Transcript 01-Overview - Berkeley AI Materials

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
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Instructors
- Randy Katz ([email protected]), Office Hours: Tu 1-2 PM, W
11-12 noon, and by appointment, 637 Soda Hall
- Ion Stoica ([email protected]), Office Hours: M 5-6 PM, W
4-5 PM, 645 Soda Hall
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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
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Byung-Gon Chun, [email protected]
Tu 4-5 PM, room TBD
Xuanming Dong, [email protected]
Time and room TBD
Ling Huang, [email protected]
Tu 2-3 PM, room TBD
Sonesh Surana, [email protected]
Time and room TBD
For final office hour schedule, please see the web
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Overview
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Administrivia
Overview and History of the Internet
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Administrivia
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Course Web page:
- http://inst.eecs.berkeley.edu/~ee122/
- Check often to get the latest information
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Deadlines
- HWs: due 10:50 am on the indicated date (10 minutes
before lecture)
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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
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Give us suggestions/complaints as early as
possible
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Course Goals
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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
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Apply what you learned in three mini-class projects
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Class Workload
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NOTE: EE122 is a 4 unit course starting this semester!
Four homeworks spread over the semester
- Strict deadlines and due dates (no slip days!)
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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
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Two midterm exams
- September 30 and November 4
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Final exam
- December 16
- Note dates and plan your travel accordingly!
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Grading
Homeworks
Projects
Midterm exams
Final exam
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20%
(5% each)
40%
(10% + 10% + 20%)
20%
(10% each)
20%
Consultation on HWs is OK, but must hand in own work
- Correlation between understanding HWs and doing well on exams
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Course graded to mean of B
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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
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Overview
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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)
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Network offers one basic service: move information
- Bird, fire, messenger, truck, telegraph, telephone, Internet …
- Another example, transportation service: move objects
• Horse, train, truck, airplane ...
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What distinguish different types of networks?
- The services they provide
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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)
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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
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Protocols – rules governing communication between nodes
- TCP/IP, ATM, MPLS, SONET, Ethernet, X.25
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Applications: Web browser, X Windows, FTP, ...
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Network Components (Examples)
Links
Interfaces
Fibers
Ethernet card
Switches/routers
Large router
Wireless card
Coaxial Cable
Telephone
switch
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Types of Networks
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Geographical distance
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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
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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
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Right to use
- Private: enterprise networks
- Public: telephony network, Internet
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Ownership of protocols
- Proprietary: SNA
- Open: IP
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Technologies
- Terrestrial vs. satellite
- Wired vs. wireless
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Protocols
- IP, AppleTalk, SNA
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The Internet (cont’d)
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Global scale, general purpose, heterogeneoustechnologies, 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
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Developed by the research community
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Internet vs. Telephone Net
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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
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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
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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
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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
SRI
940
UCSB
IBM 360
IMPs
Utah
PDP 10
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UCLA
Sigma 7
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BBN team that implemented
the interface message processor
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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ARPANet Evolves into Internet
ARPANet
SATNet
PRNet
1965
TCP/IP
1975
Web Hosting
Multiple ISPs
Internet2 Backbone
Internet Exchanges
NSFNet
Deregulation & ISP
Commercialization ASP
AIP
WWW
1985
1995
2005
Application Hosting
ASP: Application Service Provider
AIP: Application Infrastructure
Provider (e-commerce tookit, etc.)
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Digex
Backbone
Qwest
IP
Backbone
(Late
1999)
GTE
Internetworking
Backbone
Parallel Backbones
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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
1000000000
100000000
10000000
1000000
100000
10000
1000
100
10
1
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
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Shared access to computing resources
- telnet (1970’s)
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Shared access to data/files
- FTP, NFS, AFS (1980’s)
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Communication medium over which people interact
- email (1980’s), on-line chat rooms, instant messaging (1990’s)
- audio, video (1990’s)
• replacing telephone network?
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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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Internet Physical Infrastructure
ISP
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Residential
Access
- Modem
- DSL
- Cable
modem
- Satellite
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Backbone
ISP
Enterprise/ISP access,
Backbone transmission
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- T1/T3, DS-1 DS-3
- OC-3 … OC-76
- ATM vs. SONET, vs.
WDM
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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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Regional Nets + Backbone
Regional
Net
Regional
Net
Regional
Net
Backbone
Regional
Net
Regional
Net
LAN
LAN
Regional
Net
LAN
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Backbones + NAPs + ISPs
ISP
ISP
ISP
NAP
Backbones
Business
ISP
LAN
LAN
ISP
NAP
Consumer
ISP
LAN
Dial-up
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Core Networks + Access Networks
DSL
Always on
Cable
Head Ends
@home
Covad
Cingular
Cell
Cell
Cell
LAN
NAP
Core
Networks
NAP
ISP
Satellite
Fixed Wireless
Sprint
LAN
AOL
LAN
Dial-up
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Computers Inside the Core
DSL
Always on
Cable
Head Ends
@home
Covad
Cingular
Cell
Cell
Cell
LAN
NAP
NAP
ISP
Satellite
Fixed Wireless
Sprint
LAN
AOL
LAN
Dial-up
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The Evolution of the Enterprise
Late-1980s
Internal users
Private Corporate
Network
Dedicated facilities/
computer centers
Limited customer/
external access
Dedicated applications/
3rd party DBMS
E.g., Oracle
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The Evolution of the Enterprise
1995
Internal users
Private Corporate
Network
Dedicated facilities/
computer centers
Limited customer/
external access
Outsourced
“Enterprise Resource
Planning” Apps
e.g., PeopleSoft, BAAN
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The Evolution of the Enterprise
1997
Internal users
Virtual Private Network
ISP Mesh
Outsourced
Web Hosting
Internet
Dedicated Facility
Outsourced
ERP Apps
External Customers
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The Evolution of the Enterprise
1997
Internal users
P
o
r
t
a
l
Outsourced
Web Hosting
Search
Caching Internet
Ads
Services
EComm
Virtual Private Network
ISP
Mesh
Internet
Dedicated Facility
Outsourced
ERP Apps
External Customers
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The Evolution of the Enterprise
1999
3rd Party
Facilities Mgmt
P
o
r
t
a
l
Outsourced
Web Hosting
Search
Cache
Ads
EComm
Internet
Services
Applications
Service Provider
ISP Mesh
VPNs
Content Delivery “Net”
Caching +
Media Servers
Customers
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Services Within the Network:
Content Distribution
“Internet Grid”
Parallel Network Backbones
Internet Exchange Points
Co-Location
Scalable Servers
Web
Caches
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P2P Services in the Internet:
Napster, Gnutella, Freenet, …
Directory Service
Register my copy
Find me a copy
...
Madonna
Like a Virgin
Madonna
Material Girl
...
Look here
Grid computing: sharing resources/enabling collaboration
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Services Within the Network:
Streaming Media
Broadcasters
Content
Broadcast
Network
Content Distribution
Through Multicast
Overlay Network
Load Balancing Thru
Server Redirection;
Edge
Servers
Inter-ISP Redirection
Peering
Redirection
Fabric
Content
Broadcast
Management
Platform and
Tools
Clients
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Steve McCanne
Summary
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Course administrative trivia
Internet history and background
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