EECS 122: Introduction to Computer Networks Course Goals...

1EE122, Fall ‘05

EECS 122:Introduction to Computer Networks

Course Goals and Overview

Computer Science DivisionDepartment of Electrical Engineering and Computer Sciences

University of California, BerkeleyBerkeley, CA 94720-1776

2EE122, Fall ‘05

Instructors

� Instructor: Ion Stoica ([email protected]) - Office Hours: W 2-3 PM, 645 Soda Hall

� Textbooks- L. L. Peterson and B. Davie, Computer Networks: A System

Approach, 3nd Edition, Morgan Kaufman, San Francisco, 2003.

- W. R. Stevens, B. Fenner, A. M. Rudoff, Unix Network Programming: The Sockets Networking API, Vol. 1, 3rd Ed., Addison-Wesley, Boston, 2004.

3EE122, Fall ‘05

TAs

� Jana Van Gruenen ([email protected])- Discussion section: Th 11-12 299 Cory

� Rowena Luk ([email protected])- Discussion section: Tu 2-3, 299 Cory

� Murali Rangan ([email protected])- Discussion section: F 10-11 299 Cory

� Artur Rivilis ([email protected])- Discussion section: W 1-2, 299 Cory

� Office hours: TBD

4EE122, Fall ‘05

Overview

� Administrivia� Overview and History of the Internet

5EE122, Fall ‘05

Administrivia

� Course Web page: - http://inst.eecs.berkeley.edu/~ee122/- Check often to get the latest information

� Deadlines- HWs: due 3:50 pm on the indicated date (10 minutes

before lecture)� Exams are closed-book, with open crib sheet� Come to office hours, request an appointment,

communicate by e-mail- We are here to help, including general advice!- TAs first line for help with programming problems

� Give us suggestions/complaints as early as possible

6EE122, Fall ‘05

Course Goals

� Learn the main architectural concepts and technological components of communication networks, with the Internet as the overarching example

- Understand how the Internet works- And why the Internet is the way it is

� Apply what you learned in three mini-class projects

7EE122, Fall ‘05

Class Workload

� Four homeworks spread over the semester- Strict deadlines and due dates (no slip days!)

� Three (mini-)projects- 1st and 3rd are part of a larger project, which involves

implementing a comprehensive network application• C (or C++) required

- 2nd is a simulation project � One midterm exams

- October 17� Final exam

- December 17- Note dates and plan your travel accordingly!

8EE122, Fall ‘05

Grading

� Consultation on HWs is OK, but must hand in own work- Correlation between understanding HWs and doing well on exams

� Course graded to mean of B- Relatively easy to get a B, harder to get an A or a C- 10% A, 15% A-, 15% B+, 20% B, 15% B-, 15% C+, 10% C- A+ reserved for superstars (only 1 or 2 per class)- Mean can shift up for an especially great class

20%Final exam

20%Midterm exam

40%(10% + 10% + 20%)

Projects

20%(5% each)

Homeworks

9EE122, Fall ‘05

Overview

� Administrivia� Overview and History of the Internet

• See http://www.isoc.org/internet/history/ for more details

10EE122, Fall ‘05

What do this two have in Common?

� First printing press� Key idea: splitting up text in

individual components- E.g., lower, upper case letters

� Bible: first mass produced book

Johann Gutenberg(1398-1468)

The Internet

Both lower the cost of distributing information Both lower the cost of distributing information

11EE122, Fall ‘05

What is a Communication Network?(End-system Centric View)

� Network offers one basic service: move information- Bird, fire, messenger, truck, telegraph, telephone, Internet …- Another example, transportation service: move objects

• Horse, train, truck, airplane ...� What distinguish different types of networks?

- The services they provide� What distinguish the services?

- Latency- Bandwidth- Loss rate- Number of end systems- Service interface (how to invoke the service?)- Others

• Reliability, unicast vs. multicast, real-time...

12EE122, Fall ‘05

What is a Communication Network?(Infrastructure Centric View)

� Communication medium: electron, photon� Network components:

- Links – carry bits from one place to another (or maybe multiple places): fiber, copper, satellite, …

- Interfaces – attach devices to links

- Switches/routers – interconnect links: electronic/optic, crossbar/Banyan

- Hosts – communication endpoints: workstations, PDAs, cell phones, toasters

� Protocols – rules governing communication between nodes- TCP/IP, ATM, MPLS, SONET, Ethernet, X.25

� Applications: Web browser, X Windows, FTP, ...

