computer network - #01

7/31/2019 Computer Network - #01

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Computer Network

Computer Science, Brawijaya University

August 2007


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Course Outline

NetworkDefinition

NetworkClassification

NetworkComponent


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About The Past

InternetstartedbyARPANET

4Nodepresented4University,calledInternet

MessageProcessor(IMPs)using1822

Protocol(IENDocuments#1822)

Late,1972fundedbyUSMilitaryandrenamedDARPA

FinallycallInternet,runningunderIPProtocol

Suite,definedinRFC791(IP)andRFC

793(TCP)


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About The Past

BasicprinciplesofTCP/IPwerepublishedin

1974

AdoptionoftheDomainNameSystem(DNS)

in1983

EstablishmentoftheInternetEngineeringTaskForce(IETF)in1989

Formalre-namingoftheARPANETasthe

Internetin1990


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But What is a Network .. ?

Acombinationofhardware,software,and

media,whichtogetherallowmultiple

computingdevicestocommunicatewitheachother

Inshort,anetworkgivescomputerstheabilitytocommunicate.However,thatdefinition

couldapplytoalotofdifferenttypesof

networksAndthiscoursewilltalkaboutTCP/IPand

Ethernet


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But What is a Network .. ?


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Network Classification

ByLayer Accordingtosomebasic

referencesmodellikeOSIandInternet

ProtocolSuite

ByScale Accordingtothecoveragearea,

Local,Campus,Metropolitan,WideByConnectionMethod Ethernet,Wireless,

DialUp,PowerLineCommunication


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Network Classification

ByFunctionalRelationship ClientServer,

PeertoPeer,ActiveNetwork

ByTopology accordingtothenetwork

topology uponwhichthenetworkisbased:

Bus,Star,Ring,Mesh,TreeorHierarchical,etc

ByProtocol Computernetworksmaybe

classifiedaccordingtothecommunicationsprotocol thatisbeingusedonthenetworklike

ISDN,PDH,RS-232,SDH,SONET


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Network Components

NIC,NetworkInterfaceCard,istheexpansioncardinstallinacomputerto

connect,orinterfaceforacomputertonetwork.

HUB,ahubisthedevicethatconnectsallthe

segmentsofthatnetworktogether.SWITCH,Likeahub,aswitchconnects

multiplesegmentsofanetworktogether,with

oneimportantdifference.Whereasahubbroadcastsdata,switchforwardittocertainport


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Network Components

BRIDGE,anetworkdevicethatconnectstwo

similarnetworksegmentstogether.The

primaryfunctionofabridgeistokeeptrafficseparatedonbothsidesofthebridge

ROUTER,isanetworkdevicethatconnectsmultiple,oftendissimilar,networksegments

intoaninternetwork

GATEWAY,isanyhardwareandsoftwarecombinationthatconnectsdissimilarnetwork

environments.


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How to Eat T-Rex, ISO OSI Model

Aprotocolsuiteismosteasilydefinedasasetofrulesusedtodeterminehowcomputers

communicatewitheachother.Itissimilartolanguage

Themostcommonlyreferencedprotocol

model,OSImodel,wasdevelopedin1977bytheInternationalOrganizationforStandardizationtoprovidecommonground

whendescribinganynetworkprotocolTheOSImodelisusedtodescribewhattasks

aprotocolsuiteperformsasyouexplorehow

datamovesacrossanetwork


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OSI Model

TheOSIModel


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OSI Model

Youcanusemnemonicdevicestohelpyou

remembertheorderoftheOSImodellayers:

APSTNDP(fromtoptobottom).

Themostpopularmnemonicforthis

arrangementisAllPeopleSeemToNeedDataProcessing.

Areversemnemonic(fromPhysicalto

Application,bottomtotop)isPleaseDoNotThrowSausagePizzaAway.

Goodadvice,dontyouthink?


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OSI Model

PhysicalLayer

Generallyspeaking,Physicallayerconceptsdeal

withanetworkcomponentthatistangibleormeasurable

Additionally,thePhysicallayerspecifieshow

muchofthemediawillbeused(inotherwords,itssignalingmethod)duringdatatransmission

Ifanetworksignal usesallavailablesignal

frequencies(or,toputitdifferently,theentirebandwidth),thetechnologyissaidtouse

basebandsignaling


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OSI Model

DataLinkLayer

TheDataLinklayerisactuallymadeupoftwo

sublayers :MediumAccessControlandLogicalLinkControl

ProtocolsthatoperateattheDataLinklayerhave

severalresponsibilities,includingcreating,transmitting,andreceivingpackets.Additionally,

theDataLinklayerisresponsibleforphysical

(MAC)addressingandlogicallinkcontrol(LLC)processing,creatinglogicaltopologies,and

controllingmediaaccess


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OSI Model

NetworkLayer

TheNetworklayeroftheOSImodeldefines

protocolsthatensurethatthedataarriveatthecorrectdestination.Thisisprobablythemost

commonlydiscussedlayeroftheOSImodel.

