計算機網(wǎng)絡課程

1、第一章 計算機網(wǎng)絡概述,What is a Network?Types of Networks?Network ArchitectureNetwork ProtocolNetwork history,2014年0818111924596互聯(lián)網(wǎng)訪問量可視化圖 中國是黃色 美國是藍色 日本是紫色 歐洲是紅色,通過ping IP 地址 展示的全球計算機網(wǎng)絡狀況圖。 顏色由 墨綠到紅 逐漸增強,2015年全球總人口7

2、2.7億，互聯(lián)網(wǎng)用戶已有32億人。,2012年騰訊智慧走訪了中國 9 個城市，通過與網(wǎng)民深度交流和對話，收集了 3133 份有效樣本，分析了中國不同城市網(wǎng)民在使用互聯(lián)網(wǎng)方面的多樣性和差異。,中國城市網(wǎng)絡價值圖,1. What is a Network(1),End system point of viewShare Services: E-mail VOD FTP WWW Business,,,,,,,

3、Host,Host,,,,,,,,,,,Host,,Host,,Host,,Host,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1. What is a Network(2),Infrastructure Centric ViewLinks: fiber, copper, satellite, …Equipments: hubs, switches, routers…Applications: FTP, WEB,

4、 X windows, ...,1. What is a Network(3),Definition1（從功能角度）計算機網(wǎng)絡是以共享資源（硬件、軟件和數(shù)據(jù)等）為目的而連接起來的、在協(xié)議控制下，由終端設備、數(shù)據(jù)傳輸設備等組成的系統(tǒng)之集合。Share Resources：Various Devices、AppsProtocol：Soul of Network,？,溝通 交流 協(xié)作,1. What is a Network(3),

5、,,1.計算機網(wǎng)絡定義,,1.計算機網(wǎng)絡定義,2.Types of Networks(1),Geographical distanceLocal Area Networks (LAN): Ethernet, Token ring, FDDIMetropolitan Area Networks (MAN): DQDB, SMDSWide Area Networks (WAN): X.25, ATM, frame relay,2.Ty

6、pes of Networks(2),Information typeData networks vs. Telecommunication networksIPTV VoIP —Converged NetworkApplication(server) typeSpecial purpose networks:military network, fiancial network, credit card network, te

7、lephony general purpose network: internetRight to useprivate: enterprise networkspublic: telephony network, Internet,2.Types of Networks(3),Transport modeWired vs. wirelessFunction Resource subnetCommunication su

8、bnet,2.Types of Networks(4),Topology,,,,哪種好？,2.Types of Networks(5),交換方式：電路（circuit） 交換網(wǎng)報文（segment）交換網(wǎng)分組（packet） 交換網(wǎng),3.Network Architecture(1),功能層次和層次協(xié)議的集合網(wǎng)絡及其部件通過協(xié)議應完成的功能不定義功能的實現(xiàn)細節(jié)和各層協(xié)議之間的接口關系功能的分層---> 分層協(xié)

9、議-? 體系結構,3.Network Architecture(2),,,4.Network Protocol(1),協(xié)議 ( Protocol )計算機網(wǎng)絡同等層次中，通信對等雙方進行信息交換時必須遵守的規(guī)則協(xié)議的組成：語法（syntax)：以二進制形式表示的命令和相應的結構語義（semantics)：命令請求、完成的動作和回送的響應的具體含義定時關系（timing)：有關事件順序的說明,4.Network Protocol

10、（2）,network protocols:machines rather than humansall communication activity in Internet governed by protocols,protocols define format, order of msgs sent and received among network entities, and actions taken on msg tr

11、ansmission, receipt,,human protocols:“what’s the time?”“I have a question”introductions… specific msgs sent… specific actions taken when msgs received, or other events,4.Network Protocol（3）,a human protocol and a c

12、omputer network protocol:,,Excuse me!,,Yes?,,,TCP connection req.,,,,,,5. Network history(1),1961: Kleinrock - queueing theory shows effectiveness of packet-switching1964: Baran - packet-switching in military nets1967

13、 Donald Davies packet switching1967: ARPAnet conceived by Advanced Research Projects Agency1969: first four ARPAnet nodes operational,1972: ARPAnet demonstrated publiclyNCP (Network Control Protocol) first host-ho

