1、计算机网络（Internet） 历史，现状与未来,舒炎泰 2010,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 T
2、axonomy of Communication Networks,Communication Network,Switched Communication Network,Broadcast Communication Network 广播，电视,Circuit-Switched Communication Network 电话,Packet-Switched Communication Network,Datagram Network,Virtual Circuit Network,Internet,Circuit Switching （电路交换-电话）,A node (switch) i
3、n a circuit switching network,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 (经过四个交换机) 的连接上进行 思考：电话交换对于计算机网络是否适合？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,Timing in Circuit Switching,propagation delay between Host 1 and Node 1,propagation delay between Host 2 and Node 1,Computer
4、 networks self-development - packet switching,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。,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,Rout
5、er A,Router B,Router C,Router D,Router E,Packet Switching - Example,Router F,Timing of Datagram Packet Switching,Packet 3,Packet 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 No
6、de 2,transmission time of Packet 1 at Host 1,Packet Switching （分组/包交换） 1961,A node in a packet switching network,Use Queuing models to Describe the behavior of queuing systemsEvaluate system performance,Model: Queuing System,Queuing System,Queue,Server,Customers,Response Time vs. Arrivals,Internet 历
7、史(1) Sep69 1st IMP in UCLA, Oct69 2nd IMP in SRI Internet 之父- L. Kleinrock 1999 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
8、“O”? YEP! We sent an “G” - did you get the “G”? Crash!,Internet Physical Infrastructure,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, 600 m
9、illions computers in 180 countries,1993年3月 中科院高能物理所 64 Kbps TJU:1995.3.22 2009年12月 网民3.8亿 普及率28.9% WWW站 323万 CN域名 1300万 国际出口带宽 866Gbps连接美国、俄罗斯、法国、英国、德国、日本、韩国、新加坡等,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，
10、 娱乐/网上娱乐 虚拟工作场所 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，
11、加工处理的过程. 产品可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
12、了设计进度、及时获得所需要的零部件，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
13、模式转化,文秘型管理 关注后台（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,
14、2000年以后,电子商务工程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:,Why
15、 Optical Networks? DWDM optoelectricl metro network,Trend:宽带无线网飞速增长,Trend: Wireless / Mobile,Future Internet Research and Experimentation,Todays Internet,Millions of usersWeb, email, low-quality audio & videoInterconnect personal computers and serversApplications adapt to underlying technologyTodays
16、 Internet Doesnt Provide reliable end-to-end performance Encourage cooperation on new capabilities Allow testing of new technologies Support development of revolutionary applications,Internet2 Project,Develop and deploy advanced network applications and technologies, accelerating the creation of tom
17、orrows Internet. Goals Enable new generation of applications Re-create leading edge R&E network capability Transfer capability to the global production Internet 206 University Members, Jan. 2005,Internet2 Focus Areas,Advanced Network Infrastructure - AbileneBackbones operate at 10 Gbps capacity - 10
18、0 Gbps (2007)Middleware A layer of software between the network and the applications Authentication, Identification, Authorization, Directories, SecurityEngineeringIPv6, Measurement, Multicast, QoS, Routing, Security, TopologyAdvanced ApplicationsDistributed computation, Virtual laboratories, Digita
19、l libraries, Distributed learning, Digital video, Tele-immersion, All of the above in combination,Abilene Connections : Apr-2000,Abilene Connections: July 2006,Abilene Connections : Apr-2000,Abilene International Peering 2006,Research and,Development,Commercialization,Partnerships,Privatization,Inte
20、rnet Development Spiral,Todays Internet,Internet2,Packet-Switching vs. Circuit-Switching,Most important advantage of packet-switching over circuit switching: ability to exploit statistical multiplexing: Efficient bandwidth usage; ratio between peek and average rate is 3:1 for audio, and 15:1 for dat
21、a traffic However, packet-switching needs to deal with congestion: More complex routers Harder to provide good network services (e.g., delay and bandwidth guarantees) In practice they are combined: IP over SONET, IP over Frame Relay,Virtual-Circuit Packet Switching,Hybrid of circuit switching and pa
22、cket switching Data is transmitted as packets All packets from one packet stream are sent along a pre-established path ( = virtual circuit) Guarantees in-sequence delivery of packets However: Packets from different virtual circuits may be interleaved Example: ATM networks MPLS?,Virtual-Circuit Packe
23、t Switching,Router A,Router B,Router C,Router D,Router E,1. Connection Establishment,2. Information Transfer,3. Circuit Disconnect,Virtual Circuit 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 e
24、stablishment,VC termination,Data transfer,We are at an Impasse,ISPs are unlikely candidates for architectural changeWe cant test new architectures - Despite sizable investments in testbedsWe cant deploy new architectures - And things are getting worse, not betterYet there are pressing requirements f
25、or which the current architecture is not well suited,The Communitys Response,Focus on areas where we can have impact:Empirical studiesIncremental changes (subject to current constraints)Small stream of architectural proposalsPaper designs without hope of deploymentMore science fiction than engineeri
26、ngHave largely abandoned hope of effecting fundamental architectural changeLiving with, rather than overcoming, the impasse,Overcoming the Impasse?,Must be able to test new architectures:Wide range of architecturesReal traffic from willing individualsLow overhead for individual researchersMeet the g
27、rand challenge of reinventing the InternetEmpirical, incremental research is great, but not enoughIf someone put us in charge, what would we do?What about deployment?Several options, none good, but no excuse to not have an answer to the grand challenge,Testing: Virtual Testbed,Overlay testbed: (thin
28、k RON, etc.)Host proxy directs packets to overlayProxy must architecturally neutral, and flexibleIndividuals (anywhere) opt-in by turning on proxyShared testing infrastructure (think Planetlab)Overlay nodes shared among experimentsSlicing on per-packet timescalesVirtualized routersThese ideas have t
29、urned into the GENI program,GENI (Global Environment for Network Innovations) - NSF 2005 (1),What is GENI? GENI is 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 su
30、pport 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 centuryto increase t
31、he quality and quantity of experimental research outcomes in networking and distributed systemsto accelerate the transition of these outcomes into products and services enhance economic competitiveness and secure the Nations futureUltimately, to lead to a transition of the Internet,FIND (Future Inte
32、rnet Network Design) NSF 2006,FIND asks two broad questions:What are the requirements for the global network in 15 years How would we re-conceive tomorrows global network today, if we could design it from scratch? FIND program solicits “clean slate process“ research proposals in the broad area of ne
33、twork architecture, principles, and design,FIRE (Future Internet Research and Experimentation) European 2007,FIRE is an experimentally-driven long-term research initiative on Future Internet concepts, protocols and architecturesencompassing technological, industrial and socio-economic aspects acting
34、 as proof-of-concept of the newly proposed technologies and services FIRE RESEARCH Long term multidisciplinary research on future internet paradigms Open to fresh bottom-up ideas with no backwards-compatibility constraints Building on the FET SAC initiative “Situated and Autonomic Communications” Considering at the same time technological, economic and social/policy aspects Build in from the outset and on all levels the right balance between security / accountability and privacy,
