Peer-to-peer network

Networkcharacteristics

Peer-to-peernetworkisanetworkstructureidea.Anessentialdifferencebetweenitandthecurrentdominantclient/server(Client/Server)structure(thatis,thestructureadoptedbytheWWW)inthecurrentnetworkisthatthereisnocentralnode(orcentralserver)intheentirenetworkstructure.IntheP2Pstructure,eachnode(peer)mostlyhasthreefunctionsatthesametime:informationconsumer,informationprovider,andinformationcommunication.Intermsofcomputingmode,P2PbreaksthetraditionalClient/Server(C/S)mode,andthestatusofeachnodeinthenetworkisequal.Eachnodenotonlyactsasaserver,providesservicesforothernodes,butalsoenjoystheservicesprovidedbyothernodes.

Simplyput,P2Pistoconnectpeopledirectly,allowingpeopletointeractdirectlythroughtheInternet.P2Pmakescommunicationonthenetworkeasier,moredirectsharingandinteraction,andtrulyeliminatesmiddlemen.

AnotherimportantfeatureofP2PistochangethecurrentEthernetstation-centricstateoftheInternet,returnto"decentralization",andreturnpowertousers.

Thepeer-to-peernetworkisasuccessfulexpansionofthedistributedconcept.Itdistributestheburdenoftheserverinthetraditionalwaytoeachnodeinthenetwork,andeachnodewillundertakelimitedstorageandcomputingtasks.Themorenodesthatareaddedtothenetwork,themoreresourcesthenodescontribute,andthehigherthequalityoftheirservices.

Peer-to-peernetworkscanuserelativelypowerfulcomputers(personalcomputers)thatexistattheedgeoftheInternettoperformmoreadvancedtasksthanclient-basedcomputingtasks.ModernPCshaveextremelyfastprocessors,massiveamountsofmemory,andlargeharddrives,andtheycannotfullyexploitthepotentialofthesedeviceswhenperformingroutinecomputingtasks(suchasbrowsinge-mailandtheWeb).ModernPCscaneasilyactasclientsandservers(peers)formanytypesofapplicationsatthesametime.

ThecharacteristicsofP2Pnetworktechnologyarereflectedinthefollowingaspects:

Decentralization

Theresourcesandservicesinthenetworkarescatteredonallnodes,andtheinformationisTherealizationoftransmissionandservicesarecarriedoutdirectlybetweennodes,withouttheinterventionofintermediatelinksandservers,andpossiblebottlenecksareavoided.ThedecentralizedbasiccharacteristicsofP2Pbringitsadvantagesinscalabilityandrobustness.

Scalability

InaP2Pnetwork,asusersjoin,notonlydoesthedemandforservicesincrease,buttheoverallsystemresourcesandservicecapabilitiesarealsoexpandingsimultaneously,alwaysItiseasiertomeettheneedsofusers.Intheory,itsscalabilitycanbeconsideredalmostunlimited.Forexample:InthetraditionalwayofdownloadingfilesviaFTP,whendownloadingusersincrease,thedownloadspeedwillbecomeslowerandslower.However,theP2Pnetworkisjusttheopposite.Themoreusersjoin,themoreresourcesareprovidedintheP2Pnetwork.,Thedownloadspeedisfaster.

Robustness

P2Parchitectureisinherentlyresistanttoattacksandhighlyfault-tolerant.Sincetheserviceisdistributedamongvariousnodes,thedestructionofsomenodesorthenetworkwillhavelittleimpactonotherparts.P2Pnetworksgenerallycanautomaticallyadjusttheoveralltopologywhensomenodesfailtomaintaintheconnectivityofothernodes.P2Pnetworksareusuallyestablishedinaself-organizingmannerandallownodestojoinandleavefreely.

