计算机网络技术的 历史和新进展.ppt

1、计算机网络技术的历史和新进展,高速计算机信息网络是信息社会的神经和血管体系结构：网络的骨架和神经协议：网络的心脏和血液,主要内容,网络概述Internet的发展和成功经验计算机网络技术的历史回顾国际高速计算机网络研究计划中国高速计算机网络研究计划,WhatisaNetwork?fromendsystempointofview,Networkoffersaservice:moveinformationbird,fire,messenger,truck,telegraph,telephone,Internetanotherexample,transportationservice:moveobje

2、ctshorse,train,truck,airplane.Whatdistinguishdifferenttypesofnetworks?TheservicestheyprovideWhatdistinguishtheservices?latencybandwidthlossratenumberofendsystemsserviceinterface(howtoinvoke?)otherdetailsreliability,unicastvs.multicast,real-time,messagevs.byte.,WhatisaNetwork?InfrastructureCentricVie

3、w,ElectronsandphotonsascommunicationmediumLinks:fiber,copper,satellite,Switches:mechanical/electronic/optical,crossbar/BanyanProtocols:TCP/IP,ATM,MPLS,SONET,Ethernet,PPP,X.25,FrameRelay,AppleTalk,IPX,SNAFunctionalities:routing,errorcontrol,congestioncontrol,QualityofService(QoS)Applications:FTP,WEB,

4、Xwindows,.,TypesofNetworks,GeographicaldistanceLocalAreaNetworks(LAN):Ethernet,Tokenring,FDDIMetropolitanAreaNetworks(MAN):DQDB,SMDSWideAreaNetworks(WAN):X.25,ATM,framerelayInformationtypedatanetworksvs.telecommunicationnetworksApplicationtypespecialpurposenetworks:airlinereservationnetwork,bankingn

5、etwork,creditcardnetwork,telephonygeneralpurposenetwork:Internet,TypesofNetworks,Righttouseprivate:enterprisenetworkspublic:telephonynetwork,InternetOwnershipofprotocolsproprietary:SNAopen:IPTechnologiesterrestrialvs.satellitewiredvs.wirelessProtocolsIP,AppleTalk,SNA,计算机网络发展历史回顾,七十年代的计算机网络X.25分组交换网：

6、各国的电信部门建设运行各种专用的网络体系结构：SNA，DNAInternet的前身ARPANET进行实验运行八十年代的计算机网络标准化计算机网络体系结构：OSI局域网络LAN技术空前发展建成NSFNET，Internet初具规模九十年代的计算机网络Internet空前发展Web技术在Internet/Intranet得到广泛应用,主要内容,网络概述Internet的发展和成功经验计算机网络技术的历史回顾国际高速计算机网络研究计划中国高速计算机网络研究计划,TheInternet,Globalscale,generalpurpose,heterogeneous-technologies,publ

7、ic,computernetworkInternetProtocolopenstandard:InternetEngineeringTaskForce(IETF)asstandardbodytechnicalbasisforothertypesofnetworksIntranet:enterpriseIPnetworkDevelopedbytheresearchcommunity,HistoryoftheInternet,70s:startedasaresearchproject,56kbps,100computers80-83:ARPANETandMILNETsplit,85-86:NSFb

8、uildsNSFNETasbackbone,links6Supercomputercenters,1.5Mbps,10,000computers87-90:linkregionalnetworks,NSI(NASA),ESNet(DOE),DARTnet,TWBNet(DARPA),100,000computers90-92:NSFNETmovesto45Mbps,16mid-levelnetworks94:NSFbackbonedismantled,multipleprivatebackbonesToday:backbonesrunat2.5/10Gbps,10smillionscomput

9、ersin150countries,GrowthoftheInternet,NumberofHostsontheInternet:Aug.1981213Oct.19841,024Dec.198728,174Oct.1990313,000Oct.19932,056,000Apr.19955,706,000Jul.199719,540,000Jul.200093,047,785,RecentGrowth(1991-2000),Internet发展规模和趋势,Internet的发展速度是历史上发展最快的一种技术以商业化后达到5000万用户为例电视用了13年，收音机用了38年，电话更长Internet

10、从商业化后达到5000万用户用了4年时间Internet正在以超过摩尔定理的速度发展,网络时代的三大基本定律,摩尔定律:CPU性能18个月翻番,10年100倍。所有电子系统（包括电子通信系统，计算机）都适用,光纤定律：超摩尔定律，骨干网带宽9个月翻番，10年10000倍。带宽需求呈超高速增长的趋势,迈特卡尔夫定律:联网定律，网络价值随用户数平方成正比。未联网设备增加N倍，效率增加N倍。联网设备增加N倍，效率增加N2倍,网络带宽与CPU性能,光纤容量,高水平大容量光纤传输试验系统,Data(Still)OvertakingVoice,0,RelativeCapacity(%),Voice,Dat

