Lesson 10_ History of computer networks and the Internet.pdf

The telephone network uses circuit switching to transmit information from sender to receiver – voice is transmitted at a constant speed between sender and receiver. In the early 1960s, because of the increasing importance of computers (while the cost of a computer was huge) and the advent of multitasking computers, people began to consider the problem of how to to connect computers together for sharing between users in different geographical areas.

1. Lesson10:Historyofcomputernetworksand
theInternet
Thisarticleispart12/16oftheseriesIntroductiontoComputer
Networks
Part1:SlideIntroductiontoComputerNetworks(English)
Part2:Lesson1:OverviewoftheInternetanditscomponents
Part3:Lesson2:Internetservices,APIs,andInternetprotocols
Part4:Lesson3:EdgeNetworkComponentsoftheInternet
Part5:[LatestVersion]BookComputerNetworking:ATop-Down
Approach8thEdition
Part12:Lesson10:HistoryofcomputernetworksandtheInternet
Part6:Lesson4:TransmissionMeansoftheInternet
Part7:Lesson5:CorenetworkcomponentsoftheInternet
Part8:Lesson6:Packetdelay,packetloss,andpacketswitching
networkthroughput.
Part9:Lesson7:ProtocollayeringandTCP/IPmodel
InpreviousarticlesoftheIntroductiontoComputerNetworksSeries,an
overviewofcomputernetworksandInternettechnologieswas
presented.Inthisarticle,wewilltakeabrieflookatthehistoryofthe
developmentoftheInternet

2. Historyofcomputernetworks
Today'scomputernetworksandInternetoriginatedintheearly
60s,whenthetelephonenetworkwasdominatingtheworld'scommunications
network.
Thedevelopmentofpacketswitchingnetworks1961-1972
Thetelephonenetworkusescircuitswitchingtotransmitinformationfrom
sendertoreceiver–voiceistransmittedataconstantspeedbetweensender
andreceiver.Intheearly1960s,becauseoftheincreasingimportanceof
computers(whilethecostofacomputerwashuge)andtheadventof
multitaskingcomputers,peoplebegantoconsidertheproblemofhowto
connectcomputersforsharingbetweenusersindifferentgeographicalareas.
Therearethreeindependentresearchgroupsintheworld,including:
ThefirstpublishedworkonpacketswitchingwasbyLeonardKleinrock(at
thattimeagraduatestudentatMIT).Usingqueuingtheory,Kleinrock'swork
demonstratedtheeffectivenessofpacketswitching.In1964,PaulBaranat
theRandInstitutebeganresearchingtheuseofpacketswitchesforvoice
securityonmilitarynetworks,andattheNationalPhysicalLaboratoryin
England,DonaldDaviesandRogerScantleburyalsoworkedondeveloping
theirideasonpacketswitching.

3. WorkatMIT,Rand,andNPLlaidthefoundationsfortoday'sInternet.But
today'sInternethasalonghistoryoftheresearchattitudeoftheearly1960s,
the"justbuilditandproveit"attitude.JCRLickliderandLawrenceRoberts–
twoofKleinrock'scolleaguesatMIT–continuetoleadthecomputerscience
programattheAdvancedResearchInstitute(ARPA)intheUnitedStates.
RobertsannouncedamasterplanforARPAnet,thefirstpacket-switched
computernetworkandthedirectancestoroftoday'spublic
Internet.
Thefirstpacketswitcheswerecalledinterfacemessageprocessors(IMPs),
andthecontracttobuildtheswitcheswasawardedtoBBN.OnLaborDay
1969,thefirstIMPwasinstalledatUCLAunderKleinrock'ssupervision,and
threeadditionalIMPswereinstalledshortlythereafterattheStanford
ResearchInstitute(SRI),UCSantaBarbara,andtheUniversityofCalifornia.
studyinUtah.
Thesefourlargenetworknodesinstalledinlate1969weretheearly
precursorsoftheInternet.Kleinrockrecallsthenetwork'sfirstuse,toperform
aremoteloginfromUCLAtoSRI,crashedthesystem.
By1972,ARPAnethadgrowntoabout15nodesandwasfirstdemonstrated
byRobertKahnatthe1972InternationalConferenceonComputer
Communications.Thefirst“host-to-host”protocolbetweenTheARPAnet
system,calledtheNetworkControlProtocol(NCP),wascompleted(RFC
001).RayTomlinsonwrotethefirstemailprogramin1972.
MonopolyandInternetwork1972–1980
ALOHAnet,anetworkofaffiliateduniversitiesontheHawaiianislands,oras
DARPA'ssatellitetelevisionpackage(RFC829)andpackageradionetworks.

4. Telenetisacommercialpacket-switchednetworkproductbased
onBBN'sARPAnettechnology.
TheCyclades,aFrenchpacketcircuitnetworkpioneeredbyLouisPouzin.
Time-sharingnetworkssuchasTymnetandtheGEInformationServices
network,amongothers,duringthelate1960sandearly1970s.
IBMSNA(1969-1974),operatedinparallelwithARPAnet.

