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1、计算机网络技术的历史和新进展,主要内容,Internet的发展和成功经验 高速计算机网络技术发展的现状 国际高速计算机网络技术研究计划 中国计算机网络技术研究计划 高速计算机网络技术发展战略 机会和挑战并存，挑战大于机会,What is a Network?(from end system point of view),Network offers a service: move information bird, fire, messenger, truck, telegraph, telephone, Internet another example, transportation ser
2、vice: move objects horse, train, truck, airplane . What distinguish different types of networks? The services they provide What distinguish the services? latency bandwidth loss rate number of end systems service interface (how to invoke?) other details reliability, unicast vs. multicast, real-time,
3、message vs. byte .,What is a Network?Infrastructure Centric View,Electrons and photons as communication medium Links: fiber, copper, satellite, Switches: mechanical/electronic/optical, crossbar/Banyan Protocols: TCP/IP, ATM, MPLS, SONET, Ethernet, PPP, X.25, FrameRelay, AppleTalk, IPX, SNA Functiona
4、lities: routing, error control, congestion control, Quality of Service (QoS) Applications: FTP, WEB, X windows, .,Types of Networks,Geographical distance Local Area Networks (LAN): Ethernet, Token ring, FDDI Metropolitan Area Networks (MAN): DQDB, SMDS Wide Area Networks (WAN): X.25, ATM, frame rela
5、y Information type data networks vs. telecommunication networks Application type special purpose networks: airline reservation network, banking network, credit card network, telephony general purpose network: Internet,Types of Networks,Right to use private: enterprise networks public: telephony netw
6、ork, Internet Ownership of protocols proprietary: SNA open: IP Technologies terrestrial vs. satellite wired vs. wireless Protocols IP, AppleTalk, SNA,The Internet,Global scale, general purpose, heterogeneous-technologies, public, computer network Internet Protocol open standard: Internet Engineering
7、 Task Force (IETF) as standard body technical basis for other types of networks Intranet: enterprise IP network Developed by the research community,History of the Internet,70s: started as a research project, 56 kbps, 100 computers 80-83: ARPANET and MILNET split, 85-86: NSF builds NSFNET as backbone
8、, links 6 Supercomputer centers, 1.5 Mbps, 10,000 computers 87-90: link regional networks, NSI (NASA), ESNet(DOE), Bartnet, 100,000 computers 90-92: NSFNET moves to 45 Mbps, 16 mid-level networks 94: NSF backbone dismantled, multiple private backbones Today: backbones run at 2.4 Gbps, 10s millions c
9、omputers in 150 countries,Growth of the Internet,Number of Hosts on the Internet: Aug. 1981 213 Oct. 1984 1,024 Dec. 1987 28,174 Oct. 1990 313,000 Oct. 1993 2,056,000 Apr. 1995 5,706,000 Jul. 1997 19,540,000 Jul. 2000 93,047,785,Recent Growth (1991-2000),Who is Who on the Internet ?,Internet Enginee
10、ring Task Force (IETF): The IETF is the protocol engineering and development arm of the Internet. Subdivided into many working groups, which specify Request For Comments or RFCs. IRTF (Internet Research Task Force): The Internet Research Task Force is a composed of a number of focused, long-term and
11、 small Research Groups. Internet Architecture Board (IAB): The IAB is responsible for defining the overall architecture of the Internet, providing guidance and broad direction to the IETF. The Internet Engineering Steering Group (IESG): The IESG is responsible for technical management of IETF activi
12、ties and the Internet standards process. Standards. Composed of the Area Directors of the IETF working groups.,Internet Standardization Process,Services Provided by the Internet,Todays Vision,Everything is digital: voice, video, music, pictures, live events Everything is on-line: bank statement, med
13、ical record, books, airline schedule, weather, highway traffic, toaster, refrigerator Everyone is connected: doctor, teacher, broker, mother, son, friends, enemies,What is Next?,Electronic commerce virtual enterprise Internet entertainment interactive sitcom World as a small village community organi
14、zed according to interests enhanced understanding among diverse groups Electronic democracy little people can voice their opinions to the whole world bridge the gap between information haves and have nos Electronic terrorism hacker can bring the whole world to its knee,Industrial Players,Telephone c
15、ompanies own long-haul and access communication links, customers Cable companies own access links Wireless/Satellite companies alternative communication links Utility companies: power, water, railway own right of way to lay down more wires Medium companies own content Internet Service Providers Equi
16、pment companies switches/routers, chips, optics, computers Software companies,Commercial Internet after 1994,NSF Network,Regional ISP,America On Line,IBM,Bartnet,Campus Network,Joes Company,Stanford,Xerox Parc,Berkeley,NSF Network,Internet MCI,UUnet,SprintNet,Modem,IBM,Backbone,ISP,ISP,Internet Physical Infrastructure,Residential Access Modem DSL Cable modem Satellite,Enterprise/ISP access, Backbone transmission T1/T3,