11、a,Source:MCI(VintCerf),InternationaldatatrafficalreadyexceedsinternationalvoicefromAustraliaandScandinavia.,2000,1998,1996,IP(Still)ConqueringData,AllOther,IPX,TCP/IP,TrafficRatios,Source:Gartner1997,100%,90%,80%,70%,60%,50%,40%,30%,20%,10%,0%,RelativeUserPopulation,8%,17%,39%,27%,7%,2%,13%,18%,23%,

12、23%,16%,7%,14%,17%,12%,15%,28%,14%,Internet(Still)GoingInteractive,ToTransactionalPages(Red)andAudio/VideoContent(Purple),100%,80%,60%,40%,20%,0%,2000,1998,1996,Source:TheYankeeGroup,1996,Apps(Always)DrivingCapacity,SimpleVideo,Multimedia,Browsing,PCMVoice,IP,PCS,E-Mail,FileTransfer,Paging,VideoConf

13、erencing,MPEG1NTSCVideo,Telnet,VoIP,ISDN,FrameRelay,ATM/POS,T3/E3,T1/E1,NewModem,WirelessWAN,OldModem,.004,.0192,.0288,.128,1.5,3,155,Mb/s,MinimumBandwidthforApplicationperUser,VirtualReality,MedicalImaging,Data/Voice/VideoTransportConvergence,高速信息网络的发展方向：通信与计算聚合,通信和计算技术的聚合改变了各自的原有特征高速信息网络体系结构的发展趋势分

14、层结构；分布控制、管理和安全机制分层结构比特路层服务层应用层,高速信息网络的体系结构,比特路层主干网传输技术：SDH/SONET，光纤主干网交换技术：IPoverSDH或光纤，GbE，支持IPv6端系统接入技术：LAN；ADSL、FTTH、HFC服务层（支撑技术）全球统一的地址、域名；安全的系统管理和访问控制Browser/Server计算模式，支持Data,Voice,Video以Java为代表的网络编程语言应用层（用户功能）用户用户（立即响应，可适当延迟）用户服务器（立即响应，可适当延迟）,ATM,SDH/SONET,IP,Optical,IPTransportAlternatives,B

15、-ISDN,IPoverATM,IPoverSDH/SONET,IPoverOptical,Long-TermWinners,IP,ATM,Optical,IP,SDH/SONET,Optical,IP,Optical,Multiplexing,Protection,andManagementatEveryLayer.,EliminatingLayersLowersCosts.,WhoisWhoontheInternet?,InternetEngineeringTaskForce(IETF):TheIETFistheprotocolengineeringanddevelopmentarmoft

16、heInternet.Subdividedintomanyworkinggroups,whichspecifyRequestForCommentsorRFCs.IRTF(InternetResearchTaskForce):TheInternetResearchTaskForceisacomposedofanumberoffocused,long-termandsmallResearchGroups.InternetArchitectureBoard(IAB):TheIABisresponsiblefordefiningtheoverallarchitectureoftheInternet,p

17、rovidingguidanceandbroaddirectiontotheIETF.TheInternetEngineeringSteeringGroup(IESG):TheIESGisresponsiblefortechnicalmanagementofIETFactivitiesandtheInternetstandardsprocess.Standards.ComposedoftheAreaDirectorsoftheIETFworkinggroups.,InternetStandardizationProcess,AllstandardsoftheInternetarepublish

18、edasRFC(RequestforComments).ButnotallRFCsareInternetStandards!available:Atypical(butnotonly)wayofstandardizationis:InternetDraftsRFCProposedStandardDraftStandard(requires2workingimplementation)InternetStandard(declaredbyIAB)DavidClark,MIT,1992:Wereject:kings,presidents,andvoting.We

19、believein:roughconsensusandrunningcode.”,ServicesProvidedbytheInternet,Sharedaccesstocomputingresourcestelnet(1970s)Sharedaccesstodata/filesFTP,NFS,AFS(1980s)Communicationmediumoverwhichpeopleinteractemail(1980s),on-linechatrooms,instantmessaging(1990s)audio,video(1990s)replacingtelephonenetwork?Ame

20、diumforinformationdisseminationUSENET(1980s)WWW(1990s)replacingnewspaper,magazine?audio,video(1990s)replacingradio,CD,TV?,TodaysVision,Everythingisdigital:voice,video,music,picturesEverythingison-line:bankstatement,medicalrecord,books,airlineschedule,weather,highwaytraffic,toaster,refrigeratorEveryo

