计算机网络 Internet 历史 现状与未来PPT课件

1、计算机网络（Internet）历史，现状与未来,计算机网络,Transportation service: move objects horse, train, truck, airplane . Communication network: move information bird, fire, telegraph, telephone, 计算机网络Internet ,Communication networks can be classified based on the way in which the nodes exchange information:,A Taxonomy of

2、 Communication Networks,Communication Network,SwitchedCommunication Network,BroadcastCommunication Network 广播，电视,Circuit-SwitchedCommunication Network 电话,Packet-SwitchedCommunication Network,Datagram Network,Virtual Circuit Network,Internet,The example,通话在 C 到 D (只经过一个本地交换机) 的连接上进行 通话在 A 到 B (经过四个交换

3、机) 的连接上进行 思考：电话交换对于计算机是否适合？ 效率/成本 应用实时,(,(,(,(,交换机,交换机,交换机,交换机,用户线,用户线,中继线,中继线,B,D,C,A,Circuit Switching （电路交换-电话）,A node (switch) in a circuit switching network,Circuit Switching: Multiplexing/Demultiplexing,Time divided in frames and frames divided in slots Relative slot position inside a frame de

4、termines which conversation the data belongs to Needs synchronization between sender and receiver In case of non-permanent conversations Needs to dynamic bind a slot to a conservation How to do this?,Timing in Circuit Switching,propagation delay between Host 1 and Node 1,propagation delay between Ho

5、st 2 and Node 1,报文,在发送端，先把较长的报文划分成较短的、固定长度的数据段。,Packet Switching （分组/包交换） 1961,Computer networks self-development-packet switching,分组交换网以“分组”(也称 包)作为数据传输单元 依次把各分组发送到接收端（假定接收端在左边）。,Computer networks development-packet switching,最后，在接收端把收到的数据恢复成为原来的报文。 这里我们假定分组在传输过程中没有出现差错，在转发时也没有被丢弃。,数 据,数 据,数 据,Pack

6、et Switching （分组/包交换） 1961,Data are sent as formatted bit-sequences, so-called packets Packets have the following structure: Header and Trailer carry control information (e.g., destination address, check sum) Each packet is passed through the network from node to node along some path (Routing) At ea

7、ch node the entire packet is received, stored briefly, and then forwarded to the next node (Store-and-Forward Networks) Typically no capacity is allocated for packets,Router A,Router B,Router C,Router D,Router E,Packet Switching - Example,Router F,Timing of Datagram Packet Switching,Packet 3,Packet

8、3,Packet 1,Packet 2,Packet 1,Packet 2,Packet 1,Packet 2,Packet 3,processing delay of Packet 1 at Node 2,Host 1,Host 2,Node 1,Node 2,propagation delay between Host 1 and Node 2,transmission time of Packet 1 at Host 1,Packet Switching （分组/包交换） 1961,A node in a packet switching network,Packet Switching

9、: Multiplexing/Demultiplexing,Data from any conversation can be transmitted at any given time How to tell them apart? Use meta-data (header) to describe data Datagram Packet Switching Each packet is independently switched Each packet header contains destination address No resources are pre-allocated

10、 (reserved) in advance Example: IP networks,Use Queuing models to Describe the behavior of queuing systems Evaluate system performance,Model: Queuing System,Queuing System,Queue,Server,Customers,Response Time vs. Arrivals,Internet 历史(1) Sep69 1st IMP in UCLA, Oct69 2nd IMP in SRI Internet 之父- L. Kle

11、inrock1999 1969,History of the Internet (2),History of the Internet (3),Sep69 1st IMP in UCLA Oct69 2nd IMP in SRI 22:30 29Oct69 LOGIN from UCLA to SRI CLA We sent an “L” - did you get the “L”? YEP! We sent a “O” - did you get the “O”? YEP! We sent an “G” - did you get the “G”? Crash!,历史的网络（4）,1961-

12、1972：早期的分组交换原理 1961:让排队理论表明，分组交换的有效性 1964: Baran -军事网分组交换 1967:阿帕网由高级研究计划局（Licklider，罗伯茨）1969:第一网络节点的操作 1972:网络有15个节点阿帕网公开展示NCP （网络控制协议）第一主机协议第一封电子邮件程序,History of the Internet (5),1972-1980: Internetworking, research networks 1970:ALOHAnet satellite network in Hawaii (Abramson) 1973:Metcalfes PhD th

13、esis proposes Ethernet 1974:Cerf and Kahn - 2004 A.M. Turing Award -define todays Internet architecture minimalism, autonomy no internal changes required to interconnect networks best effort service model stateless routers decentralized control 1979:ARPAnet has 200 nodes, 56 kbps Late 70s: proprieta

14、ry architectures: DECnet, SNA Late 70s: switching fixed length packets (- ATM),History of the Internet (6),1980s new protocols, a proliferation of net 1983:deployment of TCP/IP. (Critical separation; Cohen) 1982:SMTP e-mail protocol defined 1983:DNS defined for name-to-IP-address translation mid-198

