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

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

3. Introduction to Computer Network
Course Materials
Course Web page
visit regularly
Textbook
اصول شبکه هاي کامپيوتري، عبدالله پوري، انتشارات کردستان
مهندسی اینترنت، احسان ملکیان، انتشارات نص
“Computer Networks, A system approach”. Peterson & Davie 3rd edition
Grading
Midterm 35%
Final 55%
Quiz 10%
Introduction to Computer Network

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

5. Introduction to Computer Network
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.
Introduction to Computer Network

6. 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.
Introduction to Computer Network

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

8. Introduction to Computer Network
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.
Introduction to Computer Network

9. Introduction to Computer Network
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
Introduction to Computer Network

10. Introduction to Computer Network
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.
Introduction to Computer Network

11. Introduction to Computer Network
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.
Introduction to Computer Network

12. Introduction to Computer Network
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
Introduction to Computer Network

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

14. Introduction to 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.
Introduction to Computer Network

15. 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
Introduction to Computer Network

16. Growth of the Internet Number of Hosts on the Internet: Aug. 1981 213
Oct ,024
Dec ,174
Oct ,000
Oct ,056,000
Apr ,706,000
Jul ,540,000
Jul ,249,900
Jul ,288,000
Data available at:
Introduction to Computer Network

17. Introduction to Computer Network
Recent Growth ( )
Introduction to Computer Network

18. 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
(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?
replacing radio, CD, TV?
Introduction to Computer Network

19. Introduction to Computer Network
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
Introduction to Computer Network

20. Introduction to Computer Network
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
Introduction to Computer Network

21. Introduction to Computer Network
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
Introduction to Computer Network

22. Introduction to Computer Network
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
Introduction to Computer Network

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

24. Internet Physical Infrastructure
Backbone
ISP
ISP
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)
Residential Access
Modem
DSL
Cable modem
Satellite
Introduction to Computer Network