計算機網(wǎng)絡(luò)Internet歷史現(xiàn)狀與未來

1、計算機網(wǎng)絡(luò)（計算機網(wǎng)絡(luò)（InternetInternet）歷史，現(xiàn)狀與未來歷史，現(xiàn)狀與未來計算機網(wǎng)絡(luò)計算機網(wǎng)絡(luò)nTransportation service: move objectsuhorse, train, truck, airplane .nCommunication network: move informationubird, fire, telegraph, telephone, Internet nCommunication networks can be classified based on the way in which the nodes exchange infor

2、mation:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication Network 廣播，電視廣播，電視Circuit-SwitchedCommunication Network 電話電話Packet-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit NetworkInternetThe example n通話在通話在 A 到到 B (經(jīng)過四個交換機經(jīng)過四個交換

3、機) 的連接上進行的連接上進行n思考：電話交換對于計算機是否適合？思考：電話交換對于計算機是否適合？u 效率效率/成本成本u 應用實時應用實時(交換機交換機交換機交換機交換機交換機交換機交換機用戶線用戶線用戶線用戶線中繼線中繼線中繼線中繼線BDCACircuit Switching （電路交換電路交換-電話）電話）nA node (switch) in a circuit switching networkincoming linksoutgoing linksNodeCircuit Switching: Multiplexing/DemultiplexingnTime divided in

4、frames and frames divided in slotsnRelative slot position inside a frame determines which conversation the data belongs tonNeeds synchronization between sender and receivernIn case of non-permanent conversationsuNeeds to dynamic bind a slot to a conservationuHow to do this?Timing in Circuit Switchin

5、gpropagation delay between Host 1 and Node 1propagation delay between Host 2 and Node 1DATACircuit Circuit Establishment Establishment Data Data Transmission Transmission Circuit Circuit Termination Termination Host 1Host 2Node 1Node 2processing delay at Node 1報文報文11010001101010101101010111000100110

6、10010假定這個報文較長假定這個報文較長不便于傳輸不便于傳輸Packet Switching （分組分組/包交換）包交換） 1961 Computer networks self-development-packet switchingz分組交換網(wǎng)以分組交換網(wǎng)以“分組分組”( (也稱也稱 包包) )作為數(shù)據(jù)傳輸單元作為數(shù)據(jù)傳輸單元z依次依次把各分組發(fā)送到接收端（假定接收端在左邊）。把各分組發(fā)送到接收端（假定接收端在左邊）。數(shù)數(shù) 據(jù)據(jù)首部首部分組分組 1數(shù)數(shù) 據(jù)據(jù)首部首部分組分組 2數(shù)數(shù) 據(jù)據(jù)首部首部分組分組 3Computer networks development-packet swit

7、ching數(shù)數(shù) 據(jù)據(jù)數(shù)數(shù) 據(jù)據(jù)數(shù)數(shù) 據(jù)據(jù)報文報文1101000110101010110101011100010011010010Packet Switching （分組分組/包交換）包交換） 1961 nData are sent as formatted bit-sequences, so-called packetsnPackets have the following structure:FHeader and Trailer carry control information (e.g., destination address, check sum)nEach packet is p

8、assed through the network from node to node along some path (Routing)nAt each node the entire packet is received, stored briefly, and then forwarded to the next node (Store-and-Forward Networks)nTypically no capacity is allocated for packetsHeaderDataTrailerRouter CongestedRouter ARouter BRouter CRo

9、uter DRouter EPacket Switching - ExampleRouter FTiming of Datagram Packet SwitchingPacket 3Packet 3Packet 1Packet 2Packet 1Packet 2Packet 1Packet 2Packet 3processing delay of Packet 1 at Node 2Host 1Host 2Node 1Node 2propagationdelay betweenHost 1 and Node 2 transmission time of Packet 1at Host 1Pac

10、ket Switching （分組分組/包交換）包交換） 1961 incoming linksoutgoing linksNodeMemoryPacket Switching: Multiplexing/DemultiplexingnData from any conversation can be transmitted at any given timenHow to tell them apart?uUse meta-data (header) to describe datanDatagram Packet SwitchinguEach packet is independently

11、 switchedFEach packet header contains destination addressuNo resources are pre-allocated (reserved) in advanceuExample: IP networksModel: Queuing System Queuing System Queue Server Customers Response Time vs. Arrivals1WWaiting vs. Utilization00.00.2500.811.2W(sec) Internet 歷史歷史(1