15、0s: IETF active 1985:FTP protocol defined 1988:TCP congestion control new national networks: Csnet, BITnet, Minitel , NSFnet (1.5 Mbps,10,000 computers), NSI (NASA), ESNet(DOE), DARTnet, TWBNet (DARPA), 100,000 hosts connected to confederation of networks,History of the Internet (7),1990s: commercia

16、lization, the WWW Early 1990s: ARPAnet decommissioned 1991: NSFnet (45 Mbps) - commercial use of NSF (decommissioned, 1995) Late 1990s: multiple private backbones 50 million computers on Internet 100 million+ users backbone links running at 1 Gbps Early 1990s: WWW hypertext Bush 1945, Nelson 1960s H

17、TML, http: Berners-Lee 1994: Mosaic, later Netscape late 1990s: commercialization of the WWW,Internet 提供的服务,Shared access to computing resources telnet (1970s) Shared access to data / files FTP, NFS, AFS (1980s) Communication medium over which people interact email (1980s), on-line chat / messaging

18、(1990s) audio, video (1990s) replacing telephone network? A medium for information dissemination USENET (1980s) WWW (1990s) replacing newspaper, magazine? audio, video (1990s) replacing radio, CD, TV?,Internet Physical Infrastructure,Classification by Coverage,模型, 协议, 分层,Protocol Architecture,Dont N

19、eed All Layers Everywhere,Protocol Data Unit - PDUs,Network Components (Examples),Fibers,Coaxial Cable,Links,Interfaces,Switches/routers,Ethernet card,Wireless card,Large router,Telephone switch,Growth of the Internet,Today: backbones run at 2.4/10/100 Gbps, 500 millions computers in 150 countries,中

20、科院高能物理所 1993年3月64Kbps 1986.8.25 Email TJU:1995年3月22日 2009年7月 网民 3.4亿 WWW站 306万 CN域名 1296万 国际出口带宽 748 Gbps 连接美国、俄罗斯、法国、英国、德国、日本、韩国、新加坡等 宽带接入速度远远落后于发达国家,Internet 在中国,趋势: 网络时代,每一件事务都是数字的: 声音, 视频, 音乐, 画片 每一件事务都是在线的: 银行, 医疗, 航空, 天气情况, 公路交通, 每个人之间都是相互联系的:医生,教师,经济人,母亲,儿子, 朋友, 敌人 实现家庭 教育， 办公， 购物， 娱乐/网上娱乐 虚拟

21、工作场所 2000年，美国有五千五百万人实现远程工作 网络制造/电子商务,趋势: 网络时代,计算机集成制造系统/先进制造/信息化CIMS (Computer Integrated Manufacturing),1973 Dr. Joseph Harrington 目标：市场竞争 - T, Q, C, S 时间T（即开发新产品的时间或成熟产品的上市时间）、质量Q、成本C和服务S 核心思想 系统的观点 - 全局优化 企业的各个环节，包括市场分析、产品设计、加工制造、经营管理及售后服务的全部经营活动，是不可以分割的整体. 信息的观点 - 信息集成 企业的运行是信息采集，传递，加工处理的过程. 产品可

22、以看作数据的物质表现.,目标-提高竞争力（CIMS-Internet）,70年代前,降低劳动成本,降低产品成本,70年代,提高企业整体效益,降低产品成本,提出CIMS,80年代,TQCS,CIMS推广应用,90年代,新产品开发，信息、知识,CIMS发展,2000年代,核心：服务/用户,范围：全球企业间/供应链,资源：信息、知识（无时空）,网络制造/ 电子商务,网络制造,Internet从单纯的信息工具变成”E时代”的关键资源.全球经济一体化成为制造业变革的最根本的推动力 基于Internet的虚拟制造与虚拟装配 在相互联结的网络上，建立24小时工作的协同工作组，大大加快了设计进度、及时获得所需

23、要的零部件，减少库存、降低成本，提高质量 网络制造的本质特性就是产品的制造过程更加分散化，信息的传递网络化，信息的流动伴随着各项工作的并发进行而同时发生,电子商务,信息技术和Internet引发的商务过程的变化 利用以Internet为核心的信息技术，进行商务活动和企业资源管理 CIMS是企业实施电子商务的基础 企业实施电子商务是CIMS发展的主要标志和主要内容,竞争环境改变,核心 产品竞争,电子商务产生背景,服务竞争,范围 单个企业,全球多企业,资源 人、财、物,信息、知识,管理重心迁移,生产管理,供应/营销链管理,集中内部资源,整合外部资源,离散管理,集约管理,商务模式转化,文秘型管理 关

24、注后台（企业内部） 关注业务记录（报表） 地区性 推销产品为中心 （卖方市场）,自我服务型管理 关注前端（客户关系） 要求商业智能（分析） 全球化 客户为中心 （买方市场）,传统商务,电子商务,客户,供应商,合作伙伴,网络智能,市场营销,产品/服务 销售,产品制造,服务/支持,e企业的业务体系结构,协同产品商务( CPC),用户在互联网上参与产品的开发、设计及修订。 在虚拟市场空间中，顾客与生产者及供应商一起参与产品生命周期中的每一项技术及商业环节。 不受地域及时间的限制，信息可以快速地流动。,企业的发展趋势,部门之间的障碍,业务过 程重组 IDS Sheer,业务流程,2000年以后,电子商

