Transcript Overview of Computer Networks

CPET 355
Data Communications and
Networking
Paul I-Hai Lin, Professor
Electrical and Computer Engineering Technology
Purdue University, Fort Wayne Campus
Jan. 7, 2004
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Data Communication
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Data:
• Refers to: Information, Facts, Concepts,
Instructions
• Represented by: binary information
units (bits: 0, 1)
• Consists of: text, numbers, pictures,
sound, or video
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Data Communication
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(continue)
Data Communication
• Exchange of data between devices via
some form of transmission medium
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Data Communication
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(continue)
Three Fundamental
Characteristics
• How to Delivery: source, destination,
transmission signal, encoding, media,
interfacing, multiplexing
• Accuracy of Delivery: reliable and error
free
• Timeliness: efficient, real-time
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A Communication Model
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Message, Sender, Medium,
Receiver, and Protocol
Message
• Text, numbers, pictures, sound, video,
or a combination of these messages
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Sender
• Computer, workstation, server,
telephone handset, video camera, etc
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A Communications Model
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(continue)
Medium
• Twisted pair wire, coaxial cable, fiberoptic cable, laser, radio waves,
microwaves
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Receiver
• Computer, workstation, server, etc
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Protocol
• A set of rules that govern data
communications (HTTP, TCP/IP, PPP, etc
)
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Communications Tasks
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Message Formatting
Encryption, or Encoding
(Security)
Addressing
Routing
Synchronization
Flow Control
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Communications Tasks
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(continue)
Exchange Management
Error Detection and Correction
Recovery
Network Management
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Overview of Computer
Networks
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Introduction
Uses of Computer Networks
Network Hardware
Network Software
Reference Models and Standards
Example Networks
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Introduction
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Computer Network
• A collection of autonomous
computers interconnected by a
single technology
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Internet
• A network of networks
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World Wide Web
• A distributed system that runs on
the top of the Internet
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Introduction
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Distributed System
• A collection of independent
computers appears to its user as a
single coherent system
• A software system built on the top
of a network
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Middleware
• A software sit on the top of the OS
for implementing distribution
systems
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Definition of a Network
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A set of nodes (hosts) connected
by media links for resource
sharing, communications, etc
A Node: computer, server,
printer, etc
A Link: communication channel
Resources: printer, files,
programs, database, etc
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Networking
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Distributed Processing
• use network connected computers
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Loosely connected computer
networks
• LANs, WANs, WWW
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Uses of Computer Networks
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Business/Enterprise Applications
• E-Commerce, E-Business
• Manufacturing Applications
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Home Applications
Mobile Users
Educational Applications
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Business/Enterprise
Applications
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Resource Sharing
• Physical resources: printers, scanners, CD
burners, etc
• Information sharing (client-server
model): customer records, inventories,
account info, etc
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Communication and Information
Services
• email, videoconferencing, etc
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E-Commerce
E-Business
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Business/Enterprise
Applications (continue)
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Enterprise Resource Planning
Marketing, Sales, and Customer
Services
Supply Chain Management
Manufacturing (CAD/CAM),
robotics, industrial control,
measurement, monitoring
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Home Applications
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Access to remote information
Peer-to-peer communication
• Chat room, Instant messaging,
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Home appliances and security
Interactive entertainment
• Video games, video on demands,
Internet radio
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E-commerce
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Mobile Users
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Personal Digital Assistance (PDAs)
Global Positioning System (GPS)
Notebook Computers, Pocket PC,
Tablet PC
Cell phone
Mobile Wireless Networks – trucks,
taxis, delivery vehicles, etc
Utility meter reading
Military users
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Network Hardware
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Connection Technology
• Broadcast links
• Point-to-point links
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Scale
• Personal area networks
• Local area networks (wired, wireless)
• Metropolitan area networks (wired,
wireless)
• Wide area networks
• The Internet
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Network Criteria
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Performance
• No of users
• Types of transmission medium
• Hardware
• Software
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Reliability
Scalability
Security
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Local Area Networks
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Scale
• Room – 10m
• Building – 100m
• Campus – 1km
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Connection Technology
• Ethernet bus (wired, wireless)