21、neisconnected:doctor,teacher,broker,mother,son,friends,enemies,WhatisNext?,ElectroniccommercevirtualenterpriseInternetentertainmentinteractivesitcomWorldasasmallvillagecommunityorganizedaccordingtointerestsenhancedunderstandingamongdiversegroupsElectronicdemocracylittlepeoplecanvoicetheiropinionstot

22、hewholeworldbridgethegapbetweeninformationhavesandhavenosElectronicterrorismhackercanbringthewholeworldtoitsknee,IndustrialPlayers,Telephonecompaniesownlong-haulandaccesscommunicationlinks,customersCablecompaniesownaccesslinksWireless/SatellitecompaniesalternativecommunicationlinksUtilitycompanies:p

23、ower,water,railwayownrightofwaytolaydownmorewiresMediumcompaniesowncontentInternetServiceProvidersEquipmentcompaniesswitches/routers,chips,optics,computersSoftwarecompanies,Backbone,ISP,ISP,InternetPhysicalInfrastructure,ResidentialAccessModemDSLCablemodemSatelliteLAN,Enterprise/ISPaccess,Backbonetr

24、ansmissionT1/T3,DS-1DS-3OC-3,OC-12ATMvs.SONET,vs.WDM,CampusnetworkEthernet,ATMInternetServiceProvidersaccess,regional,backbonePointofPresence(POP)NetworkAccessPoint(NAP),LinksforLongHaulTransmission,TypesoflinksT1/DS1:1.544MbpsT3/DS3:44.736MbpsSTS-1/OC-1:51.850MbpsSTS-3/OC-3:155.2MbpsSTS-12/OC-12:62

25、2.080MbpsSTS-48/OC-48:2.488GbpsSTS-192/OC-192:9.953GbpsHigherlevelsofservicesofferedcommerciallyFrameRelayATM,PossibilitiesIPoverSDH/SONETIPoverATMIPoverFrameRelayIPoverWDM,Internet的成功经验,有远见的政府不断支持：1969有风险的企业参与和投入：NFS：MCI、IBMvBNS：MCI；Abilene:Qwest，CISCO联合协作的开放式研究：IETF/RFC教育和科研的示范网络为起点具有实验物理学的研究特点ARP

26、Anet、NSF、ANS、vBNS简单实用的技术路线：TCP/IP,Researchand,Development,Commercialization,Partnerships,Privatization,NSFNET,Internet2,Abilene,vBNS,AdvancedUSGovtNetworks,ARPAnet,gigabit,testbeds,Active,Nets,wireless,WDM,SprintLink,InternetMCI,USGovt,Networks,ANS,Interoperable,HighPerformance,Researcholdroutingent

27、riestimeoutanddeletedForwardpacketsASAPnotnecessarilyalongshortestpathsallthetimeLearningfailuresexpectedtobeextremeexceptionsahumanconfigured,tightlycontrolledsystemBaranproposalareliablesystembuiltoutofsimple,unreliablepartsanadaptivesystemthatadjustsitselftochangesautomaticallySmartendstofixtrans

28、missionerrors,OneRealizationofBaransDesing:theInternet,interconnectingheterogeneoussubnetstwobasicfunctionalities:globallyuniqueaddressesdatagramdeliveryfromsourcestodestinationsviadynamicroutingClaim:simple,flexible,scalable,androbust,IPsviewoftheworld,IP,Allkindsofsubnettechnologies,allkindsofappl

29、ications,allkindsoftransportprotocols,Datagramsasthebasicbuildingblock:SystemSimplicity,EachpacketcarriesitsownaddressOneroutingtableservesalltrafficAnenablertotheexplosivegrowththesimpler,thefewerchancestogowrongthesimpler,theeasiertogrowtherequirementofleastcommonnetworkfunctionalitymaximizesthenu

30、mberofusablenetworks,Datagramsasthebasicbuildingblock:Flexibility,“runsoveranything”IPstartedwithARPANET,PRNET,SATNET;alllonggonetodayIPrunsover100MborGb/sEthernet,FDDI,FrameRelay,ATM,SONET,DWDMSupportsalldifferentapplicationsusedtobetelnet,ftp,emailonlynowaudio,video,web,e-commerce,online-education

31、,Whatwillthefuturebring?Thebestbetwouldbetostayflexible,Datagramsasthebasicbuildingblock:Scalability,ToscalethesystemmustbeabletogracefullyhandlethegrowthinthetotalnumberofendsystemsthegrowthintrafficvolumethegrowthinnetworksizelargerroutingtablesMorefrequentchanges,WithIP,“thenetworkknowsnothingabo