Highcostperformance

PerformanceadvantageisanimportantreasonwhyP2Piswidelyconcerned.Withthedevelopmentofhardwaretechnology,thecomputingandstoragecapacityofpersonalcomputers,aswellastheperformanceofnetworkbandwidth,haveincreasedrapidlyinaccordancewithMoore'stheorem.AdoptingtheP2ParchitecturecaneffectivelyutilizealargenumberofordinarynodesscatteredontheInternet,anddistributecomputingtasksorstoreddatatoallnodes.Utilizetheidlecomputingpowerorstoragespacetoachievethepurposeofhigh-performancecomputingandmassstorage.Atpresent,theapplicationofP2Pinthisareaismostlyinacademicresearch.Oncethetechnologyismatureandcanbepromotedintheindustrialfield,itcansavemanycompaniesthecostofpurchasinglarge-scaleservers.

Privacyprotection

InaP2Pnetwork,becausethetransmissionofinformationisdispersedamongnodeswithoutgoingthroughacentralizedlink,theuser’sprivateinformationmaybeeavesdroppedandleakedSexisgreatlyreduced.Inaddition,thecurrentmethodofsolvingInternetprivacyproblemsmainlyadoptsrelayandforwardingtechnology,thushidingcommunicationparticipantsinnumerousnetworkentities.Insometraditionalanonymouscommunicationsystems,therealizationofthismechanismreliesoncertainrelayservernodes.InP2P,allparticipantscanprovidethefunctionofrelaying,whichgreatlyimprovestheflexibilityandreliabilityofanonymouscommunication,andcanprovideuserswithbetterprivacyprotection.

Loadbalancing

IntheP2Pnetworkenvironment,sinceeachnodeisbothaserverandaclient,itreducestherequirementsforthecomputingandstoragecapabilitiesofthetraditionalC/Sstructureserver.Theresourcesaredistributedacrossmultiplenodes,whichbetterrealizestheloadbalanceoftheentirenetwork.

Becausethepeer-to-peernetworkdoesnotrequireadedicatedserverfornetworksupport,andothercomponentsarenotneededtoimprovetheperformanceofthenetwork,thenetworkingcostislow,anditissuitableforscenarioswithfewpersonnelandsimplenetworking.,Soitisoftenusedinsmallandmedium-sizedenterprisesorhomeswithsmallnetworks.

Advantagesanddisadvantages

Advantages

Comparedwithclient/servernetworks,peer-to-peernetworkshavethefollowingadvantages:

1Contentandresourcescanbesharedinthecentralandperipheralareasofthenetwork.Inaclient/servernetwork,contentandresourcescanusuallyonlybesharedinthecentralareaof​​thenetwork.

2.Thenetworkcomposedofpeersiseasytoexpandandmorereliablethanasingleserver.Asingleserverwillbesubjecttoasinglepointoffailure,orwillbecomeabottleneckwhenthenetworkusageishigh.

3.Anetworkcomposedofpeerscanshareprocessorsandintegratecomputingresourcestoperformdistributedcomputingtasks,ratherthanrelyingsolelyonacomputer,suchasasupercomputer.

4.Theusercandirectlyaccessthesharedresourcesonthepeer-to-peercomputer.Thepeersinthenetworkcandirectlysharefilesonthelocalstorageinsteadofsharingonthecentralserver.

Insufficient

1.Affecttheperformanceoftheuser’scomputer

Thecomputerinthepeer-to-peernetworkneedstoundertakeboththeserverandtheworkstationatthesametime,whichmakestheoriginalThesingle-usercomputerofisusedasamulti-usercomputer.Whenlarge-scaledataexchangeiscarriedout,theperformanceofthenetworkwillbegreatlyaffected.

2.Poornetworksecurity

Inapeer-to-peernetwork,resourcesarenotstoredcentrallyinsomecomputers,butarescatteredthroughoutthenetwork,andareManagedbyusers,thereisnoguaranteethatalluserscanprotecttheirresources.Inaddition,themanagementofuseraccountsandpasswordsinapeer-to-peernetworkisalsoanimportantissue.Auserhastomemorizemultiplesetsofaccountsandpasswordstoaccessresourcesindifferentcomputers.

