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

2. Introduction to Computer Network2 Outline Agenda Policy, Grading, reading materials, etc. Communication. Overview and history of the Internet

3. Introduction to Computer Network3 Course Materials Course Web page visit regularly Textbook “Computer Networks, A system approach”. Peterson & Davie 4th edition مهندسی اینترنت، احسان ملکیان، انتشارات نص Grading Midterm 35% Final 50% homework 10% حفظ یک حزب (غیر از جزء 30) قرآن قبل از امتحان پایان ترم 5%

4. Introduction to Computer Network4 Prerequisition General knowledge in Computer. Fluency in English, specially reading. C++ programming. Knowledge of UNIX (LINUX) system and programming.

5. Introduction to Computer Network5 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.

6. Introduction to Computer Network6 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.

7. Introduction to Computer Network7 Communication elements Producer, Sender Speaker Consumer, Receiver Listener They both do processing and have limitation Message - Talk Transfer media, like air Substance Capacity Delay

8. Introduction to Computer Network8 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.

9. Introduction to Computer Network9 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

10. Introduction to Computer Network10 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.

11. Introduction to Computer Network11 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.

12. Introduction to Computer Network12 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

13. Introduction to Computer Network13 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.

14. Introduction to Computer Network14 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.

15. Introduction to Computer Network15 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, 200 millions computers in 150 countries

16. Introduction to Computer Network16 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/

17. Introduction to Computer Network17 Recent Growth (1991-2000)

18. Introduction to Computer Network18 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?

19. Introduction to Computer Network19 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

20. Introduction to Computer Network20 Today’s Vision 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

21. Introduction to Computer Network21 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

22. Introduction to Computer Network22 What is Next? Who knows?!! Use your imagination If you can predict something here you will be a winner Peer to peer Ebay Google weblogs

23. Introduction to Computer Network23 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 Network24 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)