Unit 1 Information Technology for student👩‍🎓.pdf

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1. Unit 1 : Information Technology
Dr.DurgawatiKushwaha
Assistant Professor

2. Network Topology
•Network topologyis the arrangement of the elements (links,nodes, etc.) of a communication network.
•Network topology can be used to define or describe the arrangement of various types of
telecommunication networks, includingcommand and controlradio networks,industrialfield
bussesandcomputer networks.
•Network topology is thetopologicalstructure of a network and may be depicted physically or logically.
•It is an application ofgraph theory wherein communicating devices are modeled as nodes and the
connections between the devices are modeled as links or lines between the nodes.
•Physical topology is the placement of the various components of a network (e.g., device location and
cable installation), while logical topology illustrates how data flows within a network.
•Examples of network topologies are found in local area networks (LAN), a common computer network
installation.

3. Topologies
•Physicaltopology:
Thetransmissionmediumlayoutusedtolinkdevicesisthephysicaltopologyofthe
network.Forconductiveorfiberopticalmediums,thisreferstothelayoutofcabling,
thelocationsofnodes,andthelinksbetweenthenodesandthecabling.
Thephysicaltopologyofanetworkisdeterminedbythecapabilitiesofthenetwork
accessdevicesandmedia,thelevelofcontrolorfaulttolerancedesired,andthecost
associatedwithcablingortelecommunicationcircuits.
•Logicaltopology:
•Logicaltopologyisthewaythatthesignalsactonthenetworkmedia,orthewaythat
thedatapassesthroughthenetworkfromonedevicetothenextwithoutregardto
thephysicalinterconnectionofthedevices.
•Anetwork'slogicaltopologyisnotnecessarilythesameasitsphysicaltopology.

4. Types of Network Topology

5. Contd….
Bus topology
•The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone
cable.
•Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable.
•When a node wants to send a message over the network, it puts a message over the network. All the stations available in
the network will receive the message whether it has been addressed or not.
•The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks.
•The configuration of a bus topology is quite simpler as compared to other topologies.
•The backbone cable is considered as a "single lane" through which the message is broadcast to all the stations.
•The most common access method of the bus topologies is CSMA (Carrier Sense Multiple Access).
CSMA:Itisamediaaccesscontrolusedtocontrolthedataflowsothatdataintegrityismaintained,
i.e.,thepacketsdonotgetlost.Therearetwoalternativewaysofhandlingtheproblemsthatoccurwhen
twonodessendthemessagessimultaneously.
•CSMACD:CSMACD(Collisiondetection)isanaccessmethodusedtodetectthecollision.Once
thecollisionisdetected,thesenderwillstoptransmittingthedata.Therefore,itworkson"recovery
afterthecollision".
•CSMACA:CSMACA(CollisionAvoidance)isanaccessmethodusedtoavoidthecollisionby
checkingwhetherthetransmissionmediaisbusyornot.Ifbusy,thenthesenderwaitsuntilthemedia
becomesidle.Thistechniqueeffectivelyreducesthepossibilityofthecollision.Itdoesnotworkon
"recoveryafterthecollision".

6. Contd….
Advantages
•Low-cost cable
•Moderate data speeds
•Familiar technology
•Limited failure
Disadvantages
•Extensive cabling
•Difficult troubleshooting
•Signal interference
•Reconfiguration difficult
•Attenuation(lossofsignalleadsto
communicationissues.Repeatersareusedto
regeneratethesignal.)

7. •Ring Topology:
Ring topology is like a bus topology, but with connected ends.
The node that receives the message from the previous computer will retransmit to the next node.
The data flows in one direction, i.e., it is unidirectional.
The data flows in a single loop continuously known as an endless loop.
It has no terminated ends, i.e., each node is connected to other node and having no termination point.
The data in a ring topology flow in a clockwise direction.
The most common access method of the ring topology istoken passing.
•Token passing:It is a network access method in which token is passed from one node to another node.
•Token:It is a frame that circulates around the network.
Working of Token passing
•A token moves around the network, and it is passed from computer to computer until it reaches the
destination.
•The sender modifies the token by putting the address along with the data.
•The data is passed from one device to another device until the destination address matches.
•Once the token received by the destination device, then it sends the acknowledgment to the sender.
•In a ring topology, a token is used as a carrier.
Contd….

