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EECS 122: Introduction to Computer Networks

Course Goals and Overview

Computer Science Division

Department of Electrical Engineering and Computer Sciences

University of California, Berkeley

Berkeley, CA 94720-1776

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Instructors

Instructors- Randy Katz (randy@cs.Berkeley.edu), Office Hours: Tu 1-2 PM, W

11-12 noon, and by appointment, 637 Soda Hall

- Ion Stoica (istoica@cs.Berkeley.edu), Office Hours: M 5-6 PM, W 4-5 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.

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TAs

Byung-Gon Chun, bgchun@cs.Berkeley.eduTu 4-5 PM, room TBD

Xuanming Dong, xuanming@eecs.Berkeley.edu Time and room TBD

Ling Huang, hling@cs.Berkeley.eduTu 2-3 PM, room TBD

Sonesh Surana, sonesh@cs.Berkeley.eduTime and room TBD

For final office hour schedule, please see the web

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Overview

Administrivia Overview and History of the Internet

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Administrivia

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

Deadlines- HWs: due 10:50 am 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

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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

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Class Workload

NOTE: EE122 is a 4 unit course starting this semester! 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 Two midterm exams

- September 30 and November 4 Final exam

- December 16

- Note dates and plan your travel accordingly!

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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

Homeworks 20%

(5% each)

Projects 40%

(10% + 10% + 20%)

Midterm exams 20%

(10% each)

Final exam 20%

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Overview

Administrivia Overview and History of the Internet

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

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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...

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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, ...

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Network Components (Examples)

Fibers

Coaxial Cable

Links Interfaces Switches/routers

Ethernet card

Wireless card

Large router

Telephoneswitch

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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

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Types of Networks

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

Ownership of protocols- Proprietary: SNA- Open: IP

Technologies- Terrestrial vs. satellite- Wired vs. wireless

Protocols- IP, AppleTalk, SNA

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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

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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

- Heterogeneous devices

- Excellent voice performance Weaknesses

- Achieves performance by overallocating resources

- Difficult to add new services to “Intelligent Network” due to complex call model

- Expensive approach for reliability

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History of the Internet

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

- 2 September 2004/35th Anniversary of the Internet- http://www.cnn.com/2004/TECH/internet/08/29/internet.birthda

y.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

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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

SRI940

UCLASigma 7

UCSBIBM 360

UtahPDP 10

IMPs

BBN team that implementedthe interface message processor

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ARPANet Evolves into Internet

Web HostingMultiple ISPsInternet2 BackboneInternet Exchanges

Application HostingASP: Application Service ProviderAIP: Application InfrastructureProvider (e-commerce tookit, etc.)

ARPANetSATNetPRNet

TCP/IP NSFNet Deregulation &Commercialization

1965 1975 1985 1995 2005

WWW

ISPASPAIP

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Parallel BackbonesQwest IP Backbone (Late 1999)Digex BackboneGTE Internetworking Backbone

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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

Jan. 1997 16,146,000

Jan. 1999 56,218,000

Jan. 2001 109,374,000

Jan. 2003 171,638,297

Jan. 2004 233,101,481

1

10

100

1000

10000

100000

1000000

10000000

100000000

1000000000

1981 1985 1989 1993 1997 2001

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

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

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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? Medium for information dissemination

- USENET (1980’s)- WWW (1990’s)

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

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

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BackboneISP

ISP

Internet Physical Infrastructure

Residential Access

- Modem- DSL- Cable

modem- Satellite

Enterprise/ISP access, Backbone transmission

- T1/T3, DS-1 DS-3

- OC-3 … OC-76

- ATM vs. SONET, vs. WDM

Campus network- Ethernet, ATM

Internet Service Providers- access, regional, backbone

- Point of Presence (POP)

- Network Access Point (NAP)

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Network “Cloud”

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RegionalNet

Regional Nets + Backbone

RegionalNet Regional

Net

RegionalNet Regional

Net

RegionalNet

Backbone

LAN LANLAN

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ISP

Backbones + NAPs + ISPs

ISP

ISPISP

BusinessISP

ConsumerISP

LAN LANLAN

NAPNAP

Backbones

Dial-up

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CoreNetworks

Covad

Core Networks + Access Networks

@home

ISPCingular

Sprint AOL

LAN LANLAN

NAP

Dial-up

DSLAlways on

NAP

CableHead Ends

CellCell

Cell

SatelliteFixed Wireless

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Covad

Computers Inside the Core

@home

ISPCingular

Sprint AOL

LAN LANLAN

NAP

Dial-up

DSLAlways on

NAP

CableHead Ends

CellCell

Cell

SatelliteFixed Wireless

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The Evolution of the Enterprise

Private CorporateNetwork

Dedicated facilities/computer centers

Dedicated applications/3rd party DBMS

E.g., Oracle

Late-1980sInternal users

Limited customer/external access

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The Evolution of the Enterprise

Private CorporateNetwork

Dedicated facilities/computer centers

Outsourced“Enterprise Resource

Planning” Appse.g., PeopleSoft, BAAN

1995Internal users

Limited customer/external access

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The Evolution of the Enterprise

OutsourcedWeb Hosting

Dedicated FacilityOutsourcedERP Apps

1997Internal users

Internet

External Customers

Virtual Private Network

ISP Mesh

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The Evolution of the Enterprise

OutsourcedWeb Hosting

Dedicated FacilityOutsourcedERP Apps

1997Internal users

Internet

External Customers

Virtual Private Network

ISPMesh

InternetServices

SearchCachingAdsEComm

Portal

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The Evolution of the Enterprise

ApplicationsService Provider

1999

Customers

Content Delivery “Net”

3rd PartyFacilities Mgmt

Caching +Media Servers

InternetServices

SearchCacheAdsEComm

OutsourcedWeb Hosting

Portal

ISP Mesh

VPNs

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Services Within the Network: Content Distribution

“Internet Grid”Parallel Network BackbonesInternet Exchange Points

Co-Location

Scalable Servers

WebCaches

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P2P Services in the Internet:Napster, Gnutella, Freenet, …

. . .

Madonna Like a Virgin

Madonna Material Girl

. . .

Directory Service

Register my copy

Find me a copy

Look here

Grid computing: sharing resources/enabling collaboration

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Services Within the Network:Streaming Media

Clients

Broadcasters

Content Broadcast

ManagementPlatform and

Tools

Steve McCanne

EdgeServers

Load Balancing ThruServer Redirection;

Content BroadcastNetwork

Content DistributionThrough MulticastOverlay Network

RedirectionFabricInter-ISP Redirection

Peering

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Summary

Course administrative trivia Internet history and background