msis4523 ch1.intro to datacom

8/3/2019 MSIS4523 Ch1.Intro to Datacom

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MSIS4523Data Communications SystemsCh.1 Data Communications & Networks

JinKyu Lee, Ph.D.

[email protected]


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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/


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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

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