Computer Science Overview Chap4-Networking and the Internet (1)

1. Computer Science OverviewChap4-Networking and the Internet (1) JainShing Wu

2. Networking and Internet • Connect the computers with communication devices and links • Allow sharing of resources and information

3. History • Communication between calculation machines and early computers • Performed by human users by carrying instructions between them • Internet were demonstrably present in the 19th century • In earlier networks using visual signals

4. History • In 1940, George Stibitz used a Teletype machine to send instructions for a problem set • From his Model at Dartmouth College • To his Complex Number Calculator in New York • received results back by the same time

5. History • Early networks of communicating computers started in the late 1950s • Military radar system Semi-Automatic Ground Environment (SAGE)

6. History • In 1960, semi-automatic business research environment (SABRE) on line • Commercial airline reservation system • American Airlines • Two connected IBM 7090 mainframes • Handling 83,000 calls per day

7. History • Advanced Research Projects Agency (ARPA) • Support by US Department of Defense • Linking output systems like teletypewriters to computers • In 1962, developed by J.C.R. Licklider • "Intergalactic Computer Network“ • A precursor to the ARPANET

8. History • In 1962, The famous Bell 103A dataset standard was also introduced by AT&T • Provided full-duplex service at 300 bit/s over normal phone line

9. History • In 1964, Dartmouth Time Sharing System was developed by researchers at Dartmouth • Distributed users of large computer systems • Massachusetts Institute of Technology used a computer to route and manage telephone connections at the same year

10. History • In 1965, Thomas Marill and Lawrence G. Roberts created the first wide area network (WAN) • This was an immediate precursor to the ARPANET, of which Roberts became program manager • Western Electric in 1965 introduced the first widely used telephone switch that used true computer control

11. History • In 1969, ARPANET network • Connected • University of California at Los Angeles, • Stanford Research Institute, University of California at Santa Barbara • University of Utah • 50 kbit/s circuits

12. History • In 1972, commercial services using X.25 were deployed • Later used as an underlying infrastructure for expanding TCP/IP networks

13. History • Packet switched networks • Mark I at NPL in the UK • ARPANET • CYCLADES • Merit Network • Tymnet • Telenet • Developed in the late 1960s and early 1970s using a variety of protocols

14. History • Notable exceptions were the Norwegian Seismic Array (NORSAR) in 1972 • Followed in 1973 by Sweden with satellite links to the Tanum Earth Station and Peter T. Kirstein's research group in the UK

15. History • In December 1974 • RFC 675 – Specification of Internet Transmission Control Program • Vinton Cerf, YogenDalal, and Carl Sunshine, used the term internet, as a shorthand for internetworking

16. History • ARPANET expanded in 1981 when the National Science Foundation (NSF) developed the Computer Science Network (CSNET) • In 1982, the Internet Protocol Suite (TCP/IP) standardized • Concept of a world-wide network of fully interconnected TCP/IP networks called the Internet was introduced

17. History • TCP/IP network access expanded again in 1986 • NSFNET provided access to supercomputer sites in the United States from research and education organizations • 56 kbit/s (1986) • 1.5 Mbit/s (1987) T1 • 45 Mbit/s (1991) T3

18. History • Commercial internet service providers (ISPs) began to emerge in the late 1980s and early 1990s

19. History • Usenet • Established by Duke University graduate students Tom Truscott and Jim Ellis in 1980 • Usenet resembles a bulletin board system (BBS)

20. History • Robert Cailliau published "Hypertext project" called "WorldWideWeb" • (one word, also "W3") • (on 12 November 1990) • “Web" of "hypertext documents" to be viewed by "browsers" using a client–server architecture

21. History • A NeXT Computer in 1990 • Used by Berners-Lee • The world's first web server • The first web browser on it

22. History • The original Gopher system released in late spring of 1991 • Mark McCahill, FarhadAnklesaria, Paul Lindner, Daniel Torrey, and Bob Alberti • University of Minnesota

23. History • The advantage of Gopher • A file-like hierarchical arrangement that would be familiar to users • Including WAIS, the Archie and Veronica search engines, FTP, and Usenet • A simple syntax • A system that can be created quickly and inexpensively • Extending the file system metaphor, such as searches