25、务工程 IDS Sheer,企业之间的障碍,网络制造-电子商务,网络发展趋势,趋势: 融合 趋势: 泛在（Ubiquitous） 趋势: 信息爆炸 更多的网络业务流量 数据流量 话声流量 更快的传输介质/骨干网（Backbone） 更大的带宽（Bandwidth） 宽带无线网飞速增长(WLAN) (Wi-Fi) Everything over IP,趋势: 融合,新闻/广告-媒体-信息提供者 数字媒体产品 有线电视 视频传输 电话 声音传输 计算机 数字媒体存储/处理 信息提供者和信息传输者的结合 电话公司, 有线公司, 娱乐事业, 和计算机公司的结合,Trend:,趋势: 更快的传输介质,局

26、域网：1 Gbps over 4-pair UTP-5 up to 100 m, 10Gbps being discussed Was 1 Mbps (1Base-5) in 1984 骨干网：光纤DWDM ( Dense Wavelength Division Multiplexing) OC-768 = 40 Gbps over a to 65 km, 1600 Gbps - 10 Tbps Was 100 Mbps (FDDI) in 1993 无线网：54 /500 Mbps(100-2km-50km) wireless networks, 2.5 Gbps to 5km using

27、light Was 1 Mbps (IEEE 802.11) in 1998,Why Optical Networks? DWDM optoelectricl metro network,Trend:宽带无线网飞速增长,Trend:宽带无线网(Wi-Fi)飞速增长,Trend: Wireless / Mobile,Integration of 3G and WLAN- offer possibility of achieving anywhere, anytime, high speed and low expense Internet access,Future Internet Resea

28、rch and Experimentation,Todays Internet,Millions of users Web, email, low-quality audio ratio between peek and average rate is 3:1 for audio, and 15:1 for data traffic However, packet-switching needs to deal with congestion: More complex routers Harder to provide good network services (e.g., delay a

29、nd bandwidth guarantees) In practice they are combined: IP over SONET, IP over Frame Relay,Virtual-Circuit Packet Switching,Hybrid of circuit switching and packet switching Data is transmitted as packets All packets from one packet stream are sent along a pre-established path ( = virtual circuit) Gu

30、arantees in-sequence delivery of packets However: Packets from different virtual circuits may be interleaved Example: ATM networks MPLS?,Virtual-Circuit Packet Switching,Router A,Router B,Router C,Router D,Router E,1. Connection Establishment,2. Information Transfer,3. Circuit Disconnect,Virtual Cir

31、cuit Packet Switching-Example,Router F,Timing of Virtual-Circuit Packet Switching,Host 1,Host 2,Node 1,Node 2,propagation delay between Host 1 and Node 1,VC establishment,VC termination,Data transfer,Asynchronous Transfer Mode: ATM,1990s/00 standard for high-speed (155Mbps to 622 Mbps and higher) Br

32、oadband Integrated Service Digital Network architecture Goal: integrated, end-end transport of carry voice, video, data meeting timing/QoS requirements of voice, video (versus Internet best-effort model) “next generation” telephony: technical roots in telephone world packet-switching (fixed length p

33、ackets, called “cells”) using virtual circuits,ATM reference model,How far along are we?,Standardization bodies - ATM Forum, ITU-T We may never see end-to-end ATM (1997) ATM - too complex - too expansive Backbone: - 1995 vBNS (ATM) - 1998 Abilene (SONET) - 2000 IP over DWDM Internet technology + ATM

34、 philosophy but ATM ideas continue to powerfully influence design of next-generation Internet ex: MPLS, admission ctl., resource reservation, .,Best of Both Worlds,Multiprotocol label switching (MPLS) MPLS + IP form a middle ground that combines the best of IP and the best of virtual circuit switchi

35、ng technologies ATM and Frame Relay cannot easily come to the middle so IP has!,Label Encapsulation,MPLS Encapsulation is specified over various media types. Top labels may use existing format, lower label(s) use a new “shim” label format.,Label Substitution,Have a friend go to B ahead of you using

36、one of the previous two techniques. At every road they reserve a lane just for you. At every intersection they post a big sign that says for a given lane which way to turn and what new lane to take.,We are at an Impasse,ISPs are unlikely candidates for architectural change We cant test new architect

37、ures - Despite sizable investments in testbeds We cant deploy new architectures - And things are getting worse, not better Yet there are pressing requirements for which the current architecture is not well suited,GENI (Global Environment for Network Innovations) - NSF 2005 (1),What is GENI? GENI is

38、a facility concept being explored by the US computing community back to an NSF workshop in 2005 focus on architectural research, and provide the experimental infrastructure needed to support that research focus on the research agenda (and infrastructure needs) of the optical, wireless, sensor network, and distributed systems communities,GENI (Global Environment for Network Innovations) (2),The goal of GENI Goal: a Future Internet that meets the demands of 21st century to increase the quality and quantity of experimental research outcomes in networking and distributed s