5. Severalothernetworksareunderdevelopment.Developingastructureto
connectnetworksisgrowingrapidly.Pioneeringworkoninterconnection
networks(undertheauspicesoftheDefenseAdvancedProjectsAgency
(DARPA)),inessencecreatinganetworkofnetworks,wascarriedoutby

6. VintonCerfandRobertKahn;Theterminternettingwascoinedto
describethisjob.
ThearchitecturalprinciplesareexpressedintheTCPprotocol.However,early
versionsofTCPwerequitedifferentfromtoday'sTCP.EarlyversionsofTCP
usedaresendservicecombinedwithapacketforwardingservice(which
todayishandledbytheIPprotocol)toensurereliability.
InitialexperimentationwithTCP,combinedwiththerealizationofthe
importanceofanunreliable,uncontrolledtransportservice,forapplications
suchasInternettelephony,ledtotheseparationofIPfromtheprotocolTCP
andthedevelopmentoftheUDPprotocol.ThethreeimportantInternet
protocolsweseetoday,TCP,UDP,andIP,wereconceptsformedinthelate
1970s.
InadditiontoDARPAresearchrelatedtotheInternet,manyotherimportant
cyberactivitieshavebeenconducted.InHawaii,NormanAbramson
developedALOHAnet,apacket-basedradionetworkthatallowedmultiple
remoteaccess.TheALOHAprotocolwasthefirstmultiple-accessprotocol,
allowingusersindifferentgeographicalareastoshareasinglebroadcast
medium(e.g.,aradiofrequency).
MetcalfeandBoggsbuiltonAbramson'smultipleaccessprotocolworkwhen
theydevelopedtheEthernetprotocol,basedonthebroadcastprinciple.
Interestingly,MetcalfeandBoggs'sEthernetprotocolwasmotivatedbythe
needtoconnectmultiplecomputers,printers,andshareddrives.Manyyears
ago,beforethecomputerrevolutionandtheexplosionofnetworks,Metcalfe
andBoggslaidthefoundationfortoday'sLANcomputers.
Ethernettechnologyrepresentsanimportantstepforwardforinternetworking.
EachlocalEthernetnetworkisanetwork,andasthenumberofLANs
increasesrapidly,theneedtoconnectLANsbecomesincreasinglyimportant
Networkdevelopment1980-1990

7. Inthelate1970s,therewereabout200serversconnectedtoARPAnet.By
thelate1980s,thenumberofserversconnectedtoapublicnetworksimilarto
today'sInternetnumberedhundredsofthousands.Thisistheyearofstrong
developmentofthenetwork.Thisgrowthcomesfromeffortstocreate
computernetworksthatconnectuniversities.
BITNETprovidesemailandfiletransferbetweenuniversitiesinNorth
America.CSNETwasestablishedtoconnectresearcherswhodidnothave
accesstotheARPAnetnetwork.In1986,NSFNETwascreatedtoprovide
connectivitytoNSF-fundedsupercomputingcenters.NSFNET'smainline
initiallyhadaspeedof56kbps,thenincreasedto1.5Mbpsbytheendofthe
decade,anditwasusedasthemainlinetoconnectareas.
ManycomponentsofthemodernInternetarchitectureemergedwithinthe
ARPAnetcommunity.TCP/IPofficiallybecameaprotocolstandardfor
ARPAnet,replacingtheNCPprotocolonJuly1,1983.Inthelate1980s,TCP
wasgivenanti-congestioncontrolcapabilities.DNS(mappingbetween
computernamesontheInternetand32-bitIPaddresses)wasalso
developed.
AlongwiththedevelopmentofARPAnet(mainlyAmericanefforts),theFrench
alsodevelopedtheMinitelprojectintheearly1980s,withtheambitionto
bringpacket-switchingnetworkstoeveryhome.TheMinitelsystem,funded
bythegovernment,consistsofpublicpacket-switchednetworks(basedonthe
X.25protocolpacket),Minitelservers,andinexpensiveterminalswith
low-speedmodems.pre-mounted.Minitelachievedgreatsuccessin1984
whentheFrenchgovernmentdistributedfreeMinitelterminalstohouseholds
inneed.
Minitelsitesincludefreesitessuchasphonenumbersaswellasseparate
paidsites.Atitspeakinthemid-1990s,itofferedmorethan20,000services,
fromhomebankingtospecializedresearchdatabases.Itisusedby20
percentoftheFrenchpopulationandgeneratesmorethanabilliondollarsin
revenueeachyearwhilecreating10,000jobs.Minitelbecamealargepartof
Frenchhouseholds10yearsbeforemostAmericanshadheardofthe
Internet.
TheexplosionoftheInternetinthe1990s
The1990smarkedaseriesofeventsforthecontinueddevelopmentand
near-futurecommercializationoftheInternet.TheancestoroftheInternet,
ARPAnet,graduallydisappeared.MILNETandtheDefensePacket
Networkevolvedinthe1980stohandlemostofthetrafficrelatedtotheUS

