Post on 07-Apr-2018
transcript
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MSIS4523Data Communications SystemsCh.1 Data Communications & Networks
JinKyu Lee, Ph.D.
Jinkyu.lee@okstate.edu
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Topics
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Telecommunication & Data Communication Components of Data Communication
Direction of Data Flow
Link vs. Network
Network Topology
Categories of Networks
Protocols and Standards
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What Is Communication?
Symbolic Dependent upon the medium (language)
Arbitrary mapping should be interpreted
Representational The map is not the territory.
Communication is only as good as the representation
Examples
Verbal language, gestures, actions, icons
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Human Communication vs. DataCommunication
Human communication is richer, less predictable Words vary in meaning with context
Many factors influence meaning and perception ofmessage
Data communication is more precise
Exact replication of information
Computers do not interpret, they simply relay
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Definitions
Telecommunications - The transmission ofinformation between or among pointsspecified by the user
Data Communications - The movement ofcomputerinformation from one point toanother by means of electrical or opticaltransmission systems
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Five components of data communication Systems
Sender
Receiver
Message
TransmissionMedium
Protocol
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Directions of Communications:Simplex Data Flows
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Directions of CommunicationsHalf Duplex Data Flows
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Directions of Communications:Full Duplex Data Flows
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Access to Link: Point-to-Point Connection
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Access to Link: Multipoint Connection
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Network Topology:Fully Connected Mesh Topology
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Network Topology: Star topology
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Network Topology: Bus topology
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Network Topology: Ring topology
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The Key Network Types
LAN - Local Area Network
Single building or cluster of buildings
Ethernet, token ring, star
MAN Metropolitan Area Network
Multiple disjoint locations in one city
WAN - Wide Area Network
City-to-city, country-to-country
Telephone, ATM, SONET, etc.
Wireless Network
Radio, microwave, satellite, cellular, infrared
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Local Area Networks (LAN)
A group of microcomputers or other workstationdevices located in the same general area andconnected by a common circuit
Covers a clearly defined small area, such as
within or between a few buildings Support data rates of 10 Mbps to 10 Gbps
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Campus LAN
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Metropolitan Area Network (MAN)
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Wide Area Networks (WAN)
Large geographical area
Rely in part on common carrier circuits
Alternative technologies
Circuit switching
Packet switching
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The Internet !!What is this? A horoscope?
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Internet today
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US Backbone Networks & Peering Points
The North American backbone
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The North American backbone
(Mar. 2006, cio.com)
134,855 Routers on theNorth American
backbone.
Red : VerizonBlue: AT&TYellow: QwestGreen: Major backboneplayers (e.g., Level 3 andSprint Nextel)
Black: Cable industryGray: everyone else
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What is a Communication Protocol?
Shared rules for communicating informationbetween entities on two or more systems
Three Elements
Syntax : data format and signal levels
Semantics : interpretation and handling of data Timing : speed matching and sequencing
Who need to know?
Many Possible Entities
User applications, e-mail facilities, terminals
Many Types of Systems
Computer, Terminal, Remote sensor
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Telecommunication Standards Org.
International Telecommunications Union -Telecommunication Standardization Sector (ITU-TSS) Formerly called the Consultative Committee on
International Telegraph and Telephone (CCITT) International Organization for Standards (ISO)
Member of the ITU, makes technicalrecommendations about data communications
interfaces Internet Engineering Task Force (IETF)
* Standards = Protocols??
http://info.internet.isi.edu/in-notes/rfc/files/http://info.internet.isi.edu/in-notes/rfc/files/8/3/2019 MSIS4523 Ch1.Intro to Datacom
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Telecommunication Standards Org's Cont
Institute of Electrical and Electronics Engineers(IEEE)
Electronic Industries Association (EIA)
National Institute of Standards and Technology
(NIST) National Exchange Carriers Association (NECA)
Corporation for Open Systems (COS)
ATM forum, OIF, W3C, many others
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Internet Standards
Email related standards
IMAP, POP, X.400, SMTP, MIME, binhex, uuencode
Web related standards
http, CGI, html/xml/vrml/sgml
Internet directory standards X.500, LDAP
Application standards
http, FTP, telnet, gopher, wais Videoconferencing standards
H.320, H.323, Mpeg-1, Mpeg-2
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Telecommunications Standards
Modems
V.32, V.90, V.92
Voice Circuit Switched
A-Law, -Law
Voice Packetized H.323
Call Control Signaling
SS7, Q.932, GR-303, GR-317, GR-394
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Maturity levels of an RFC
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RFC Requirement Levels
http://www rfc editor org