32、utindividualendapplications;endapplicationsknownothingaboutnetworkinternals”VanJacobsonmadeitpossibletoaggregateroutingtableentriesaccordingtoscalingneed,Datagramsasthebasicbuildingblock:Robustness,self-adaptivenatureofdynamicroutingfacilitatedthegrowthdynamicroutinganddatagramdeliverygohand-in-hand

33、periodicroutingupdates:“areyoustillthere”silentassumption:existingpartsmayfail,newpartsmayappearanytimechangesconsideredthenormratherthanexceptionstradesoffoptimallinkusage(e.g.headeroverhead,updateoverhead)forsystemrobustness,“Unintendedconsequence”?,InacasualconversationNoelChiappasaid,withoutDoDs

34、Internetresearchinitiative“Perhapswedhavediscoveredcomputernetworkseventually,butIhavenoideawhen;.Itsalsounclearifwedhavethekindofnetworkwedoifithadntbeenintendedforsuchause.,“Aspiritofintenserobustness,andtheabilitytokeepgoingnomatterwhat,hasbeenpartoftheInternetethicsincedayone,anditisdueinparttot

35、herathersevereoperationenvironmentforwhichitwasoriginallyintended.ThisextremelymonolithicnatureoftheInternetisoneofthethingswhichismakingithostiletocontrol,andperhapsthatisinsomepartduetotheoriginalgoalsofthenetwork.”,“Whyatoughersystem?”,thingsdogowrongfromtimetotime,despiteallthehonesteffortstopre

36、ventthemHaveaguessonhowoftennetworkoutagehappens?Getworseasthesystemgrowslarger“Whatsortofchangeswouldbehelpfulinnextgenerationnetworks?Ofcoursehigherdatarateandlowercostaredesirable,butofallparametersIwouldoptforgreateremphasisonrobustness.”PaulBaran,1977,HowtheInternetlooksliketoday,Nolongerthesam

37、eas20yearsagoAlotbiggerAlotmoreusersAlotmoreuseful,alotmorevaluablelessrobust,lessadaptive,andlessconnected.EffectivelywewereoutofIPv4addressspacesomeyearsagomostusersareconnectedviaNetworkAddressTranslator(NAT)now,Latercomer,NAT:afeatureoraproblem?,“NATsolvestheaddressexhaustionproblem,andevenbring

38、sabenefitofmorecontrol,moresecurity”NATsbrokeanumberofexistingprotocolsandapplicationswhichwerebuiltontheassumptionofIPaddressbeinggloballyuniqueLostabilitytosupportnewpeer-to-peerapplicationsend-to-endpacketdeliverypathbecomesaconcatenationofNATboxeseffectivelyavirtualcircuit,Internet,Factsversusfa

39、irystories,Overtimetheoriginalarchitecturehaseroded.Entropy(delay)thathappenstoalllargesystems?TorestoreIParchitecture:movingtoIPv6fixestheaddressexhaustionproblemWhyIPv6hasnotbeenwidelydeployed:a“wedonotneedit”groupgoingaroundtellingfairystoriesNATlovers:NGI的进展：NGI实现计划（1998年2月）NGI

40、概念文章（1997年7月）,NGI目标1：先进网络技术的实验研究,网络工程规划和模拟；监视；集成；数据传递；网络管理；动态和自适应的网络服务质量（端到端）服务质量体系结构；允许控制，计费和优先权；可观察和控制的API；DrillDown技术安全用户用安全和公平的方法服务网络资源；优越的网络管理；网络内部的监视；游动/远程访问；公钥基础设施,NGI目标2：下一代网络测试床,开发下一代网络测试床，用比现在Internet快100倍以上的速度连接至少100个大学和国家研究实验室以1997年1.54Mbps计，10个连接点速度达到比现在Internet快1000倍端到端连接速度达到100Mbps1Gb

41、psNGI目标2包括高性能连接：开发广域网结构，用100+Mbps速度连接100个广域点下一代网络技术和超高性能连接：开发超高速交换和传输技术，用1+Gbps速度连接10个以上的局域点主要策略：协调建立一个高性能的协作网络利用现有的网络试验床：vBNS,ESnet,NREN评价标准：连接点的数量，端到端的性能支持目标1的研究，支持目标3的应用,NGI目标3：革命性的网络应用,开发今天Internet没有，对国家重要的网络应用健康保健：远程医疗、紧急医疗响应支持教育：远程教育、数字图书馆科学研究：能源、地理系统、气象、生物国家安全：高性能全球通信、先进的信息传播环境：监测、预测、警告、响应政府：