8. Contd….
Advantages
•Network Management
•Product availability
•Cost
•Reliable
Disadvantages
•Difficult troubleshooting
•Failure
•Reconfiguration difficult
•Delay

9. •Star Topology
Contd….
•Startopologyisanarrangementofthenetworkinwhicheverynodeis
connectedtothecentralhub,switchoracentralcomputer.
•Thecentralcomputerisknownasaserver,andtheperipheraldevices
attachedtotheserverareknownasclients.
•CoaxialcableorRJ-45cablesareusedtoconnectthecomputers.
•HubsorSwitchesaremainlyusedasconnectiondevicesinaphysical
startopology.
•Startopologyisthemostpopulartopologyinnetworkimplementation.

10. Contd….
Advantages
•Efficient troubleshooting
•Network control
•Limited failure
•Familiar technology
•Easily expandable
•Cost effective
•High data speeds
Disadvantages
•A Central point of failure
•Cable

11. •Tree topology:
Combines the characteristics of bus topology and star topology.
A tree topology is a type of structure in which all the computers are connected with each other in
hierarchical fashion.
The top-most node in tree topology is known as a root node, and all other nodes are the
descendants of the root node.
There is only one path exists between two nodes for the data transmission. Thus, it forms a
parent-child hierarchy.
Contd….
Advantages Disadvantages
Support for broadbandtransmissionDifficult troubleshooting
Easily expandable & manageableHigh cost
Error detection Failure
Limited failure Reconfiguration difficult
Point-to-point wiring

12. •Mesh topology
Mesh technology is an arrangement of the network in which computers are
interconnected with each other through various redundant connections.
There are multiple paths from one computer to another computer.
It does not contain the switch, hub or any central computer which acts as a central point
of communication.
The Internet is an example of the mesh topology.
Mesh topology is mainly used for WAN implementations where communication failures
are a critical concern.
Mesh topology is mainly used for wireless networks.
Mesh topology can be formed by using the formula:
Number of cables = (n*(n-1))/2;
Where n is the number of nodes that represents the network.
Contd….

13. •Mesh topology is divided into two categories:
Fully connected mesh topology
Partially connected mesh topology
Contd….
•FullMeshTopology:Inafullmeshtopology,eachcomputerisconnectedtoallthecomputersavailableinthenetwork.
•PartialMeshTopology:Inapartialmeshtopology,notallbutcertaincomputersareconnectedtothosecomputerswithwhich
theycommunicatefrequently.
Advantages Disadvantages
Reliable Cost
Fast Communication Managementis difficult
Easier Reconfiguration Efficiency(redundant connections are high that reduces
the efficiency of the network)

14. •Hybrid Topology
Contd….
•ThecombinationofvariousdifferenttopologiesisknownasHybrid
topology.
•AHybridtopologyisaconnectionbetweendifferentlinksandnodesto
transferthedata.
•Whentwoormoredifferenttopologiesarecombinedtogetheristermedas
Hybridtopologyandifsimilartopologiesareconnectedwitheachotherwill
notresultinHybridtopology.
•Forexample,ifthereexistaringtopologyinonebranchofICICIbankand
bustopologyinanotherbranchofICICIbank,connectingthesetwo
topologieswillresultinHybridtopology.
Advantages Disadvantages
Reliable Complex design
Scalable Costly Hub
Flexible Costly infrastructure
Effective

15. Transmission modes
•Thewayinwhichdataistransmittedfromonedevicetoanotherdeviceisknownastransmissionmode.
•Thetransmissionmodeisalsoknownasthecommunicationmode.
•Eachcommunicationchannelhasadirectionassociatedwithit,andtransmissionmediaprovidethe
direction.Therefore,thetransmissionmodeisalsoknownasadirectionalmode.
•Thetransmissionmodeisdefinedinthephysicallayer.
•TheTransmissionmodeisdividedintothreecategories:
Simplex mode
Half-duplex mode
Full-duplex mode

16. •Simplex mode
Contd….
•InSimplexmode,thecommunicationisunidirectional,i.e.,thedataflowinonedirection.
•Adevicecanonlysendthedatabutcannotreceiveitoritcanreceivethedatabutcannotsendthedata.
•Thistransmissionmodeisnotverypopularasmainlycommunicationsrequirethetwo-wayexchangeofdata.Thesimplex
modeisusedinthebusinessfieldasinsalesthatdonotrequireanycorrespondingreply.
•Theradiostationisasimplexchannelasittransmitsthesignaltothelistenersbutneverallowsthemtotransmitback.
•KeyboardandMonitoraretheexamplesofthesimplexmodeasakeyboardcanonlyacceptthedatafromtheuserand
monitorcanonlybeusedtodisplaythedataonthescreen.
•Themainadvantageofthesimplexmodeisthatthefullcapacityofthecommunicationchannelcanbeutilizedduring
transmission.
AdvantageofSimplexmode:
•Insimplexmode,thestationcanutilizetheentirebandwidthofthecommunicationchannel,sothatmoredatacanbe
transmittedatatime.
DisadvantageofSimplexmode:
•Communicationisunidirectional,soithasnointer-communicationbetweendevices.