ThemostimportantNetworklayerconceptsare:LogicalnetworkaddressingandRouting

IftheMACaddressistheDataLinklayer

physicaladdress,theprotocol-addressingschemeattheNetworklayerdefinesthelogical

address


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OSI Model

TransportLayer

TheTransportlayerdefinestheprotocolsfor

structuringmessagesandchecksthevalidityoftransmissions

KeyWord:Reliableend-to-enderrorandflow

control

TheprotocolsthatoperateattheTransportlayer

mainlyensurereliablecommunicationsbetween

upperpeerlayers


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OSI Model

SessionLayer

ProtocolsthatoperateattheSessionlayerofthe

OSImodelareresponsibleforestablishing,maintaining,andbreakingsessions,ordialogs

Thisisdifferentfromtheconnectionservices

providedattheTransportlayer

Sessionlayeroperatesatahigherleveland

looksatthebiggerpicturetheentire

conversation,notjustonesentence.ManygatewaysoperateattheSessionlayer


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OSI Model

PresentationLayer

ThePresentationlayerdoeswhatyoumightthink

itdoes:Itchangesthelook,orpresentation,ofthedatafromthelowerlayersintoaformatthat

theupper-layerprocessescanworkwith

Amongotherservices,thePresentationlayerdealswithencryption,datacompression,and

networkredirectors

Inaddition,thePresentationlayerdealswithcharacter-settranslation


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OSI Model

ApplicationLayer

NowIknowwhatyoumightbethinking:This

layerisformyprograms,right?Wrong

TheApplicationlayerdefinesseveralstandard

networkservicesthatfallintocategoriessuchas

filetransfer,printaccess,ande-mailrelay

Theapplicationsthataccessthesenetwork

servicesarelocatedabovetheApplicationlayer

(althoughsomepeoplesaythatapplicationsareanextensionoftheApplicationlayer)


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Networking Protocol The TCP/IP

TCP/IPisawidelypublishedopenstandardandiscompletelyindependentofany

hardwareorsoftwaremanufacturerTCP/IPcansenddatabetweendifferent

operatingsystems,fromsmallPCsallthe

waytomainframesandeverythinginbetween

TCP/IPisseparatedfromtheunderlying

hardwareandwillrunoverEthernet,TokenRing,orX.25networksand

evenoverdial-uptelephonelines


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Networking Protocol The TCP/IP

TCP/IPisaroutableprotocol,whichmeansit

cansenddatagrams overaspecificroute,

thusreducingtrafficonotherpartsofthenetwork

TCP/IPhasreliableandefficientdata-delivery

mechanisms

TCP/IPusesacommonaddressingscheme.

Therefore,anysystemcanaddressanyothersystem,eveninanetworkaslargeasthe

Internet


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TCP/IP Protocol

TheTransmissionControlProtocol/Internet

Protocol(TCP/IP)istheprotocolofchoice

todayLikeotherprotocols,isusedtoallowtwo

computerstocommunicateoveranetwork

However,TCP/IPisusednotonlyonlocal

areanetworks,butalsooverwidearea

networksandtheInternetActually,TCP/IPistheonlyprotocolinuseon

theInternet


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TCP/IP Protocol

AndWhatareTCP/IPDo?

Addressing.Eachhostisgiven(eithermanually

orautomatically)adotteddecimalIPaddressintheformatxxx.xxx.xxx.xxx wherexxxisanumberfrom0to255

Routing.OnTCP/IPnetworks,routingisafairlyinvolvedprocess.Inordertosendapacketthroughaninternetwork (liketheInternet),theroutermusthavethreepiecesofinformation:the

IPaddressofthesender,theIPaddressofthedestination,andtheIPaddressofthenextroutertowhichthepacketshouldbesent


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TCP/IP Protocol

AndWhatareTCP/IPDo?

Naming.TCP/IPhostsarenamedaccordingto

theDNSconvention.DNSisaservicethatresolvesnamestoIPaddressessothatwecan

usefriendlynameslikewww.trainsolutions.com

torefertocomputersinsteadofunfriendlyIPaddresseslike192.168.24.31

More..trytonameitbyyours


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TCP/IP Protocol

OSIModelandTCP/IP


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References

MartinP.Clark,DataNetworks,IPandThe

Internet.JohnWiley&Sons,2003

Wendell Odom,ComputerNetworking,First-Step.CiscoPress,April2004

DavidGroth,Network+StudyGuide,ThirdEdition.Sybex,2002