• IBM Token ring
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Data rate:
• 10 Mbps, 100 Mbps, Giga bps
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Metropolitan Area Networks
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Scale
• City
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Connection Technology
• TV network
• Microwave, RF, antenna
• High-speed wireless IEEE 802.16
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Wide Area Networks
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Scale
• A country or continent
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Connection Technology
• Subnets
• Routers
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Transmission
• Store-and-forward or packet-switched
• Satellite systems
• Routing algorithm (shortest path, etc)
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Wireless Networks
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System interconnection
• Bluetooth – connecting digital
cameras, headsets, scanners, etc
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Wireless LANs (access point +
antenna)
• IEEE 802.11a
• IEEE 802.11b
• IEEE 802.11g
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Wireless WANs
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Home Networks
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Computers
Entertainment equipments
• TV/DVD, camcorder, camera, stereo, MP3
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Telecommunications
• telephone, mobile phone, intercom, fax
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Home appliances
• microwave, refrigerator, clock, furnace,
lights, heating and air conditioning
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Telemetry and Remote Monitoring
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Intrernetworks
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Gateway
• A computer with appropriate
software for connecting
incompatible networks
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Internetworks
• A network of distinct networks
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Network Software
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Protocols
Stacks of layers
Five-layer protocol
• TCP/IP protocol suite (FTP, TELNET,
http, etc)
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Seven-layer protocol: OSI (Open
Systems Interconnect) reference
model
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Network Software (continue)
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TCP/IP Five-Layer Protocol
• Application Layer - FTP, TELNET,
SMTP, DNS, HTTP, etc)
• Transport Layer – TCP, UDP
• Internet Layer – IP
• Data Link Layer
• Physical Layer
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Network Software (continue)
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OSI Seven-Layer Protocol
• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical
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Example Networks
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ARPANET
• ARPANET
• Advanced Research Project Agency NET
• A Small network started in the mid1960s for connecting mainframe
computers
• In 1969, four nodes are connected by
media links and IMP (interface message
processor); UCLA, UCSB, Stanford
Research Institute, and University of
Utah
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Example Networks (continue)
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TCP/IP-based Network
• 1973-1983
• Become official protocol for the
ARPANET
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MILNET: military users
ARPANET: non-military users
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Example Networks (continue)
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CSNET: networks for universities
and companies that connected
through TCP/IP, and Telnet;
sponsored by the National
Science Foundation, 1981-1986
NSFNET: a backbone that
connected 5 supercomputer
centers by a T1 (1.544 Mbps)
line; 1990 - 1995
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Example Networks (continue)
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Internet (Wide Area Networks)
• E-mail
• World wide web
• News
• Remote login
• File transfer
• Entertainment
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Example Networks (continue)
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Architecture of the Internet
• POP (point-of-presence)
• Regional ISP
• Backbone
• NAP (network access point)
• Routers
• Corporate LAN
• Server farm
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Example Networks (continue)
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Connection-Oriented Networks (WAN)
• X.25
 Public data network, deployed in
1970s
• Frame Relay
 Deployed in 1980s, replaced X.25
networks
• ATM (Asynchronous Transfer Mode)
 Designed in the early 1990s
 For solving telecomm and
networking problems
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Example Networks (continue)
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Ethernet (LAN)
• Designed and implemented at Xerox
Palo Alto Research Center, 1976
• Bob Metcalfe and David Boggs
• Xerox Ethernet failed to
commercialized
• Metcalfe formed 3Com to sell
Ethernet adapters
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Example Networks (continue)
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LAN Standards
• IEEE 802.3
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DIX standard by DEC, Intel, and Xerox,
1978, 10 Mbps Ethernet
DIX standard become IEEE 802.3 in
1983
• IEEE 802.4
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Token bus (GM)
• IEEE 802.5
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Token ring (IBM)
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Example Networks (continue)
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Wireless LAN Standards
• Design considerations
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Privacy, Security, Battery Life, Human
Safety
With a base station (access point)
Ad Hoc Networking (wireless peer
communicate with each other directly)
• IEEE 802.11
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Example Networks (continue)
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Wireless LAN Standards (1999-)
• IEEE 802.11a
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Up to 54 Mbps
• IEEE 802.11b
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Up to 11 Mbps
• IEEE 802.11g
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Up to 54 Mbps
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Example Networks (continue)
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Wireless LAN Standards (1999-)
• IEEE 802.15
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Bluetooth
10-meter distance
• IEEE 802.16
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Broadband Wireless WAN
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