1. Introduction to Computer Network1 Introduction to Computer Networks University of Ilam Dr. Mozafar Bag-Mohammadi

2. Introduction to Computer Network 2 Outline Agenda Policy, Grading, reading materials, etc. Communication. Overview and history of the Internet

3. Introduction to Computer Network 3 Agenda To establish a base for future computer network work and study. Review networking technologies, protocols. Finally, prepare to perform some projects in computer networks which are essential in national development, designing and building switches, routers, etc.

4. Introduction to Computer Network 4 Course Materials Course Web page  visit regularly Textbook  مهندسی اینترنت، احسان ملکیان، انتشارات نص  “Computer Networks, A system approach”. Peterson & Davie 3rd edition

5. Introduction to Computer Network 5 Prerequisition General knowledge in Computer. Fluency in English, specially reading. C programming. Knowledge of UNIX (LINUX) system and programming.

6. Introduction to Computer Network 6 Communication as need. Base of community  Collection of trees is not a community. Transferring data, knowledge, experience among people  Base of civilization. Psycological need.  Love, affection.  Just talking.  Releasing someone.  Base of Culture.

7. Introduction to Computer Network 7 Primary Communication means Language  Conventions Body Language,  Meta language.  Universal. Problems:  Limited in Time and space.  We are struggling all the history to overcome these limitation.

8. Introduction to Computer Network 8 Communication elements Producer, Sender  Speaker Consumer, Receiver  Listener They both do processing and have limitation Message- Talk Transfer media, like air  Substance  Capacity  Delay

9. Introduction to Computer Network 9 Type of communication One to one  Direct talk. One to many  Talks, conferencing Many to Many  Like mass media, newspaper. Domain of communication  Small, primary society  Medium, more developed society.  Large, more advance society.

10. Introduction to Computer Network 10 First Step- Writing One of the most important human being invention. (Why?) Overcome the primary limitations.  Time: By writing it down.  Space: Distributing more copies, library, post, etc. Problems:  Indirect Communication, Through paper.  Slow in producing and consuming  Need proficiency  Encoding message

11. Introduction to Computer Network 11 Next Step- Mailing Distribute messages as fast as and as far as possible. Overcome mostly space limitation, while widen the domain of communication. Media- human being network system. Indirect communication. Encoded message Slow.

12. Introduction to Computer Network 12 New wave- Telegraph In 1837, Samuel B. Morse invented it. Text message is encoded by dot and dashed (binary, digital system). Message switching, human coding for efficiency, and hop by hop routing. Fast transmission, (Time limitation) Slow production (25-30 word/min) The daily Telegraph.

13. Introduction to Computer Network 13 Telephone In 1876, While working on multiplexing telegraph, invented By A. Graham Bell. One to one, completely real time communication. No need to proficiency. Fast, (time limitation) Easy to use or produce data. Exponential growths, 1000 in 1877 to 50,000 in 1880

14. Introduction to Computer Network 14 Broadcast media Printing, newspapers,  Easy to reproduce the same data.  Easy to distribute message.  Slow in producing and contribution. Radio  Easy to distribute message.  Fast in producing and contribution of message.  Limited of type of message, only voice. TV  All like radio, but with richer data.

15. Introduction to Computer Network 15 Computer Network Fast in producing, processing, distributing and consuming messages. No limitation in time and space. Support different type of communication.  Mass media, news group.  One to many, mailing list.  One to one, mail, chat, talk. Support of different type of message, data Only problem, need proficiency.

16. Introduction to Computer Network 16 History of the Internet 70’s: started as a research project, 56 kbps, < 100 computers 80-83: ARPANET and MILNET split, 85-86: NSF builds NSFNET as backbone, links 6 Supercomputer centers, 1.5 Mbps, 10,000 computers 87-90: link regional networks, NSI (NASA), ESNet(DOE), DARTnet, TWBNet (DARPA), 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 computers in 150 countries

17. Introduction to Computer Network 17 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. 1999 59,249,900 Jul. 2001 117,288,000 Data available at: http://www.netsizer.com/

18. Introduction to Computer Network 18 Recent Growth (1991-2000)

19. Introduction to Computer Network 19 Services Provided by the Internet Shared access to computing resources  telnet (1970’s) Shared access to data/files  FTP, NFS, AFS (1980’s) Communication medium over which people interact  email (1980’s), on-line chat rooms, instant messaging (1990’s)  audio, video (1990’s) replacing telephone network? A medium for information dissemination  USENET (1980’s)  WWW (1990’s) replacing newspaper, magazine?  audio, video (1990’s) replacing radio, CD, TV?

20. Introduction to Computer Network 20 Today’s Vision Everything is digital: voice, video, music, pictures, live events Everything is on-line: bank statement, medical record, books, airline schedule, weather, highway traffic, toaster, refrigerator … Everyone is connected: doctor, teacher, broker, mother, son, friends, enemies

21. Introduction to Computer Network 21 What is Next? Electronic commerce  virtual enterprise Internet entertainment  interactive sitcom World as a small village  community organized according to interests  enhanced understanding among diverse groups Electronic democracy  little people can voice their opinions to the whole world  little people can coordinate their actions  bridge the gap between information haves and have-not’s Electronic terrorism  hacker can bring the whole world to its knee

22. Introduction to Computer Network 22 Industrial Players Telephone companies  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 Equipment companies  switches/routers, chips, optics, computers Software companies

23. Introduction to Computer Network 23 Commercial Internet after 1994 NSF Network Regional ISP America On Line IBM Bartnet Campus Network Joe's Company Stanford Xerox Parc Berkeley NSF Network Internet MCI UUnet SprintNet Modem IBM

24. Introduction to Computer Network 24 Backbone ISP Internet Physical Infrastructure Residential Access  Modem  DSL  Cable modem  Satellite Enterprise/ISP access, Backbone transmission  T1/T3, DS-1 DS-3  OC-3, OC-12  ATM vs. SONET, vs. WDM Campus network  Ethernet, ATM Internet Service Providers  access, regional, backbone  Point of Presence (POP)  Network Access Point (NAP)