CSE 245: Computer Networks and Data Communications http:vista.uconn.edu

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CSE 245 Computer Networks and Data
Communicationshttp//vista.uconn.edu

• Jun-Hong Cui
• 08/29/2006

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Outline

• Course information
• What is a network protocol?
• A brief introduction to the Internet past and
  present
• Summary

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Course Information

• Personnel
• Instructor
• Jun-Hong Cui, jcui_at_cse.uconn.edu, ITEB 267
• Office hours
• Tu/Th 1030am-1130am or by appointments
• Feel free to stop by if you see my door open
• e-mail is the best way to communicate with me
• Teaching assistant
• James Zheng Peng, zheng.peng_at_uconn.edu
• Office hours
• Time TBA
• Location ITEB 230

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Course Information

• Textbook
• Computer Networking A Top-Down Approach
  Featuring the Internet,
• 3/e by Kurose and Ross
• -Buy through Co-Op or On-line
• -Make good use of On-line materials
• Reference books
• Computer Networks,
• 4/e by Andrew Tanenbaum
• Unix Network Programming
• by W. Richard Stevens
• And more (see handout)
• Resource
• On-line resources (using NetID)
• http//vista.uconn.edu
• Class discussion forum
• Check WebCT (class discussions)

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What Are the Goals of This Course?

• Understand how Internet works
• Its philosophy
• Its protocols and mechanisms
• Learn network programming
• And have fun!

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What Will We Cover?

• Introduction (3 lectures)
• Internet architecture and design philosophy
• Applications (5 lectures)
• HTTP, Email, DNS socket programming ( C
  programming)
• transport services (5 lectures)
• reliability congestion control transport
  protocols TCP/UDP
• network services (5 lectures)
• routing network protocols IP/IPv6
• link and physical layers (5 lectures)
• multiple access ARP Ethernet, hubs and bridges
• wireless mobile networks, multimedia networking
  network security (if time permits)

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What Do You Need To Do?

• Your prerequisites
• basic concepts of operating systems
• programming C/C (tested by proj0)
• Unix/Linux system experience
• probabilities, and basic algorithms
• Your workload
• textbook reading for every lecture ()
• assignments
• 5 homework assignments
• 3 programming projects
• two mid-term exams, and one final exam

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What Do You Need To Do?

• Homework Do on your own
• Programming projects
• Proj. 0--- C/C Programming (not graded)
• Proj. 1--- HTTP Client (group work)
• Proj. 2--- HTTP Server (group work)
• Proj. 3--- Routing Simulation
• Can do advanced part for extra credits
• Proj. 1 and Proj. 2 can be done in a small group
  (up to 2 people), and others are individual work
• Late policy
• 20 deduction (1 day), 40 (2 days), 80 (3
  days),

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Grading

• More important is what you learn than the grades

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Academic Policy

• Homework and projects should be done on your own
  unless specified as group work
• In any homework or project, copying from other
  students (or groups) or solution books are
  prohibited. Refer to handout for details.
• We follow the University Policy on Academic
  Integrity!!!

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Class Attendance and Computers

• Attendance in class
• Is Responsibility of each Student
• Absence may Result in Missing Hint/Clarification/E
  rror on Homework or Projects
• May Announce Change in Due Date or Exam Date
• I Might NOT Make ALL information to WebCT
• Computers for projects
• Use Unix/Linux machines in ECS (TA grading)
• Unix/Linux labs in ITEB and Engineering II
• Apply for an ECS Unix/Linux account on-line
• Use SSH to remotely login those Unix/Linux boxes
• Test on these machines before you hand in your
  projects
• More info http//www.engr.uconn.edu/ecs/linux/

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Class Survey

• Please take the class survey
• help me to determine your background
• help me to determine depth and topics
• any suggestions on topics and schedule
• Hand in at the end of the class

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Questions?
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Outline

• Course information
• What is a network protocol?
• A brief introduction to the Internet past and
  present
• Summary

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What is a Network Protocol?

• A network protocol defines the format and the
  order of messages exchanged between two or more
  communicating entities, as well as the actions
  taken on the transmission and/or receipt of a
  message or other event.

