components of computer networking

8/2/2019 Components of Computer Networking

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COMPONENTS OF COMPUTER

NETWORKING



Introduction

• Collection of hardware components and computersinterconnected by communication channels that allow sharing of resources and information.

• Sometimes considered a sub-discipline of electrical

engineering, telecommunications, computerscience, information technology or computerengineering, since it relies upon the theoretical andpractical application of these disciplines.

• Networks may be classified according to a wide varietyof characteristics such as the medium used to transportthe data, communications protocol used,scale, topology, and organizational scope.



Properties of computer networking

• Facilitate communications

• Permit sharing of files, data, and other types

of information

• Share network and computing resources

• May be insecure

•May interfere with other technologies

• May be difficult to set up



Conputer networking devices

• Computer networking devices are units that

mediate data in a computer network.

• Computer networking devices are also called

network equipment, Intermediate Systems (IS)

or InterWorking Unit (IWU).

• Units which are the last receiver or generate

data are called hosts or data terminal

equipment.



Different networking devices

Routers:

• Transfers data from one

network to another in

an intelligent way.

• Forwards data packets

to their destination by

the most efficient route.• WHOLE PROCESS:



Firewalls:

• A firewall is an importantaspect of a network withrespect to security.

• It typically rejects accessrequests from unsafe sourceswhile allowing actions fromrecognized ones.

• The vital role firewalls play innetwork security grows inparallel with the constantincrease in 'cyber' attacks for

the purpose of stealing/corrupting data,planting viruses, etc.



Repeaters:

• As all signals fade as they travelfrom one place to another, thenetwork cable is split up intosegments. Each segment is less

than the maximum length allowed.Joining the segments together is adevice known as a 'Repeater‘.

• A Repeater boosts the signal backto its correct level.

• Here are some typical maximumcable lengths:o Copper cable - 100 m

o Thick Ethernet -500m

o Thin Ethernet - 185m



Bridges:

• A Bridge does just what youwould expect it to do - it

joins two networks together

so as far as data packets areconcerned it looks like onelarge network

• A bridge is not as capable asa Router - but it is lessexpensive. Both networkshave to be using the sameprotocol (see protocol page).



Hub:

• There are many network topologies

available:

o Star - uses a hubo Tree - uses a hub

o Bus - does not use a hub

o Ring - does not use a hub

• To allow the Star and Tree network

topologies to work properly, each computer

must be able to send data packets to any

other computer on the network.

• The network 'Hub' allows computers to

share data packets within a network.

• Types:

o Passive Hub

o Active Hub

o Intelligent Hub



Switches:

• As a network cable can only haveone data packet in it at anyinstant, if two or more computerswant to place a data packet on to

the network at exactly the sametime, then a 'data collision' willtake place. This network protocolis set up to deal with this.

• Basically it declares the collideddata as unusable and forces the

two computers to re-send theirdata packets at a slightly differenttime.



Protocols:

• A 'NETWORK PROTOCOL' is the agreed method

of communication to be used within the

network.Each device / computer will use this

protocol.

• Some the things that need to be considered:-

o Speed of the network - for example 10Mbit /s

o Error checks of the data packets when they

arrive- how is it done

o Error correction of the data packets - method to

be useo Data packets received correctly - what

method/signal will be used to tell the other

machine that the data has arrived correctly

o How does the receiving machine know that the

sending machine has finished sending all of the

data? - what is the code to indicate this

o Data compression - does the protocol allow this

to take place and if so, what method does it use?

• Familiar names of protocols:

o TCP - the protocol that the internet uses

o Kermit - popular for use with modems

o X.25 - a packet switched protocol



Gateways:

• A gateway converts thedata passing between

dissimilar networks so thateach side cancommunicate with eachother. i.e converts datainto the correct network

protocol.• The gateway is a mixture of

hardware components andsoftware.

• This is unlike a standard'Bridge' which simply joinstwo networks together thatshare the same protocol.



Filters:

• If your network is to be kept secure it isoften essential that some filtering takesplace. For example, some staff wish to

work from home with their laptops andthey need to access files from withinthe company network.

• In this case a filter would be set up thataccepts data packets coming from thatparticular laptop.

• Other filtering rules would blockunwanted packets trying to come in.

• Just like Gateways , a Filter can be a mixof hardware and software components.

• Note that a filter can also prevent data

packets from leaving the companynetwork.

• A filter is an essential component of a'Firewall'.



Servers:

• Servers are used in smallnetworks, where everymachine is equally likely to

have a resource that anothermachine needs to use.

• One machine is linked to thescanner, whilst another is linkedto a printer. The game machine

is linked to the internet, whichall three machines can use. Thisis fine for small networks as thenumber of requests to use aresource is not going to be too

high.• Types: printer server, database

server, file server, email server,etc.



Workstation:

• A workstation is a high-endmicrocomputer designed fortechnical or scientific

applications.• They are commonly connected

to a local area network and runmulti-user operating systems.

• They are optimized for thevisualization and manipulation of different types of complex datasuch as 3D mechanical design,engineering simulation (e.g.computational fluid dynamics),

animation and rendering of images, and mathematical plots.



Cables:

• Cables transfers datafrom one point toanother on a

network. • There are three main

methods of transferring data:

o Electrical

o Radio or Microwave

o Infrared

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