3.Difficultiesinbackingupandrestoringresources

Resourcesinpeer-to-peernetworksarerelativelyscattered,anditismorecomplicatedtobackupandrestoreresourcesinallcomputers.Duetotheabovecharacteristics,peer-to-peernetworksaresuitableforoccasionswithfewusers,smallscale,andlowsecurityperformancerequirements.

Mainmode

P2Pnetworkismainlybasedontwomostbasicmodes,namelycentralizeddirectorymodeandnon-centralizeddirectorymode.

CentralizedDirectoryMode

Thecentralizeddirectory-basedP2PmodeisalsocalledthestructuredP2Pmode.Inthismode,acentralserverissetuptorecordandmanagethesharedinformationresourcesofallnodes.Eachpeernodequeriestheservertoknowwhichnodeinthepeer-to-peernetworkhasthesharedinformationresourcesitneeds.Afterfindingit,obtainsitshostaddress,andthenfurtherrequeststheinformationresourcesitneedsfromthehost.Finally,thehostwillcopyitssharedinformationandsendittotherequestinghost’scentralizeddirectoryP2Pnetwork.

Non-centralizeddirectorymode

TheP2Pmodeofnon-centralizeddirectoryisalsocalledpureP2Pmode.Inthenon-centralizedP2Pmodel,thepeer-to-peernetworkdoesnotneedtosetupacentralservertorecordandmanagethesharedinformationresourcesofallnodes.Toobtainasharedinformationresource,anynodefirstaskswhetheritsneighboringnodehastheresource.Ifaneighboringnodedoesnot,itwillfurtheraskitsneighboringnode(theinquirymessagemustIncludingtheaddressoftheinitialrequestingnode),untilthenodewiththeinformationresourcereceivestheinquiryrequest,thenthisnodewillgiveanaffirmativeresponsetotheinitialrequestingnode(andspecifyitsownaddressatthesametime).Finally,theinitialrequestingnodemakesaresourcerequesttothisnode,andthenodecopiesitssharedinformationandsendsittotheinitialrequestingnode.

Identificationmethod

CurrentcommunicationmodesincludeClient/Server,Brower/ServerandSlave/Master.Forexample,thecorporateLANIntranetandInternetbothuseClient/ServerandBrowser/Serverasthemodel,whiletheearlyhostsystemadoptstheSlave/Mastermodel.Thecharacteristicsofthesemodesare:theyareallbasedontheapplication,theremustbeanapplicationserverinthenetwork,theuser'srequestmustbecompletedthroughtheapplicationserver,andthecommunicationbetweenusersmustalsogothroughtheserver.Inapeer-to-peernetwork,userscancommunicatedirectly,shareresources,andworktogether.

Networkingsteps

1.Determinethenetworktopology.

2.Chooseasuitabletransmissionmedium.

3.Selectnetworkconnectionequipmentaccordingtothetypeoftransmissionmedium,theoperatingspeedofthenetwork,andthecoverageofthenetwork.

4.Hardwareconnection.

5.Installationandconfigurationofnetworksoftware.

6.Setupresourcesharing.

Typesofsoftware

Currently,P2Pnetworkcomputingtechnologyiscontinuouslybeingappliedtomilitary,commerce,governmentaffairs,telecommunications,communicationsandotherfields.Accordingtodifferentspecificapplications,P2Papplicationsoftwarecanberoughlydividedintothefollowingtypes:

1.Filecontentsharinganddownloading,suchasNapster,Gnutella,eDonkey,eMule,Maze,BT,etc.,userscandirectlydownloadfromDownloadoruploadfilesonanyPCwithsimilarsoftwareinstalled,andretrieveandcopysharedfiles.

2.Computingpowerandstoragesharing,suchasSETI@home,Avaki,PopularPower,Netbatch,Farsite,etc.,canbeusedtodistributestorageobjectsonthenetworkorusetheirfreetimeforcollaborativecomputing.

3.CollaborativeprocessingandservicesharingplatformsbasedonP2Ptechnology,suchasJXTA,Magi,Groove,etc.,canbeusedforenterprisemanagement.

4.Instantmessagingtools,includingICQ,QQ,YahooMessenger,MSNMessenger,etc.,multipleuserscancommunicatethroughtext,voiceorfiles,andevencommunicatewithmobilephones.