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An Example Simple Mail Transfer Protocol (SMTP)

• Messages from a client to a mail server
• HELO
• MAIL FROM ltaddressgt
• RCPT TO ltaddressgt
• DATAltThis is the text end with a line with a
  single .gt
• QUIT
• Messages from a mail server to a client
• status code
• The first digit of the response broadly indicates
  the success, failure, or progress of the previous
  command.
• 1xx - Informative message
• 2xx - Command ok
• 3xx - Command ok so far, send the rest of it.
• 4xx - Command was correct, but couldn't be
  performed for some reason.
• 5xx - Command unimplemented, or incorrect, or a
  serious program error occurred.
• content

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Internet Standardization Process

• All standards of the Internet are published as
  RFC (Request for Comments)
• but not all RFCs are Internet Standards !
• available http//www.ietf.org
• A typical (but not the only) way of
  standardization
• Internet draft
• RFC
• Proposed standard
• Draft standard (requires 2 working
  implementations)
• Internet standard (declared by Internet
  Architecture Board)

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Outline

• Course information
• What is a network protocol?
• A brief introduction to the Internet
• past
• present
• Summary

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A Brief History of the Internet

• 1961
• Kleinrock - queueing theory shows effectiveness
  of packet-switching (telephone network circuit
  switching)
• 1968
• Bolt Beranek and Newman, Inc. (BBN) was awarded
  Packet Switch contract to build Interface Message
  Processors (IMPs) for ARPANET

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A Brief History of the Internet

• 1969
• ARPANET commissioned 4 nodes, 50kbps

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Initial Expansion of the ARPANET
Dec. 1969
March 1971
July 1970
Apr. 1972
Sep. 1972
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Multiple Networks

• 1974 Initial design of TCP to connect multiple
  networks
• 1986 NSF builds NSFNET as backbone, links 6
  supercomputing centers, 56 kbps this allows an
  explosion of connections, especially from
  universities
• 1987 10,000 hosts
• 1988 NSFNET backbone upgrades to 1.5Mbps
• 1989 100,000 hosts WELCOME by Leonard
  Kleinrock

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Web and Commercialization of the Internet

• 1990 ARPANET ceases to exist
• 1991 NSF lifts restrictions on the commercial
  use of the Net Berners-Lee of European
  Organization for Nuclear Research (CERN) released
  World Wide Web
• 1992 1 million hosts
• 1994 NSF reverts back to research network
  (vBNS) the backbone of the Internet consists of
  multiple private backbones
• Today backbones run at 10Gbps, 100s millions
  computers in 150 countries

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Growth of the Internet in Terms of Number of
Hosts

• Number of Hosts on the Internet
• Aug. 1981 213
• Oct. 1984 1,024
• Dec. 1987 28,174
• Oct. 1990 313,000
• Jul. 1993 1,776,000
• Jul. 1996 19,540,000
• Jul. 2000 93,047,000
• Jul. 2002 162,128,493

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Outline

• Course information
• What is a network protocol?
• A brief introduction to the Internet
• past
• present
• Summary

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Internet Physical Infrastructure
Local/Regional ISP
BackboneNational ISP
Local/RegionalISP

• Residential Access
• Modem
• DSL
• Cable modem

• Access to ISP, Backbone transmission
• T1/T3, OC-3, OC-12
• ATM, SONET, WDM

• Internet Service Providers
• Local/Regional/ National
• They exchange packets at Point of Presence (POP)

• Campus network access
• Ethernet
• FDDI
• Wireless

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ATT Global Backbone IP Network
From http//www.business.att.com
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From ATT web site.
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Summary

• Course information
• Concept of network protocol
• The past
• The Internet started as ARPANET in late 1960s
• The initial link bandwidth was 50 kbps
• The number of hosts at the end of 1969 was 4
• Current
• The number of hosts connected to the Internet
  grows at an exponential speed
• The backbone speed of the current Internet is
  about 10 Gbps
• The number of hosts attached to the Internet in
  July 2002 was about 162 millions

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Hands-on Exercises

• Read the manual of ping and traceroute (or
  tracert), and try them on an ECS machine
• /bin/ping ltmachine_namegt
• /usr/sbin/traceroute ltmachine_namegt
• Look at the web sites of the routers you see
  through traceroute
• Have fun
• Check WebCT Vista for Proj. 0
• Buy your textbook on-line (cheaper faster)
• Dot not forget to find your group members!