1. An Introduction to Computer Networks
Lecture 1: Introduction
University of Tehran
Dept. of EE and Computer Engineering
By:
Dr. Nasser Yazdani
Univ. ov Tehran
Introduction to Computer Network

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

3. Introduction to Computer Network
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.
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Introduction to Computer Network

4. Introduction to Computer Network
Course Materials
Course Web page
visit regularly
Textbook
“Computer Networks, A system approach”. Peterson & Davie 3rd edition
Other useful books
A. Tanenbaum, Computer Networks
R. Stevens, TCP/IP Illustrated (vol 1)
S. Keshav, An Engineering Approach to Computer Networking
Kurose and Ross, Computer Networking
Walrand, Communication Networks, 2nd Ed
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Introduction to Computer Network

5. Introduction to Computer Network
Grading
Homework assignments, around %30
4-5 five homework
Late penalties!
Course involve programming on C/C++ in Unix environment.
Few small quizs around %10
Midterm exam around %30.
Final exam around %30.
Note: There is a %40 cut off on total exam points.
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Introduction to Computer Network

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

7. How to survive this course
Materials sound simple and easy, but they are not.
Do not leave everything to the exam night!.
Not copy the homework!, try them by yourself.
You can read the course by yourself, but the class makes the life for you easier.
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Introduction to Computer Network

8. Introduction to Computer Network
Some Ground Rules
Let’s make this educational and enjoyable.
It’s a big class, I enjoy questions and ideas from the class.
Ask questions and raise points.
Identify yourself when you ask questions.
Listen to other people’s questions.
Be here.
Be here on time.
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Introduction to Computer Network

9. Introduction to Computer Network
Special Warning
This is computer network course not queue theory!
There are not much Mathematics (Attention for EE students!)
There are programming in the course
Still we think the course is not easy. Needs a lot of work.
Indeed, It is in a higher level than just sending signals.
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Introduction to Computer Network

10. Why Study Computer Network?
To graduate!
To get a degree
To be engineer. It is good in the society, for prestige, marriage, etc.
Networking is everything!
It does not matter what you know. It is matter who you know.
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Introduction to Computer Network

11. Introduction to Computer Network
What you Learn?
Insight: key concepts in networking
Protocols
Layering
Resource allocation
Performance evaluation
Knowledge: how the Internet works
Internet architecture
IP protocol suite
Applications (Web, , P2P, …)
Skill: network programming
Socket programming
Designing and implementing protocols
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Introduction to Computer Network

12. Communication as a human being 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.
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Introduction to Computer Network

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

14. Communication elements
Producer, Sender
Speaker (in conversation)
Consumer, Receiver
Listener
They both do have processing-limitation
Message- Talk
Transfer media, like air
Substance
Capacity (very limited)
Delay (considerable)
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Introduction to Computer Network

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

16. 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
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Introduction to Computer Network

17. 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.
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Introduction to Computer Network

18. 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.
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Introduction to Computer Network

19. 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
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Introduction to Computer Network

20. Introduction to Computer Network
Broadcast media
Printing, news papers,
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 reach data.
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Introduction to Computer Network

21. 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.
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Introduction to Computer Network

22. 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 10 Gbps, around160 millions computers in 160 countries
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Introduction to Computer Network

23. 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:
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Introduction to Computer Network

24. Introduction to Computer Network
Recent Growth (by 2004)
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Introduction to Computer Network

25. 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?
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Introduction to Computer Network

26. 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
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Introduction to Computer Network

27. Introduction to Computer Network
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
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Introduction to Computer Network

28. Introduction to Computer Network
What is Next?
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
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Introduction to Computer Network

29. 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
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Introduction to Computer Network

30. Introduction to Computer Network
Industrial Players
Medium companies
own content
Internet Service Providers
Equipment companies
switches/routers, chips, optics, computers
Software companies
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Introduction to Computer Network

31. 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
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Introduction to Computer Network

32. Internet Physical Infrastructure
Backbone
ISP
ISP
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)
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Introduction to Computer Network

33. Introduction to Computer Network
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Introduction to Computer Network

34. Introduction to Computer Network
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Introduction to Computer Network

35. Introduction to Computer Network
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Introduction to Computer Network

36. Introduction to Computer Network
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Introduction to Computer Network

37. Introduction to Computer Network
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Introduction to Computer Network

38. Introduction to Computer Network
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Introduction to Computer Network

39. Introduction to Computer Network
Homework 0
Install Linux on your computer
Try to be professional on Unix if you are not so.
For Communication Engineer: Learn C/C++ programming well on Unix environment.
Your first assignment will come soon!.
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Introduction to Computer Network

40. Introduction to Computer Network
Next Lecture
Computer network foundation.
Read Chapter 1
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Introduction to Computer Network