42、传递政府服务和信息给公民和企业突发事件：灾难响应、危机管理设计和制造：制造工程主要策略：重点研究基础性应用分布式计算应用、协同性应用,vBNSCooperativeAgreement,CompetitivelyawardedinApril1995EstablishedbytheNSFinordertoensuretheavailabilityofhighperformancenetworkingresourcesfortheUSResearch&EducationcommunityfostertheadvancementofnetworkingtechnologyNSFcontributes:

43、programmanagementandfundingMCIcontributes:bandwidth,equipment,andengineering,SanFrancisco,NationalCenterforAtmosphericResearch,SanDiegoSupercomputerCenter,Houston,Denver,AmeritechNAP,Chicago,NationalCenterforSupercomputingApplications,Cleveland,Perryman,MD,SprintNAP,MFSNAP,PittsburghSupercomputingCe

44、nter,LosAngeles,A,Atlanta,A,NewYorkCity,vBNSBackboneNetworkMap,Boston,Washington,DC,Seattle,A,A,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,J,J,AscendGRF400Cisco7507JuniperM40FOREASX-1000NAP,A,C,DS-3OC-3COC-12COC-48,J,SanFrancisco,NationalCenterforAtmosphericResearch,SanDiegoSupercomputerCenter,Houston,Denv

45、er,Chicago,NationalCenterforSupercomputingApplications,Cleveland,Perryman,MD,PittsburghSupercomputingCenter,LosAngeles,Atlanta,NewYorkCity,vBNSBackbone3Q99,Boston,Washington,DC,Seattle,Internet2,UCAID（120多个大学会员）的一项研究计划UniversityCorporationforAdvancedInternetDevelopment形成大学试验网，开发下一代Internet技术和应用IPv6，

46、Multicasting，QOS以竞争方式得到NGI计划的经费支持NGI是政府计划，Internet2是大学合作计划相互补充，相互依靠Internet2和NGI的合作范围NSF支持的vBNSInternet2将建立用于地区连接的gigaPoPInternet2的许多网络应用开发由NGI支持,AdvancedInternetBenefits,RichercontentthroughhigherbandwidthVideo,audioVirtualrealityDynamicnotstaticMoreinteractivityviaminimaldelayReliablecontentdelive

47、rythroughqualityofservicemodel,Internet2Applications,Deliverqualitativeandquantitativeimprovementsintheconductof:ResearchTeachingLearningRequireadvancednetworking,VirtualLaboratories,InteractiveresearchandinstructionReal-timeaccesstoremotescientificinstruments,ImagescourtesyoftheUniversityofMichigan

48、,VirtualLaboratories,Real-timeaccesstoremoteinstrumentsUniversityofPittsburgh,PittsburghSupercomputingCenter3-DBrainMapping,DigitalLibraries,VideoandaudioIndianaUniversityVariationsProject,DistributedComputation,Multi-sitedatabasesOldDominionUniversityChesapeakeBaySimulation,ImagecourtesyofOldDomini

49、onUniversity,Teleimmersion,SharedvirtualrealityUniversityofIllinoisatChicagoVirtualTemporalBone,ImagescourtesyUnivofIllinois-Chicago,Abilene,Projectannounced14April1998byVPGoreMostadvancedandfarreachingresearchandeducationnetworkintheworldsupportadvancedresearchapplicationsintegratedadvancednetworks

50、ervicesDevelopedbyUCAIDQwest,NortelandCiscocorporatepartnersAdvancednativeIPbackbonenetworkavailabletouniversitiesparticipatinginUCAIDsInternet2project,AbileneCharacteristics,2.4Gbps(OC48)amonggigaPoPs,increasingto9.6Gbps(OC192)Connectionsat622Mbps(OC12)or155Mbps(OC3)IPoverSonettechnologyAccessPoPsv

51、eryclosetoalmostalloftheanticipateduniversitygigaPoPs,AbileneSchedule,Fall1998:Demonstratednetworkatmembermeeting,inpre-productionatseveraluniversities,connectedtoChicagoswitchforSTARTAPJanurary1999:AbileneinserviceByDecember1999:around65institutionsconnected,TheTransPACNetwork,Thenetworkisbasedona70MbpsVBR-nrtATMinternationalconnectionbetweentheSTARTAPinChicagoandtheAPANTokyoexchangepoint.TheunderlyingATMserviceprovidedbyAT&T/KDD.TransPACprovidesATMandIP-layeruserservices.APAN-TransPAC