計(jì)算機(jī)網(wǎng)絡(luò)課程-課件

1、第一章 計(jì)算機(jī)網(wǎng)絡(luò)概述What is a Network?Types of Networks?Network ArchitectureNetwork ProtocolNetwork history2014年0818111924596互聯(lián)網(wǎng)訪問(wèn)量可視化圖 中國(guó)是黃色 美國(guó)是藍(lán)色 日本是紫色 歐洲是紅色通過(guò)ping IP 地址 展示的全球計(jì)算機(jī)網(wǎng)絡(luò)狀況圖。 顏色由 墨綠到紅 逐漸增強(qiáng)2015年全球總?cè)丝?2.7億，互聯(lián)網(wǎng)用戶(hù)已有32億人。2012年騰訊智慧走訪了中國(guó) 9 個(gè)城市，通過(guò)與網(wǎng)民深度交流和對(duì)話(huà)，收集了 3133 份有效樣本，分析了中國(guó)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(guó)城市網(wǎng)

2、絡(luò)價(jià)值圖1. What is a Network(1)End system point of viewShare Services: E-mail VOD FTP WWW BusinessHostHostHostHostHostHost1. What is a Network(2)Infrastructure Centric ViewLinks: fiber, copper, satellite, Equipments: hubs, switches, routersApplications: FTP, WEB, X windows, .BackboneSwitchClosetSwitchCl

3、osetSwitchRouterRouterClosetSwitch1. What is a Network(3)Definition1（從功能角度）計(jì)算機(jī)網(wǎng)絡(luò)是以共享資源（硬件、軟件和數(shù)據(jù)等）為目的而連接起來(lái)的、在協(xié)議控制下，由終端設(shè)備、數(shù)據(jù)傳輸設(shè)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)Definition2（從計(jì)算機(jī)網(wǎng)絡(luò)體系角度）計(jì)算機(jī)網(wǎng)絡(luò)是指通過(guò)通信媒介連接起來(lái)、能夠相互通信的自主計(jì)算機(jī)集合。它包括三個(gè)方面的含義：(1) 互

4、連性。計(jì)算機(jī)之間的互連和通信必須借助于物理媒介才可以實(shí)現(xiàn)，但媒介可以有不同的種類(lèi)，如有線介質(zhì)、無(wú)線介質(zhì)等；(2) 自主性。網(wǎng)絡(luò)中的計(jì)算機(jī)之間在地理分布、功能及其實(shí)現(xiàn)、操作系統(tǒng)等方面具有獨(dú)立性，計(jì)算機(jī)接入網(wǎng)絡(luò)不受地點(diǎn)、功能及系統(tǒng)平臺(tái)的限制；(3) 規(guī)范性。計(jì)算機(jī)之間的通信必須具有相同的“語(yǔ)言”才能夠相互理解、交互和協(xié)作，這種“語(yǔ)言”就是網(wǎng)絡(luò)中的“協(xié)議”，網(wǎng)絡(luò)協(xié)議是網(wǎng)絡(luò)工作的基礎(chǔ)。1.計(jì)算機(jī)網(wǎng)絡(luò)定義1.計(jì)算機(jī)網(wǎng)絡(luò)定義2.Types of Networks(1)Geographical distanceLocal Area Networks (LAN): Ethernet, Token ring,

5、FDDIMetropolitan Area Networks (MAN): DQDB, SMDSWide Area Networks (WAN): X.25, ATM, frame relay2.Types of Networks(2)Information typeData networks vs. Telecommunication networksIPTV VoIP Converged NetworkApplication(server) typeSpecial purpose networks:military network, fiancial network, credit car

6、d network, telephony general purpose network: internetRight to useprivate: enterprise networkspublic: telephony network, Internet2.Types of Networks(3)Transport modeWired vs. wirelessFunction Resource subnetCommunication subnet2.Types of Networks(4)Topology 哪種好？2.Types of Networks(5)交換方式：電路（circuit）

7、 交換網(wǎng)報(bào)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(luò)及其部件通過(guò)協(xié)議應(yīng)完成的功能不定義功能的實(shí)現(xiàn)細(xì)節(jié)和各層協(xié)議之間的接口關(guān)系功能的分層- 分層協(xié)議- 體系結(jié)構(gòu)3.Network Architecture(2)4.Network Protocol(1)協(xié)議 ( Protocol )計(jì)算機(jī)網(wǎng)絡(luò)同等層次中，通信對(duì)等雙方進(jìn)行信息交換時(shí)必須遵守的規(guī)則協(xié)議的組成：語(yǔ)法（syntax)：以二進(jìn)制形式表示的命令和相應(yīng)的結(jié)構(gòu)語(yǔ)義（semantics)：命令請(qǐng)求、完成的動(dòng)作和回送的響應(yīng)的具體含義定時(shí)關(guān)系（timing)：有關(guān)