17. •Half-Duplex mode
Contd….
•InaHalf-duplexchannel,directioncanbereversed,i.e.,thestationcantransmitandreceivethedataaswell.
•Messagesflowinboththedirections,butnotatthesametime.
•Theentirebandwidthofthecommunicationchannelisutilizedinonedirectionatatime.
•Inhalf-duplexmode,itispossibletoperformtheerrordetection,andifanyerroroccurs,thenthereceiverrequeststhe
sendertoretransmitthedata.
•AWalkie-talkieisanexampleoftheHalf-duplexmode.InWalkie-talkie,onepartyspeaks,andanotherpartylistens.After
apause,theotherspeaksandfirstpartylistens.Speakingsimultaneouslywillcreatethedistortedsoundwhichcannotbe
understood.
AdvantageofHalf-duplexmode:
•Inhalf-duplexmode,boththedevicescansendandreceivethedataandalsocanutilizetheentirebandwidthofthe
communicationchannelduringthetransmissionofdata.
DisadvantageofHalf-Duplexmode:
•Inhalf-duplexmode,whenonedeviceissendingthedata,thenanotherhastowait,thiscausesthedelayinsendingthedata
attherighttime.

18. •Full-duplex mode
Contd….
•InFullduplexmode,thecommunicationisbi-directional,i.e.,thedataflowinboththedirections.
•Boththestationscansendandreceivethemessagesimultaneously.
•Full-duplexmodehastwosimplexchannels.Onechannelhastrafficmovinginonedirection,andanotherchannelhas
trafficflowingintheoppositedirection.
•TheFull-duplexmodeisthefastestmodeofcommunicationbetweendevices.
•Themostcommonexampleofthefull-duplexmodeisatelephonenetwork.Whentwopeoplearecommunicatingwitheach
otherbyatelephoneline,bothcantalkandlistenatthesametime.
AdvantageofFull-duplexmode:
•Boththestationscansendandreceivethedataatthesametime.
DisadvantageofFull-duplexmode:
•Ifthereisnodedicatedpathexistsbetweenthedevices,thenthecapacityofthecommunicationchannelisdividedintotwo
parts.

19. Differences b/w Simplex, Half-duplex and Full-duplex mode
Basis for
comparison
Simplex mode Half-duplex mode Full-duplex mode
Direction of
communication
Insimplexmode,the
communicationisunidirectional.
Inhalf-duplexmode,thecommunicationis
bidirectional,butoneatatime.
Infull-duplexmode,the
communicationisbidirectional.
Send/Receive Adevicecanonlysendthedata
butcannotreceiveitoritcan
onlyreceivethedatabutcannot
sendit.
Boththedevicescansendandreceivethe
data,butoneatatime.
Boththedevicescansendand
receivethedatasimultaneously.
Performance Theperformanceofhalf-duplex
modeisbetterthanthesimplex
mode.
Theperformanceoffull-duplexmodeisbetter
thanthehalf-duplexmode.
TheFull-duplexmodehasbetter
performanceamongsimplexand
half-duplexmodeasitdoubles
theutilizationofthecapacityof
thecommunicationchannel.
Example ExamplesofSimplexmodeare
radio,keyboard,andmonitor.
Exampleofhalf-duplexisWalkie-Talkies. ExampleoftheFull-duplexmode
isatelephonenetwork.

20. Netiquette
•Netiquetteis a made-up word from the wordsnetandetiquette.
•Netiquette thus describes therules of conductforrespectful and appropriate
communication on the internet.
•Netiquette is often referred to asetiquette for the internet.
•These are not legally binding rules, butrecommended rules of etiquette.
•Netiquette is mostly used for dealing with unknown people on the internet.
•Therules of netiquettevery depending on theplatformand itsparticipants.
•Generally, it is up to the operator of a website or communication app to specify the type and
scope of netiquette.
•It is also their responsibility to monitor compliance with thesebasic rulesandto penalize
violations of them.

21. Netiquette: General rules of conduct
•Stick to the rules of conduct online that you follow in real life
•Netiquette: Think of the person
•Present your best side online
•Read first, then ask
•Pay attention to grammar and punctuation
•Respect the privacy of others
•Respect the time and bandwidth of others
•Forgive the mistakes of others
•Don't abuse your power
•Helpkeep flame warsunder control
•Know where you are in cyberspace
•Hate speech and netiquette