13EE122, Fall ‘05

Network Components (Examples)

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14EE122, Fall ‘05

Types of Networks

� Geographical distance- Local Area Networks (LAN): Ethernet, Token ring, FDDI- Metropolitan Area Networks (MAN): DQDB, SMDS- Wide Area Networks (WAN): X.25, ATM, frame relay- Caveat: LAN, MAN, WAN may mean different things

• Service, network technology, networks� Information type

- Data networks vs. telecommunication networks� Application type

- Special purpose networks: airline reservation network, banking network, credit card network, telephony

- General purpose network: Internet

15EE122, Fall ‘05

Types of Networks

� Right to use- Private: enterprise networks- Public: telephony network, Internet

� Ownership of protocols- Proprietary: IBM System Network Architecture (SNA)- Open: Internet Protocol (IP)

� Technologies- Terrestrial vs. satellite- Wired vs. wireless

� Protocols- IP, AppleTalk, SNA

16EE122, Fall ‘05

The Internet (cont’d)

� Global scale, general purpose, heterogeneous-technologies, public, computer network

� Internet Protocol- Open standard: Internet Engineering Task Force (IETF) as

standard body ( http://www.ietf.org )- Technical basis for other types of networks

• Intranet: enterprise IP network� Developed by the research community

17EE122, Fall ‘05

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, early 00’s)

• replacing telephone network?� Medium for information dissemination

- USENET (1980’s)- WWW (1990’s)

• replacing newspaper, magazine?- Audio, video (late 90’s, early 00’s)

• replacing radio, TV?- File sharing (late 90’s, early 00’s)

18EE122, Fall ‘05

Growth of the Internet

Number of Hosts on the Internet:Aug. 1981 213Oct. 1984 1,024Dec. 1987 28,174 Oct. 1990 313,000 Oct. 1993 2,056,000Apr. 1995 5,706,000

Jan. 1997 16,146,000Jan. 1999 56,218,000Jan. 2001 109,374,000Jan. 2003 171,638,297Jan. 2005 317,646,084

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1981 1985 1989 1993 1997 2001

Data available at: http://www.isc.org/

Estimated number of users: http://www.internetworldstats.com/stats.htm

19EE122, Fall ‘05

Internet vs. Telephone Net

� Strengths- Intelligence at ends- Decentralized control

- Operates over heterogeneous access technologies

� Weaknesses- No differential service- Variable performance delay - New functions difficult to add

since end nodes must be upgraded

- No trusted infrastructure

� Strengths- No end-point intelligence- Excellent voice performance

� Weaknesses- Achieves performance by

overprovisioning resources- Difficult to add new services to

“Intelligent Network” due to complex call model

- Expensive approach for reliability

Internet: “intelligent” edge, “dump” core

Internet: “intelligent” edge, “dump” core

Telephone Net: “dump” edge, “intelligent” core

Telephone Net: “dump” edge, “intelligent” core

20EE122, Fall ‘05

History of the Internet

� 68-70’s: started as a research project, 56 kbps, initially 4 nodes (UCLA, UCSB, SRI, Utah) then < 100 computers

- http://www.cnn.com/2004/TECH/internet/08/29/internet.birthday.ap/index.html

� 80-83: TCP/IP, DNS; 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;

Introduction of Commercial Internet� Today: backbones run at 10 Gbps, close to 200 millions

computers in 150 countries

21EE122, Fall ‘05

The ARPANet

� Paul Baran- RAND Corp, early 1960s- Communications networks

that would survive a major enemy attack

� ARPANet: Research vehicle for “Resource Sharing Computer Networks”

- 2 September 1969: UCLA first node on the ARPANet

- December 1969: 4 nodes connected by phone lines

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22EE122, Fall ‘05

ARPANet Evolves into Internet

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26EE122, Fall ‘05

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27EE122, Fall ‘05

Network “ Cloud”

28EE122, Fall ‘05

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29EE122, Fall ‘05

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30EE122, Fall ‘05

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31EE122, Fall ‘05

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32EE122, Fall ‘05

The Evolution of the Enterprise

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37EE122, Fall ‘05

Services Within the Network: Content Distribution

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38EE122, Fall ‘05

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39EE122, Fall ‘05

Summary

� Course administrative trivia� Internet history and background

EECS 122: Introduction to Computer Networks Course Goals...

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