8. DepartmentofDefense,andNSFNETwasusedastheprimary
networkconnectingregionalnetworkswithintheUSandnationalnetworks.
otheroutside.
In1991,NSFNETliftedrestrictionsoncommercialuseofNSFNET.NSFNET
wouldalsobephasedoutin1995,withthemainnetworktrafficcarriedby
commercialInternetServiceProviders.
Themaineventof1990wastheemergenceoftheWorldWideWeb,bringing
theInternetintohomesandbusinessesaroundtheworld.TheWebservesas
aplatformthatenablesthedeploymentofhundredsofnewapplications.
TheWebwasinventedatCERNbyTimBemers-Leebetween1989and
1991,basedonideasderivedfromearlierworkonhypertextfromthe1940s
byVannevarBushandfromthe1960sbyTedNelson.Bemers-Leeandhis
colleaguesdevelopedthefirstversionsofHTML,HTTP,webserver,and
browser–thefourmaincomponentsofwebapplications.
Bytheendof1993,therewereabouttwohundredwebserversinoperation.
Aroundthistimeseveralresearchersdevelopedgraphicalwebbrowsers,
includingMarcAndreessen,wholedthedevelopmentoftheMosaicgraphical
browser.In1994MarcAndreessenandJimClarkfoundedMosaic
Communications,whichlaterbecameNetscapeCommunications
Corporation.In1995,collegestudentswereusingMosaicandNetscapeto
surftheWebeveryday.
Aroundthistime,companies,largeandsmall,beganoperatingWebservers
andtransactinge-commerceontheweb.In1996,Microsoftbeganmaking
browsers,startingthebrowserwarbetweenNetscapeandMicrosoft,which
Microsoftwonafewyearslater.
Thesecondhalfofthe1990swasaperiodofintensegrowthandinnovation
fortheInternet,withlargecorporationsandthousandsofstartupscreating
Internetproductsandservices.Internetemailcontinuestogrowwithrich
featuresforemailreaders,offeringaddressbooks,fileattachments,and
multimediacommunications.Bytheendofthemillennium,theInternet
supportedhundredsofpopularapplications,includingfourwell-known
applicationgroups:
E-mail,includingattachmentsandemailsaccessiblefromtheWeb.
TheWeb,includingwebbrowsingandthecommercialInternet.
Instantmessagingwithcontactlists,pioneeredbyICQ.
Peer-to-peersharingofMP3files,pioneeredbyNapster.

9. What'sinterestingisthatthefirsttwogroupsofpopularappscamefrom
researchcommunities,whilethelasttwogroupswerecreatedbyafewyoung
entrepreneurs.
Theperiod1995-2001wasaperiodof"upsanddowns"fortheInternetin
financialmarkets.Beforetheywereprofitable,hundredsofInternetstartups
offeredtheirservicesforfreeandatthesametimelistedtheircompanieson
thestockmarket.Manycompanieshavebeenworthbillionsofdollarswithout
anysignificantprofits.Internetstockscrashedin2000-2001,andmany
startupshadtoclosetheirdoors.
However,severalcompanieshaveemergedasbigwinnersintheInternet
space,includingMicrosoft,Cisco,Yahoo,eBay,Google,andAmazon.
ThedevelopmentoftheInternetinrecentyears
Innovationincomputernetworkingcontinuesatarapidpace.Progressis
beingmadeonallfronts,includingthedeploymentofnewapplications,
contentdistribution,Internettelephony,highertransmissionspeedsinLANs,
andfasterrouters.Butthreedevelopmentsworthnotinginparticulararethe
riseofhigh-speednetworkaccess(includingwirelessaccess),security,and
P2Pnetworks.
ThegrowthofbroadbandInternetaccess,throughcableandDSL,prepared
foraproliferationofnewmultimediaapplications,includingvoiceandvideo
overIP,videosharing,andtelevisionoverIP.Theubiquityandgrowing
availabilityofhigh-speed(11Mbpsandhigher)andmedium-speed(hundreds
ofkbps)WiFinetworksmakeitpossibletoaccesstheInternetviamobile
phonenetworksnotonlynotonlymaintainseamlessconnectivitybutalsoto
facilitateasetofexcitingnewservices.
Afteraseriesofprominentdenial-of-serviceattacksonwebserversinthelate
1990s,andanincreaseinattacksbyworms(e.g.,Blasterworms),network
securitybecameamajortopic.veryimportant.Theseattackshaveledtothe
developmentofintrusiondetectionsystemsthatprovideearlywarningofan

10. attack,andtheuseoffirewallstofilteroutunwantedtrafficbeforeit
enters.Network.
ThelastinnovationthatwepayspecialattentiontoisP2Pnetworks.Normally,
theuser'scomputercanconnectcontinuously,soitcanshareinformation
continuously.TherehavebeenmanyP2Psuccessstoriesoverthepast
decade,includingP2Pfilesharing(Napster,Kazaa,Gnutella,eDonkey,
LimeWire,…),filedistribution(BitTorrent),VoiceoverIP(Skype),andIPTV
(PPLive,PPStream).
summary
Thus,thisarticleendswiththehistoryofthedevelopmentofcomputer
networksandtheInternet.Inthenextlesson,wewillsolveexercises
surroundingthepreviouslessons.
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