12、) Sep69 1st IMP in UCLA, Oct69 2nd IMP in SRI Internet 之父之父- L. Kleinrock1999 1969 History of the Internet (2) History of the Internet (3)nLOGIN from UCLA to SRI CLAnWe sent an “L” - did you get the “L”? YEP! n We sent a “O” - did you get the “O”? YEP! nWe sent an “G” - did you get the “G”? Crash!Hi

13、story of the Internet (4)n1961-1972: Early packet-switching principlesn1961: Kleinrock queueing theory shows effectiveness of packet-switchingn1964: Baran - packet-switching in military netsn1967: ARPAnet conceived by Advanced Research Projects Agency (Licklider, Roberts)n1969: first ARPAnet node op

14、erationaln1972: ARPAnet has 15 nodesuARPAnet demonstrated publiclyuNCP (Network Control Protocol) first host-host protocolufirst e-mail programHistory of the Internet (5)n1972-1980: Internetworking, research networksn1970:ALOHAnet satellite network in Hawaii (Abramson)n1973:Metcalfes PhD thesis prop

15、oses Ethernetn1974:Cerf and Kahn - 2004 A.M. Turing Award -define todays Internet architectureuminimalism, autonomy no internal changes required to interconnect networksubest effort service modelustateless routersudecentralized controln1979:ARPAnet has 200 nodes, 56 kbps nLate 70s: proprietary archi

16、tectures: DECnet, SNA nLate 70s: switching fixed length packets (- ATM)History of the Internet (6)n1980s new protocols, a proliferation of netn1983:deployment of TCP/IP. (Critical separation; Cohen)n1982:SMTP e-mail protocol definedn1983:DNS defined for name-to-IP-address translationnmid-1980s: IETF

17、 activen1985:FTP protocol definedn1988:TCP congestion controlnnew national networks: Csnet, BITnet, Minitel , NSFnet (1.5 Mbps,10,000 computers), NSI (NASA), ESNet(DOE), DARTnet, TWBNet (DARPA), n100,000 hosts connected to confederation of networksHistory of the Internet (7)n1990s: commercialization

18、, the WWWnEarly 1990s: ARPAnet decommissionedn1991: NSFnet (45 Mbps) - commercial use of NSF (decommissioned, 1995)nLate 1990s:umultiple private backbonesu50 million computers on Internetu100 million+ usersubackbone links running at 1 Gbps nEarly 1990s: WWWuhypertext Bush 1945, Nelson 1960suHTML, ht

19、tp: Berners-Leeu1994: Mosaic, later Netscapeulate 1990s: commercialization of the WWWInternet 提供的服務提供的服務nShared access to computing resourcesutelnet (1970s)nShared access to data / filesuFTP, NFS, AFS (1980s)nCommunication medium over which people interactuemail (1980s), on-line chat / messaging (19

20、90s)uaudio, video (1990s)Freplacing telephone network?nA medium for information disseminationuUSENET (1980s)uWWW (1990s)Freplacing newspaper, magazine?uaudio, video (1990s)Freplacing radio, CD, TV?Internet Physical InfrastructureClassification by Coverage模型模型, 協(xié)議協(xié)議, 分層分層Protocol ArchitectureDont Nee

21、d All Layers EverywhereProtocol Data Unit - PDUsNetwork Components (Examples)FibersCoaxial CableLinksInterfacesSwitches/routersEthernet cardWireless cardLarge routerTelephoneswitchGrowth of the InternetInternet 在中國在中國趨勢趨勢: : 網(wǎng)絡(luò)時代網(wǎng)絡(luò)時代n每一件事務都是數(shù)字的每一件事務都是數(shù)字的: : 聲音聲音, , 視頻視頻, , 音樂音樂, , 畫畫片片n每一件事務都是在線的每一件

22、事務都是在線的: : 銀行銀行, , 醫(yī)療醫(yī)療, , 航空航空, , 天天氣情況氣情況, , 公路交通公路交通, , n每個人之間都是相互聯(lián)系的每個人之間都是相互聯(lián)系的: :醫(yī)生醫(yī)生, ,教師教師, ,經(jīng)濟人經(jīng)濟人, ,母親母親, ,兒子兒子, , 朋友朋友, , 敵人敵人n實現(xiàn)家庭實現(xiàn)家庭u教育，教育， 辦公，辦公， 購物，購物， 娛樂娛樂/ /網(wǎng)上娛樂網(wǎng)上娛樂n虛擬工作場所虛擬工作場所u20002000年，美國有五千五百萬人實現(xiàn)遠程工作年，美國有五千五百萬人實現(xiàn)遠程工作n網(wǎng)絡(luò)制造網(wǎng)絡(luò)制造/ /電子商務電子商務趨勢趨勢: : 網(wǎng)絡(luò)時代網(wǎng)絡(luò)時代n 計算機集成制造系統(tǒng)計算機集成制造系統(tǒng)/先進制造

