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Introduction Lecture 1 cs193i – Internet Technologies Summer 2004 Stanford University Outline What is the Internet? Where did it come from? What are we going to discuss in cs193i? Break Networking basics Physical Infrastructure The Ever-changing Internet

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introduction lecture 1

IntroductionLecture 1

cs193i – Internet Technologies

Summer 2004

Stanford University

outline
Outline
  • What is the Internet?
  • Where did it come from?
  • What are we going to discuss in cs193i?
  • Break
  • Networking basics
  • Physical Infrastructure
the ever changing internet
The Ever-changing Internet

Different colors based on IP address

http://research.lumeta.com/ches/map

what is the internet
What is the Internet?
  • WWW
  • Video conferencing
  • ftp
  • telnet
  • Email
  • Instant messaging
what is the internet5
What is the Internet?
  • WWW
  • Video conferencing
  • ftp
  • telnet
  • Email
  • Instant messaging

A communication infrastructure

Usefulness is in exchanging information

slide6

“On-line interactive communities... will be communities not of common location, but of common interest.... the total number of users...will be large enough to support extensive general purpose [computers]. All of these will be interconnected by telecommunications channels... [to] constitute a labile network of networks--ever changing in both content and configuration.”

J. C. R. Licklider

where did it come from
Where Did It Come From?
  • It was invented by Al Gore. JUST KIDDING!
  • Early 1960’s - DARPA (ARPA in 1960’s) project headed by Licklider
  • Late 1960’s - ARPANET & research on packet switching by Roberts
    • First node installed by BBN at UCLA in September 1969
    • 1969 - Four host computers (UCLA, SRI, UCSB, University of Utah)

Get more info at:

http://www.isoc.org/internet/history/

http://www.packet.cc/internet.html

arpanet 1980
ARPANET, 1980

http://mappa.mundi.net/maps/maps_001/

history of the internet
History of the Internet
  • 1969 - RFCs begun by S. Crocker (http://rfc.sunsite.dk/)
  • 1972 - Email by Ray Tomlinson & Larry Roberts
  • 1970’s - TCP by Vint Cerf & Bob Kahn
    • Evolved into TCP/IP, and UDP
  • 1980s – Hardware Explosion (LANs, PCs, and workstations)
    • 1983 – Ethernet by Metcalfe
  • DNS – Distributed and scalable mechanism for resolving host names into IP addresses
  • UC Berkeley implements TCP/IP into Unix BSD
  • 1985 – Internet used by researchers and developers
history of the internet10
History of the Internet
  • Tim Berners-Lee at CERN in 1989
    • Proposal for WWW in 1990
    • First web page on November 13, 1990
  • Hypertext - Text that contains links to other text.
    • Ted Nelson’s Xanadu
    • Vannevar Bush’s Memex

(http://www.theatlantic.com/unbound/flashbks/computer/bushf.htm)

  • W3C

Get more info at:

http://www.isoc.org/internet/history/

what will cs193i cover
What will cs193i cover?
  • Basic Networking Issues
  • Network Interoperability and Standards
    • TCP/IP
  • Sockets and Client/Server Structures
  • Services
  • Applications
    • HTML, HTTP, CGI, Servlets
  • Security and Privacy
  • Advanced Topics
course staff
Kelly A. Shaw

Instructor

Professor at Univ. of Richmond in Fall

PhD Candidate w/ Distinction in Teaching

BS from Duke University

Gates 255

Office hours: MW 2-4pm

Silas Boyd-Wickizer

Teaching Assistant

Office hours: TTh 4-6pm

Sweet hall

Course Staff
meeting times
Meeting Times
  • Lecture
    • MW 4:15-6:05 McCullough 115
    • Broadcast Live on E3
    • Stanford Online
  • Two review sessions - TBA
    • Perl
    • Java
reading materials
Reading Materials
  • No required textbook
  • Recommended:
    • Core Web Programming by Marty Hall and Larry Brown.
  • Handouts
    • On-line only
course details
Course Details
  • Grading
    • 50% Homework (4 assignments)
    • 5% Labs (4 labs)
    • 10% Midterm
    • 30% Final
    • 5% Class participation (if not SCPD)
  • May work in groups of 1 or 2 students
  • C/NC students
homework assignments
Homework Assignments
  • HW #1
    • POP email client
    • Server/Client pair with authentication
  • HW #2
    • Simple Web Client
    • Simple Web Server
  • HW #3
    • CGI Programming