5.P2Pcommunicationandinformationsharing,suchasSkype,Crowds,OnionRouting,etc.

6.NetworkTVandonlinegamesbasedonP2Ptechnology,suchasBoilingPoint,PPStream,PPLive,QQLive,SopCast,etc.Manycurrentonlinegamesarealsoimplementedthroughpeer-to-peernetworks.

Technicalstandards

Inrecentyears,withtherapidspreadofP2Ptechnology-basedfilesharingsoftwaresuchasNapster,KaZaa,BT,andeMuleontheInternet,P2Ptechnologyhasbeentriggeredbothathomeandabroad.Anewwaveofresearch.

International

Currently,thereisnouniformstandardforinternationalpeer-to-peernetworks.AP2PworkinggroupwasestablishedinAugust2000,withmembersincludingIntel,IBM,andHP.Othermajorobstaclestothedevelopmentofpeer-to-peernetworksincludecopyrightissues,networkbandwidthissues,managementissues,andsecurityissues.Howtoconnectphones,mobilephonesandhomeappliances,industrialequipment,etc.,isalsoaproblemthatneedstobesolvedinpeer-to-peernetworks.

Domestic

DomesticcompanieshavebeenkeepingpacewiththeworldinthefieldofP2Papplicationresearch,andhavedevelopedmanywidelyusedP2Pproducts.Theseproductsaremainlyconcentratedinfilesharinganddownloading,networkstreamingTVandsoon.

• POCO

POCOisChina’sleadingfreemovie,music,animationandothermultimediasharingplatform,andthenumberofpeopleonlineatthesametimeexceedsthenumberWith700,000people,itisChina'slargestmovie,music,andanimationsharingplatform.Itisathird-generationP2Presourceexchangeplatformwithflowcontrolandnocentralserver.POCOprovidestechnologiessuchasmulti-pointtransmissionandresumabletransmissiontoensuretheefficiencyandstabilityofthetransmissionprocess.

• OP

Tothemusic,movies,software,games,pictures,booksandvariousdocumentsyouwant,Thefilecapacityofhundredsofmillionsoffilescanbesharedonlineatanytime.OPintegratesInternetExplorer,WindowsMediaPlayer,RealOnePlayerandACDSee,andisadomesticonlineentertainmentcontentplatform.

• PPLive

PPLiveisasharingsoftwareforlarge-scalelivevideostreamingontheInternet.Itusesthemeshmodeltoeffectivelysolvethebandwidthandloadlimitationofthecurrentnetworkvideo-on-demandservice.Themoreusers,thesmoothertheplayback,andtheoverallservicequalityisgreatlyimproved.

Applicationresearch

P2Pdistributedstoragesystem

P2Pdistributedstoragesystem(filesharinganddownloading)isadatastoragesystemforpeer-to-peernetworks,Itcanprovideefficient,robustandload-balancedfileaccessfunctions.Forstoragesystems,userscareabouttheefficiencyofdatalocation,search,androuting,andsecurityisalsoanimportantfactor.Inmanycases,thecentralizedmethodisnolongersuitableforthislarge-scaledatastoragerequirement,whichrequiresanewsystemtomanagethedatainthesystem.P2Pdistributedstoragesystemistosolvesuchproblems.Thesestudiesincludefullydistributedstoragesystems:Oceanstore,PastandFreeHaven,etc.Amongthem,semi-distributedP2Papplicationsbasedonthesuper-pointstructuresuchasKaZaa,Edonkey,Morpheus,BitTorrent,etc.alsobelongtothecategoryofP2Psharedstorage,andthenumberofusershasincreasedsharply.BothOceanstoreandPastprovideaneffectiveWANstoragemodel.TheirbottomlayerhasestablishedaroutingstrategywithacostupperlimitoflogN.Pastisorientedtoarelativelysimpleandcompactconcept.ItusestheroutingmechanismprovidedbyPastrytotrytouseidlestoragenodesinthenetworktoestablishamorecompletestoragesemantics.FreeHavenhasestablishedadetailedanonymitysystemtopreventpotentialmaliciousattacks.

