An introduction to computer networks
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An Introduction to Computer Networks. Lecture 1: Introduction. University of Tehran Dept. of EE and Computer Engineering By: Dr. Nasser Yazdani. Outline. Agenda Policy, Grading, reading materials, etc. Communication. Overview and history of the Internet. Agenda.

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An Introduction to Computer Networks

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An introduction to computer networks

An Introductionto Computer Networks

Lecture 1: Introduction

University of Tehran

Dept. of EE and Computer Engineering


Dr. Nasser Yazdani

Introduction to Computer Network



  • Agenda

  • Policy, Grading, reading materials, etc.

  • Communication.

  • Overview and history of the Internet

Introduction to Computer Network



  • 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.

Introduction to Computer Network

Course materials

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

Introduction to Computer Network



  • 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.

  • There is a %40 cut off on total exam points.

Introduction to Computer Network



  • General knowledge in Computer engineering.

  • C programming.

  • Knowledge of UNIX (LINUX) system and programming.

  • Fluency in English, specially reading.

Introduction to Computer Network

How to survive this course

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.

Introduction to Computer Network

Some ground rules

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.

Introduction to Computer Network

Communication as a human being need

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.

Introduction to Computer Network

Primary communication means

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.

Introduction to Computer Network

Communication elements

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)

Introduction to Computer Network

Type of communication

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.

Introduction to Computer Network

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

    • Encoding message

Introduction to Computer Network

Next step mailing

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

New wave telegraph

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



  • 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

Broadcast media

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

    • All like radio, but with reach data.

Introduction to Computer Network

Computer network

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

History of the internet

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

Introduction to Computer Network

Growth of the internet

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:

Introduction to Computer Network

Recent growth 1991 2000

Recent Growth (1991-2000)

Introduction to Computer Network

Recent growth by 2004

Recent Growth (by 2004)

Introduction to Computer Network

Services provided by the internet

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?

Introduction to Computer Network

Today s vision

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

What is next

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

Introduction to Computer Network

What is next1

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

Introduction to Computer Network

Industrial players

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

Introduction to Computer Network

Industrial players1

Industrial Players

  • Medium companies

    • own content

  • Internet Service Providers

  • Equipment companies

    • switches/routers, chips, optics, computers

  • Software companies

Introduction to Computer Network

Commercial internet after 1994

Commercial Internet after 1994

Joe's Company



Regional ISP

Campus Network


Xerox Parc


America On Line


NSF Network


NSF Network


Internet MCI


Introduction to Computer Network

Internet physical infrastructure

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)

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

An introduction to computer networks

Introduction to Computer Network

Homework 0

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!.

Introduction to Computer Network

Next lecture

Next Lecture

  • Computer network foundation.

  • Read Chapter 1

Introduction to Computer Network

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