a speed of 1
Gbps and the distance of propagation is usually 150 m. The conector used is the
RJ45.
The STP (shielded
twisted pair) cable is a variant of the UTP which is even more secure in
transmission. It increases the amount of insulation around the group of cables
and the immunity to noise it is more expensive.
Activities
We have looked at the advantages of using computer
networks.
Can you think of any disadvantages? Write them in your
exercise book.
Wireless networks
Wireless networks, known as WLANs (Wireless LAN’s),
use electromagnetic waves to transmit data. All computers need to have a
wireless network card.
Networks with a combination of wired and wireless
devices use wireless access points (WAP) that we can use to transmit data
through wires or electromagnetic waves.
Shared Internet access
Computers in a network can share a single Internet
connection. Computer networks can connect to the Internet in two ways:
Internet
Connection Sharing (ICS), where all communication is through one
computer that must be switched on all time.
Using a router,
which detects data and directs it to and from the internet.
One disadvantage of network sharing is that the
computer with all the elements must be switched on at all times so that the
other users access those elements.
To overcome this problem, we can use network storage systems and print servers.
Activities
I.
In your exercise book, draw a diagram of a local area
network made up of two computers with wired connections and two with wireless connections.
II.
Use the Internet to find out what Bluetooth technology
is.
Glossary
Connector:
coaxial:
fibre optic
electromagnetic wave:
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