8、事件順序的說(shuō)明4.Network Protocol（2）network protocols:machines rather than humansall communication activity in Internet governed by protocolsprotocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt human protocols:“whats the time?”“I hav

9、e a question”introductions specific msgs sent specific actions taken when msgs received, or other events4.Network Protocol（3）a human protocol and a computer network protocol:Excuse me!Yes?Got thetime?2:00TCP connection req.TCP connectionreply.Get /index.htmtime5. Network history(1)1961: Kleinrock -

10、queueing theory shows effectiveness of packet-switching1964: Baran - packet-switching in military nets1967 Donald Davies packet switching1967: ARPAnet conceived by Advanced Research Projects Agency1969: first four ARPAnet nodes operational 1972: ARPAnet demonstrated publiclyNCP (Network Control Prot

11、ocol) first host-host protocol first e-mail program(1)1961-1972: Early packet-switching principlesIt 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 researchers knowing about the other work. Father of ARPAnet, La

12、wrence G. Roberts, came to DARPA to lead the ARPAnet program in 1966.5. Network history(2)1972-1980: Internetworking, new and proprietary nets1970: ALOHAnet satellite network in Hawaii1973: Metcalfes PhD thesis proposes Ethernet1974: Cerf and Kahn - architecture for interconnecting networkslate70s:

13、proprietary （專(zhuān)用）architectures: DECnet, SNA, XNAlate 70s: switching fixed length packets (ATM precursor)1979: ARPAnet has 200 nodesCerf and Kahns internetworking principles:minimalism, autonomy - no internal changes required to interconnect networksbest effort service modelstateless routersdecentrali

14、zed controldefine todays Internet architecture5. Network history(3)1982: Smtp e-mail protocol defined 1983: Deployment of TCP/IP for NCP1983: DNS defined for name-to-IP-address translation1985: ftp protocol defined1980-1990: new protocols, a proliferation of networks5. Network history(4)1990s: comme

15、rcialization, the WWWEarly 1990s: ARPAnet decomissioned1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)early 1990s: WWWhypertext HTML, http: Berners-Lee1994: Mosaic, later Netscapelate 1990s: commercialization of the WWWLate 1990s:50 million computers on Internet100 mi

16、llion usersbackbone links running at 1 Gbps5. Network history(5)中國(guó)互聯(lián)網(wǎng)發(fā)展（1）1987年9月，中國(guó)第一封電子郵件 Across the Great Wall we can reach every corner in the world. 揭開(kāi)了中國(guó)人使用互聯(lián)網(wǎng)的序幕1988年初，中國(guó)第一個(gè)X.25分組交換網(wǎng)建成1990年11月28日，中國(guó)正式在SRI-NIC注冊(cè)登記了中國(guó)的頂級(jí)域名CN，從此中國(guó)的網(wǎng)絡(luò)有了自己的身份標(biāo)識(shí)5. Network history(6)中國(guó)互聯(lián)網(wǎng)發(fā)展（2）1994年4月，通過(guò)美國(guó)Sprint公司連入因

17、特網(wǎng)的64K國(guó)際專(zhuān)線開(kāi)通，實(shí)現(xiàn)了與因特網(wǎng)的全功能連接，中國(guó)成為開(kāi)通因特網(wǎng)的國(guó)家1994年9月，電信啟動(dòng)中國(guó)公用計(jì)算機(jī)互聯(lián)網(wǎng)（CHINANET）1994年10月，啟動(dòng)中國(guó)教育和科研計(jì)算機(jī)網(wǎng)（CERNET）1997年，電信網(wǎng)（CHINANET）、科技網(wǎng)（CSTNET）、教育網(wǎng)（CERNET）、金橋網(wǎng)（CHINAGBN）互連互通5. Network history(7)中國(guó)互聯(lián)網(wǎng)發(fā)展:高速網(wǎng)絡(luò)國(guó)家“九五”、“十五” 科技攻關(guān)項(xiàng)目國(guó)家 863 高技術(shù)研究發(fā)展計(jì)劃國(guó)家 “十五”863高技術(shù)研究發(fā)展計(jì)劃中國(guó)高速互連網(wǎng)絡(luò)示范工程 CAINET中國(guó)高速計(jì)算機(jī)互連試驗(yàn)網(wǎng)絡(luò) NSFCNETCERNET 2000 （高速網(wǎng)絡(luò)）工程面向 21世紀(jì)中國(guó)教育振興計(jì)劃：現(xiàn)代遠(yuǎn)程教育工程5. Network history(8)中國(guó)互聯(lián)網(wǎng)發(fā)展：高速網(wǎng)絡(luò)5. Network history(9)中國(guó)教育科研網(wǎng)(Cernet-IPv4)5. Network history(10)中國(guó)教育科研網(wǎng)IPv45. Network history(11)中國(guó)教育科研網(wǎng)CNGI(IPv6)5. Network history(12)東南大學(xué)千兆網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu)5. Network history(13)5. Network history(14)（人口統(tǒng)計(jì)）5. N