Univ. ov Tehran Introduction to Computer Net work
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An Introduction
An Introduction
to
Computer Networks
Computer Networks
University of Tehran
Dept. of EE and Computer Engineering
By:
Dr. Nasser Yazdani
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Outline
Outline
Agenda
Policy, Grading, reading materials, etc.
Communication.
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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
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Course Materials
Course Web page
http://ece.ut.ac.ir/classpages/Networks/
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
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Grading
Homework assignments, around %30
3-4 five homework
A small project.
Severe late penalties!
Course involve programming on C/C++ in
Unix environment.
Few small quizs around %10
Midterm exam around %30.
Final exam around %30.
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Prerequisition
General knowledge in Computer
engineering.
C programming.
Knowledge of UNIX (LINUX) system
and programming.
Fluency in English, specially
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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
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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.
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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.
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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
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Communication elements
Producer, Sender
Speaker (in conversation)
Consumer, Receiver
Listener
They both do have processing-limitation
Message- Talk
Transfer media, like air
Substance
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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.
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First Step- Writing
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
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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
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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)
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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
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Broadcast media
Printing, news papers,
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
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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.
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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
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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
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Recent Growth
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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)
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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,
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What is Next?
Electronic commerce
virtual enterprise
Internet entertainment
interactive sitcom
World as a small village
community organized according to
interests
enhanced understanding among
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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
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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
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Industrial Players
Medium companies
own content
Internet Service Providers
Equipment companies
switches/routers, chips, optics,
computers
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Commercial Internet after
1994
NSF Network Regional ISP
America On Line
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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)
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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
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