SharingofP2Pcomputingpower

Inadditiontosharingstoragecapabilities,nodesthatjoinapeer-to-peernetworkcanalsoshareCPUprocessingcapabilities.Therearealreadysomecomputingpowersharingsystemsbasedonpeer-to-peernetworks,suchasSETI@home.SETI@homeisaresearchprojectcarriedoutbytheUniversityofCalifornia,Berkeleytofindalienlife.ItusesP2Ptechnologytoconnectallidlecomputersparticipatingintheresearchprojecttoperformcomplexcalculationstoanalyzeradiosignalsfromplanetsandfindevidencethatotheraliencivilizationsmayexistintheuniverse.Theaveragedailyperformanceofthesecomputersexceedsthehighestcostintheworld.,Thefastestsupercomputer.Thiscomputingpowersharingsystemcanalsobeusedforapplicationsthatrequirelarge-scalecomputingpower,suchasgeneticdatabaseretrievalandpasswordcracking.

Developmenttrend

IntermsofP2Pcollaborativecomputing,domesticenterprisesstartedlate.Therearenotmanyrelatedproducts,andforeigncountriessuchasGroovehavedonealotofworkinthisareaanddevelopedrelativelymatureproducts.Withtheriseoftheconceptofcollaborativecomputing,thedemandforsoftwareinthisareaisshowingatrendofrapidgrowth,anditshouldbeavastocean.Moreover,thistypeofsoftwareisoftengearedtowardsenterpriseandgovernmentusers,soithasbetterprofitmarginsthanfreeP2Pfilesharingsoftware.

IntermsofP2Pstreamingmediatechnology,atpresent,theresearchonstreamingmediatransmissionhasjuststarted,andtherearestillmanyproblemstobesolved.SincethebehaviorofnodesintheP2PstreamingmediasystemisofAd-Hocnature,howtoensurethequalityofserviceofstreamingmediainadynamicsystemenvironmentneedstocombinetheknowledgeofstreamingmedia’sQoSrequirementsandnetworktrafficanalysistostudyhighefficiency,Low-costQoSguaranteemechanism.Researchabledirectionsinclude:theselectionofservicenodes,howtoensurethecontinuityofstreamingmediaserviceswhenanodefails,andthetransmissionschedulingofmultiplesenders.

ThegreatsuccessofSkype,aVoIPproductbasedonP2Ptechnology,hasopenedupanothernewfieldforP2P.RelevantexpertsbelievethatthereshouldbetworoadsforthedevelopmentofVOIP.Oneistherouteoftraditionaltelecomoperators,namely,theestablishmentofanIMSplatformonamanageableIPnetworktodevelopVoIPvoiceservices.Thiskindofnetworkisclosedandmanageable.TheotherisapublicP2PVoIPnetworkbasedontheexistingInternetpublic.Itischaracterizedbyopenness,anyonecanfreelyjoinandleavethenetwork,hasdistributedmanagementandgrowthcapabilities,andanydevicecanbeusedaslongasitsupportsstandardprotocols.Theinterestneedsoftraditionaltelecomoperatorsandtheneedsofusershavebecomeacontradiction,buttheneedsofthemarketandthedevelopmenttrendofVOIPcannotbechanged.Itisstilluncertainwhichpathwillbeadoptedinthefuture.Itdependsondevelopmentandcompetition.TheremaybemanylargecorporatecustomersandgovernmentagenciesthathavespecialrequirementsforsecurityandwilluseVOIPservicesestablishedbytelecomoperators.However,forordinaryusers,P2PVoIPnetworksbasedonthepublicInternetwillbethegeneraltrend.

Tosumup,P2Ptechnologyisinthespringofdevelopment.Killerapplicationsbasedonthistechnologywillcontinuetoemerge.ThesetechnologieswillgreatlyimprovetheappearanceoftheentireITworld,whichcanbesaidtobetheInternet.Anothernewrevolutionintechnology.