Transcript Introduction - Ilam university

Computer Networks
Ilam University
Dr. Mozafar Bag-Mohammadi
Introduction to Computer Network
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Outline
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Agenda
Policy, Grading, reading materials, etc.
Communication.
Overview and history of the Internet
Introduction to Computer Network
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Course Materials
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Course Web page
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Textbook
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visit regularly
“Computer Networks, A system approach”. Peterson & Davie
4th edition
‫ انتشارات نص‬،‫ احسان ملکیان‬،‫ مهندسی اینترنت‬
Grading
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Midterm 35%
Final 50%
homework 10%
%5 ‫) قرآن قبل از امتحان پایان ترم‬30 ‫حفظ یک حزب (غیر از جزء‬
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Prerequisition
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General knowledge in Computer.
Fluency in English, specially reading.
C++ programming.
Knowledge of UNIX (LINUX) system and
programming.
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Communication as need.
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Base of community
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Transferring data, knowledge, experience
among people
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Collection of trees is not a community.
Base of civilization.
Psycological need.
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Love, affection.
Just talking.
Releasing someone.
Base of Culture.
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Primary Communication means
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Language
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Body Language,
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Conventions
Meta language.
Universal.
Problems:
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Limited in Time and space.
We are struggling all the history to overcome
these limitation.
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Communication elements
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Producer, Sender
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Consumer, Receiver
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Speaker
Listener
They both do processing and have limitation
Message - Talk
Transfer media, like air
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Substance
Capacity
Delay
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Type of communication
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One to one
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One to many
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Talks, conferencing
Many to Many
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Direct talk.
Like mass media, newspaper.
Domain of communication
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Small, primary society
Medium, more developed society.
Large, more advance society.
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First Step- Writing
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One of the most important human being
invention. (Why?)
Overcome the primary limitations.
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Time: By writing it down.
Space: Distributing more copies, library, post, etc.
Problems:
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Indirect Communication, Through paper.
Slow in producing and consuming
Need proficiency
Encoding message
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Next Step- Mailing
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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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New wave- Telegraph
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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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Telephone
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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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Broadcast media
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Printing, newspapers,
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Radio
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Easy to reproduce the same data.
Easy to distribute message.
Slow in producing and contribution.
Easy to distribute message.
Fast in producing and contribution of message.
Limited of type of message, only voice.
TV
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All like radio, but with richer data.
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Computer Network
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Fast in producing, processing, distributing
and consuming messages.
No limitation in time and space.
Support different type of communication.
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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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History of the Internet
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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
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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
Jul. 2001 117,288,000
1000000000
100000000
10000000
1000000
100000
10000
1000
100
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1981 1984 1987 1990 1993 1996 1999
Data available at: http://www.netsizer.com/
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Recent Growth (1991-2000)
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Services Provided by the
Internet
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Shared access to computing resources
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Shared access to data/files
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telnet (1970’s(
FTP, NFS, AFS (1980’s(
Communication medium over which people interact
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email (1980’s(, on-line chat rooms, instant messaging (1990’s(
audio, video (1990’s(
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replacing telephone network?
A medium for information dissemination
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USENET (1980’s(
WWW (1990’s(
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replacing newspaper, magazine?
audio, video (1990’s(
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replacing radio, CD, TV?
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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,
broker, mother, son, friends, enemies
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Today’s Vision
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Electronic commerce
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Internet entertainment
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community organized according to interests
enhanced understanding among diverse groups
Electronic democracy
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interactive sitcom
World as a small village
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virtual enterprise
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
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hacker can bring the whole world to its knee
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Industrial Players
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Telephone companies
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Cable companies
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own content
Internet Service Providers
Equipment companies
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own right of way to lay down more wires
Medium companies
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alternative communication links
Utility companies: power, water, railway
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own access links
Wireless/Satellite companies
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own long-haul and access communication links, customers
switches/routers, chips, optics, computers
Software companies
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What is Next?
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Who knows?!!
Use your imagination
If you can predict something here you will be
a winner
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Peer to peer
Ebay
Google
weblogs
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Commercial Internet after
1994
Joe's Company
Campus Network
Berkeley
Stanford
Regional ISP
Bartnet
Xerox Parc
SprintNet
America On Line
UUnet
NSF Network
IBM
NSF Network
Modem
Internet MCI
IBM
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Internet Physical
Infrastructure
ISP
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Residential
Access
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Modem
DSL
Cable
modem
Satellite
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Backbone
ISP
Enterprise/ISP access,  Campus network
Backbone transmission  Ethernet, ATM
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T1/T3, DS-1 DS-3
OC-3, OC-12
ATM vs. SONET, vs.
WDM
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Internet Service Providers
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Introduction to Computer Network
access, regional,
backbone
Point of Presence (POP)
Network Access Point
(NAP)
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