23、先進制造/信息化信息化CIMS (Computer Integrated Manufacturing)，包括市場分析、產(chǎn)品設(shè)計、加工，包括市場分析、產(chǎn)品設(shè)計、加工制造、經(jīng)營管理及售后服務的全部經(jīng)營活動，制造、經(jīng)營管理及售后服務的全部經(jīng)營活動，處理處理產(chǎn)品可以看作數(shù)據(jù)的物質(zhì)表現(xiàn)產(chǎn)品可以看作數(shù)據(jù)的物質(zhì)表現(xiàn).目標目標-提高競爭力（提高競爭力（CIMS-Internet）7070年代前年代前 降低勞動成本降低勞動成本降低產(chǎn)品成本降低產(chǎn)品成本7070年代年代提高企業(yè)整體效益提高企業(yè)整體效益降低產(chǎn)品成本降低產(chǎn)品成本 提出提出CIMSCIMS8080年代年代TQCSTQCSCIMSCIMS推廣應用推廣應用9

24、090年代年代新產(chǎn)品開發(fā)，信息、知識新產(chǎn)品開發(fā)，信息、知識CIMSCIMS發(fā)展發(fā)展20002000年代年代核心：服務核心：服務/ /用戶用戶范圍：全球企業(yè)間范圍：全球企業(yè)間/ /供應鏈供應鏈資源：信息、知識（無時空）資源：信息、知識（無時空）/ /電子商務電子商務網(wǎng)絡(luò)制造網(wǎng)絡(luò)制造電子商務電子商務n信息技術(shù)和信息技術(shù)和InternetInternet引發(fā)的商務過程的變化引發(fā)的商務過程的變化n利用以利用以InternetInternet為核心的信息技術(shù)，進行商務為核心的信息技術(shù)，進行商務活動和企業(yè)資源管理活動和企業(yè)資源管理nCIMSCIMS是企業(yè)實施電子商務的基礎(chǔ)是企業(yè)實施電子商務的基礎(chǔ)n企業(yè)實施

25、電子商務是企業(yè)實施電子商務是CIMSCIMS發(fā)展的主要標志和主發(fā)展的主要標志和主要內(nèi)容要內(nèi)容競爭環(huán)境改變競爭環(huán)境改變核心核心 產(chǎn)品競爭產(chǎn)品競爭電子商務產(chǎn)生背景電子商務產(chǎn)生背景服務競爭服務競爭范圍范圍 單個企業(yè)單個企業(yè)全球多企業(yè)全球多企業(yè)資源資源 人、財、物人、財、物信息、知識信息、知識管理重心遷移管理重心遷移生產(chǎn)管理生產(chǎn)管理供應供應/營銷鏈管理營銷鏈管理集中內(nèi)部資源集中內(nèi)部資源整合外部資源整合外部資源離散管理離散管理集約管理集約管理商務模式轉(zhuǎn)化商務模式轉(zhuǎn)化文秘型管理文秘型管理關(guān)注后臺（企業(yè)內(nèi)部）關(guān)注后臺（企業(yè)內(nèi)部）關(guān)注業(yè)務記錄（報表）關(guān)注業(yè)務記錄（報表）地區(qū)性地區(qū)性推銷產(chǎn)品為中心推銷產(chǎn)品為中心

26、（賣方市場）（賣方市場）自我服務型管理自我服務型管理關(guān)注前端（客戶關(guān)系）關(guān)注前端（客戶關(guān)系）要求商業(yè)智能（分析）要求商業(yè)智能（分析）全球化全球化客戶為中心客戶為中心（買方市場）（買方市場）傳統(tǒng)商務傳統(tǒng)商務電子商務電子商務客戶客戶供應商供應商合作伙伴合作伙伴網(wǎng)絡(luò)智能網(wǎng)絡(luò)智能市場營銷市場營銷產(chǎn)品產(chǎn)品/服務服務銷售銷售產(chǎn)品制造產(chǎn)品制造服務服務/支持支持e企業(yè)的業(yè)務體系結(jié)構(gòu)企業(yè)的業(yè)務體系結(jié)構(gòu)協(xié)同產(chǎn)品商務協(xié)同產(chǎn)品商務( CPC)制制 造造 規(guī)規(guī) 劃劃 方方 案案制制 造造 規(guī)規(guī) 劃劃 方方 案案生生 產(chǎn)產(chǎn) 管管 理理 方方 案案生生 產(chǎn)產(chǎn) 管管 理理 方方 案案銷銷 售售 和和 輸輸 送送 方方 案案銷