(e.g. for maintaining Netflix Movie Queue)

  • HW #4
    • Java / JSP / Servlets and Javascript
    • Amazon.edu Bookstore
administrative details
Administrative Details
  • Contacting staff
    • cs193i-sum0304-staff@lists.stanford.edu
  • Newsgroup
    • su.class.cs193i
  • Grading/testing on Leland systems
  • Honor Code
bits and bytes
Bits and Bytes
  • Computer Data is stored in Binary
    • Binary Digits (bits) Base 2 representation

1011100001101010

  • Every 8 bits == 1 Byte

10111000 01101010 (2 bytes (once known as octet))

  • Hexadecimal == Base 16 representation

1011 1000 0110 1010

B 8 6 A

  • Decimal == Base 10 (we have 10 fingers)

0...9, A = 10, B= 11, C = 12, D = 13, E = 14, F = 15

bits and bytes21
Bits and Bytes
  • Kilobyte (2^10=1024 Bytes, 10^3=1000 Bytes in networking)
  • Megabyte (2^20 Bytes, 10^6 in Networking)
  • Gigabyte (2^30 Bytes, 10^9 in Networking)
  • Terabyte (2^40, 10^12)
  • Petabyte (2^50, 10^15)
performance latency and bandwidth

link

bandwidth

latency

Performance: Latency and Bandwidth
  • Latency
    • How long minimum communication takes in seconds (s)
    • Round trip vs. single trip
    • More difficult to overcome than bandwidth
  • Bandwidth
    • Number of bits per time unit usually seconds (bps)
any to any communication
Any-to-Any Communication
  • n2 Network Effect (Metcalfe’s Law)
    • Total utility of system proportional to n2
    • Think about Orkut, MSN Messenger
babel
Babel
  • Internet consists of many different types of networks
    • Ethernet
    • Token ring
  • Different types of operating systems and other software
  • How do they work together?
    • Standards
divide work into layers

01010

01010

0 1 0 1 0

01010

01010

a

b

Divide Work into Layers
  • make network simple and reliable
  • connect segments, address (locating points on graph) and route (navigating graph)
  • physically encode bits on “wire”
sending data along wires
Sending Data Along Wires
  • Connection-oriented
    • Circuit switched
      • Persistent connection set up between sender and receiver
    • Example: telephone system
  • Connectionless
    • Packet switched
      • Data partitioned into packets and

sent individually from sender to receiver

      • Reassembled at receiver
comparison of switching technologies
Circuit switched

Advantages

Only route once

Latency and bandwidth constant

Disadvantages

Idle resources unavailable for other connections

Large setup time

Single point of failure

Distributed state

Packet switched

Advantages

Efficient use of wires

Small startup overhead

Disadvantages

Route each packet

Per packet overhead

Bursty

Comparison of Switching Technologies
ethernet
Ethernet
  • Bob Metcalfe at Xerox PARC
  • Used for local area networks (LANs)
    • Physically near one another
    • 200 computers within 100 meters
  • Broadcast medium
    • Single wire connects all computers
      • Each computer has unique 48-bit MAC address
    • All computers constantly listen
  • “Carrier Sense, Multiple Access with Collision Detect”
    • Sender waits until wire unused before sending
    • If hears collision, stops, waits random time, retransmits
ethernet properties
Ethernet Properties
  • Shared
  • Distributed (not Centralized)
  • Insecure
  • Unpredictable Latency & Bandwidth
  • But it works!
    • Under light load (<30%), appears to be point-to-point
alternative to ethernet token ring
Alternative to Ethernet:Token Ring
  • Alternative introduced by IBM (1980s)
  • “Passing the Conch Shell”
next time
Next Time
  • Network Layer
    • IP
  • End-to-End or Transport Layer
    • TCP