14、st protocol first e-mail program,(1)1961-1972: Early packet-switching principles,It happened that the work at MIT (1961-1967), at RAND (1962-1965), and at NPL (1964-1967) had all proceeded in parallel without any of the

15、 researchers knowing about the other work.,Father of ARPAnet, Lawrence G. Roberts, came to DARPA to lead the ARPAnet program in 1966.,5. Network history(2),1972-1980: Internetworking, new and proprietary nets,1970: ALOHA

16、net satellite network in Hawaii1973: Metcalfe’s PhD thesis proposes Ethernet1974: Cerf and Kahn - architecture for interconnecting networkslate70’s: proprietary （專用）architectures: DECnet, SNA, XNAlate 70’s: switching

17、 fixed length packets (ATM precursor)1979: ARPAnet has 200 nodes,Cerf and Kahn’s internetworking principles:minimalism, autonomy - no internal changes required to interconnect networksbest effort service modelstatele

18、ss routersdecentralized controldefine today’s Internet architecture,5. Network history(3),1982: Smtp e-mail protocol defined 1983: Deployment of TCP/IP for NCP1983: DNS defined for name-to-IP-address translation1985

19、: ftp protocol defined,1980-1990: new protocols, a proliferation of networks,5. Network history(4),1990’s: commercialization, the WWW,Early 1990’s: ARPAnet decomissioned1991: NSF lifts restrictions on commercial use of

20、NSFnet (decommissioned, 1995)early 1990s: WWWhypertext HTML, http: Berners-Lee1994: Mosaic, later Netscapelate 1990’s: commercialization of the WWW,Late 1990’s:50 million computers on Internet100 million usersbac

21、kbone links running at 1 Gbps,5. Network history(5),中國互聯(lián)網(wǎng)發(fā)展（1）1987年9月，中國第一封電子郵件 Across the Great Wall we can reach every corner in the world. 揭開了中國人使用互聯(lián)網(wǎng)的序幕1988年初，中國第一個X.25分組交換網(wǎng)建成1990年11月28日，中國正式在SRI-NIC注冊登記了中國的頂級域名C

22、N，從此中國的網(wǎng)絡有了自己的身份標識,5. Network history(6),中國互聯(lián)網(wǎng)發(fā)展（2）1994年4月，通過美國Sprint公司連入因特網(wǎng)的64K國際專線開通，實現(xiàn)了與因特網(wǎng)的全功能連接，中國成為開通因特網(wǎng)的國家1994年9月，電信啟動中國公用計算機互聯(lián)網(wǎng)（CHINANET）1994年10月，啟動中國教育和科研計算機網(wǎng)（CERNET）1997年，電信網(wǎng)（CHINANET）、科技網(wǎng)（CSTNET）、教育網(wǎng)（CERNE

23、T）、金橋網(wǎng)（CHINAGBN）互連互通,5. Network history(7),中國互聯(lián)網(wǎng)發(fā)展:高速網(wǎng)絡國家“九五”、“十五” 科技攻關項目國家 863 高技術研究發(fā)展計劃國家 “十五”863高技術研究發(fā)展計劃中國高速互連網(wǎng)絡示范工程 CAINET中國高速計算機互連試驗網(wǎng)絡 NSFCNETCERNET 2000 （高速網(wǎng)絡）工程面向 21世紀中國教育振興計劃：現(xiàn)代遠程教育工程,5. Network history(8

24、),中國互聯(lián)網(wǎng)發(fā)展：高速網(wǎng)絡,5. Network history(9),中國教育科研網(wǎng)(Cernet-IPv4),5. Network history(10),中國教育科研網(wǎng)——IPv4,5. Network history(11),中國教育科研網(wǎng)——CNGI(IPv6),5. Network history(12),東南大學千兆網(wǎng)絡拓撲結構,5. Network history(13),,5. Network history(14)

25、（人口統(tǒng)計）,5. Network history(15)（學歷結構）,5. Network history(16)（職業(yè)結構）,5. Network history(17),5. Network history(18),5. Network history(19)（總出口帶寬）,5. Network history(20)（主要帶寬分配）,5. Network history(21)（總網(wǎng)頁數(shù)）,5. Network history(