27、銷 售售 和和 輸輸 送送 方方 案案維維 護護 和和 售售 后后 服服 務務 方方 案案維維 護護 和和 售售 后后 服服 務務 方方 案案營營 銷銷 方方 案案營營 銷銷 方方 案案產(chǎn)產(chǎn) 品品 開開 發(fā)發(fā) 方方 案案產(chǎn)產(chǎn) 品品 開開 發(fā)發(fā) 方方 案案零零 部部 件件 管管 理理 方方 案案零零 部部 件件 管管 理理 方方 案案供供 應應 商商 方方 案案供供 應應 商商 方方 案案制制 造造 規(guī)規(guī) 劃劃 方方 案案制制 造造 規(guī)規(guī) 劃劃 方方 案案生生 產(chǎn)產(chǎn) 管管 理理 方方 案案生生 產(chǎn)產(chǎn) 管管 理理 方方 案案銷銷 售售 和和 輸輸 送送 方方 案案銷銷 售售 和和 輸輸 送送 方方

28、 案案維維 護護 和和 售售 后后 服服 務務 方方 案案維維 護護 和和 售售 后后 服服 務務 方方 案案營營 銷銷 方方 案案營營 銷銷 方方 案案產(chǎn)產(chǎn) 品品 開開 發(fā)發(fā) 方方 案案產(chǎn)產(chǎn) 品品 開開 發(fā)發(fā) 方方 案案零零 部部 件件 管管 理理 方方 案案零零 部部 件件 管管 理理 方方 案案供供 應應 商商 方方 案案供供 應應 商商 方方 案案Internet/Intranet制 造 企 業(yè)用 戶供 應 商 企業(yè)的發(fā)展趨勢企業(yè)的發(fā)展趨勢部門之間的障礙部門之間的障礙 業(yè)務過業(yè)務過 程重組程重組 IDS Sheer業(yè)務流程業(yè)務流程2000年以后年以后電子商電子商務工程務工程 IDS S

29、heer企業(yè)之間的障礙企業(yè)之間的障礙網(wǎng)絡(luò)制造網(wǎng)絡(luò)制造-電子商務電子商務網(wǎng)絡(luò)發(fā)展趨勢網(wǎng)絡(luò)發(fā)展趨勢趨勢趨勢: 融合融合Trend:趨勢趨勢: : 更快的傳輸介質(zhì)更快的傳輸介質(zhì)Why Optical Networks? DWDM optoelectricl metro networkTrend:寬帶無線網(wǎng)飛速增長寬帶無線網(wǎng)飛速增長Trend:寬帶無線網(wǎng)寬帶無線網(wǎng)(Wi-Fi)飛速增長飛速增長Trend: Wireless / Mobile Integration of 3G and WLAN- offer possibility of achieving anywhere, anytime, hig

30、h speed and low expense Internet accessFuture Internet Research and ExperimentationTodays Internet Internet2 ProjectInternet2 Focus AreasAbilene Connections : Apr-2000Abilene Connections: July 2006Abilene Connections : Apr-2000Abilene International Peering 2006Research andDevelopmentCommercializatio

31、nPartnershipsPrivatizationInternet Development SpiralTodays InternetInternet2 Packet-Switching vs. Circuit-SwitchingnMost important advantage of packet-switching over circuit switching: ability to exploit statistical multiplexing:uEfficient bandwidth usage; ratio between peek and average rate is 3:1

32、 for audio, and 15:1 for data trafficnHowever, packet-switching needs to deal with congestion:uMore complex routersuHarder to provide good network services (e.g., delay and bandwidth guarantees)nIn practice they are combined:uIP over SONET, IP over Frame RelayVirtual-Circuit Packet SwitchingnHybrid

33、of circuit switching and packet switchinguData is transmitted as packetsuAll packets from one packet stream are sent along a pre-established path ( = virtual circuit)nGuarantees in-sequence delivery of packetsnHowever: Packets from different virtual circuits may be interleavednExample: ATM networksuMPLS?Virtual-Circuit Packet SwitchingHost AHost BHost EHost DHost