24. History • In February 1993, the University of Minnesota announced that Gopher would charge licensing fees for the use of its implementation of the Gopher server

25. History • Bulletin Board System (BBS) • Software that allows users to connect and log in to the system using a terminal program • Popular at the late 1970s • Using modems to connect a server • Particularly slow and file transfers were typically limited to text files • In the early 1990s, some BBSesallowed access via a Telnet (packet switched network or packet radio) connection

26. Networking and Internet • Classified according to a wide variety of characteristics • Medium used • Communications protocol • Scale • Topology • Benefit • Organizational scope

27. Network Scale • Local area network (LAN) • Wide area network (WAN)

28. Local Area Network • Computer network • Interconnects computers in a limited area • Home • School • Computer laboratory • Office building

29. Wide area network • Network that covers a broad area • Internet can be considered a WAN • Businesses • Governments • Organizations • Individuals for almost any purpose imaginable

30. Network Medium • Wired • Twisted pair • Coaxial cable • Optical fiber • Wireless • GSM • 3G • Beyond 3G • Bluetooth • WiFi

31. Twisted Pair • The most widely used medium for telecommunication • Ordinary telephone wires consist of two insulated copper wires twisted into pairs

32. Twisted Pair

33. Twisted Pair • Advantage • Thin, flexible cable that is easy to string between walls • More lines can be run through the same wiring ducts • UTP costs less than any other type of LAN cable • Electrical noise going into or coming from the cable can be prevented.[7] • Cross-talk is minimized.[7]

34. Twisted Pair • Disadvantage • Susceptibility to electromagnetic interference greatly depends on the pair twisting schemes • Introduce signaling delays in video applications that send information across multiple parallel signal wires

35. Coaxial Cable • Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880

36. Coaxial Cable

37. Coaxial Cable • Advantage • Physical size • Frequency performance • Attenuation (訊號衰減) • Power handling capabilities • Flexibility • Strength • Cost

38. Coaxial Cable • Disadvantage • Insulation may degrade • A single thread of the braid or filament of foil touches the center conductor => the signal will be shorted causing significant or total signal loss • Connector or splice must be properly attached to the shield, as this provides the path to ground for the interfering signal

39. Optical Fiber • Aflexible, transparent fiber made of glass (silica) or plastic to transmit light between the two ends of the fiber • Used in fiber-optic communications • Permits transmission over • longer distances • higher bandwidths (data rates) than other forms of communication

40. Optical Fiber

41. Optical Fiber • Advantage • A single fiber can carry much more data than electrical cables runs at 100 Mbit/s or 1 Gbit/s speeds • Fiber is also immune to electrical interference • Good for protecting communications equipment in high voltage environments

42. Global System for Mobile Communications (GSM) • Developed by the European Telecommunications Standards Institute (ETSI) • Describe protocols for second generation (2G) digital cellular networks • Replacement for first generation (1G) analog cellular networks

43. Global System for Mobile Communications (GSM) • Expanded over time to include data communications • First by circuit switched transport • Packet data transport via GPRS (General Packet Radio Services) • EDGE (Enhanced Data rates for GSM Evolution or EGPRS)

44. Global System for Mobile Communications (GSM)

45. 3G-3rd Generation of Mobile Telecommunications Technology • Mobile devices and mobile telecommunication services and networks • International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union

46. 3G-3rd Generation of Mobile Telecommunications Technology • Types • UMTS (Universal Mobile Telecommunications System) • WCDMA • TD-SCDMA (China) • Popular in Europe, Japan • CDMA2000 • Popular in North America, South Korea

47. 3G-3rd Generation of Mobile Telecommunications Technology • UTMS

48. Beyond 3G • In telecommunications, 4G is the fourth generation of mobile phone mobile communications standards • A successor of the third generation (3G) standards

49. Beyond 3G • Types • LTE • Frist in Scandinavia since 2009 • WiMax • First in South Korea in 2006

50. WiMax • IEEE 802.16 Standard • Wireless communications standard designed • Provide 30 to 40 Mbits/s data rates • Providing up to 1 Gbit/s for fixed stations (2011 update) • 大同電信