ch01 13-12-2010

8/2/2019 ch01 13-12-2010

1/53

1.1

Welcome to

DATA COMMUNICATIONS

Prof. Farhat Anwar

ECE

Phone Ext: 4578

h/p: 0129076896

email: [email protected]

8/2/2019 ch01 13-12-2010

2/53

1.2

DATA COMMUNICATIONS

IntroductionReading Assignment: Chapter 1

Based on slides of Data Communications and Networking

by Behrouz A. Forouzan (4th ed), McGraw Hill, 2007

8/2/2019 ch01 13-12-2010

3/53

1.3

1-1 DATA COMMUNICATIONS1-1 DATA COMMUNICATIONS

Tele CommunicationsData

Data CommunicationsComputer Networks

Components

Data Representation

Data Flow

Topics discussed in this section:Top

ics discussed in this section:

8/2/2019 ch01 13-12-2010

4/53

1.4

Telecommunication/Data/Data communicationsTelecommunication/Data/Data communications

The termThe term telecommunicationtelecommunication means communication at ameans communication at a

distance.distance.

The wordThe worddatadata refers to information presented in whateverrefers to information presented in whatever

form is agreed upon by the parties creating and using theform is agreed upon by the parties creating and using the

data.data.

Data communicationsData communications are the exchange of data betweenare the exchange of data between

two devices via some form of transmission medium suchtwo devices via some form of transmission medium suchas a wire cable.as a wire cable.

8/2/2019 ch01 13-12-2010

5/53

1.5

1-1 DATA COMMUNICATIONS1-1 DATA COMMUNICATIONS

Definitions ofdata communications on the Web: The transmission of information between computers by means of a network such as an Ethernet,

a telephone system, or a satellite link.www.rcnp.osaka-u.ac.jp/unix/DOCUMENTATION/HTML/AA-QTM6A-TET1_html/reader5.html

transmission of data and information over a communications channel,www.jegsworks.com/Lessons/reference/glossary-d.htm

The electronic transmission of data, usually in computer readable form, using a variety oftransmission vehicles and paths.www.returncentral.com/Glossary.asp

(1) Transfer of information between a source and a destination via one or more data links,according to appropriate protocols. (2) Transmission and reception of data, often includingoperations such as coding, decoding and validation.www.itcom.itd.umich.edu/glossary.html

The transfer by electronic means of data from the point of origin to a computer, from computerto a user, or between two or more computers.www.disa.mil/cio/darmp/appadef.html

The transmission of data between computer systems using communication links such as phonelines or microwaves. Also involves the use of modems.www.encodasystems.com/resource_library/glossary/broadcast_glossary/d_glossary.htm

The reception, transmission & validation of data. The transfer of data between a data source &data link via one or more links.www.connectworld.net/iec/Browse02/GLSD.html
http://www.rcnp.osaka-u.ac.jp/unix/DOCUMENTATION/HTML/AA-QTM6A-TET1_html/reader5.htmlhttp://www.jegsworks.com/Lessons/reference/glossary-d.htmhttp://www.returncentral.com/Glossary.asphttp://www.itcom.itd.umich.edu/glossary.htmlhttp://www.disa.mil/cio/darmp/appadef.htmlhttp://www.encodasystems.com/resource_library/glossary/broadcast_glossary/d_glossary.htmhttp://www.connectworld.net/iec/Browse02/GLSD.htmlhttp://www.connectworld.net/iec/Browse02/GLSD.htmlhttp://www.encodasystems.com/resource_library/glossary/broadcast_glossary/d_glossary.htmhttp://www.disa.mil/cio/darmp/appadef.htmlhttp://www.itcom.itd.umich.edu/glossary.htmlhttp://www.returncentral.com/Glossary.asphttp://www.jegsworks.com/Lessons/reference/glossary-d.htmhttp://www.rcnp.osaka-u.ac.jp/unix/DOCUMENTATION/HTML/AA-QTM6A-TET1_html/reader5.html

8/2/2019 ch01 13-12-2010

6/53

1.6

1-1 DATA COMMUNICATIONS (cont.)1-1 DATA COMMUNICATIONS (cont.)

The movement of coded information by means of electronic transmission systems.www.utcg.com/glossary.htm

The transfer of informations from one location to another via electrical transmission systems.www.computersandinternet.com/Dictionary/Terms-D.htm

The transmission of data between a sender and a receiver. (See 131)highered.mcgraw-hill.com/sites/0072315326/student_view0/chapter4/glossary.html

A type of communications in which computers and terminals are able to exchange data over anelectronic medium.

www.novastars.com/modems.htm The transmission of data and information between two or more computers using a

communications channel such as a standard telephone line; also called communications, ortelecommunications. 1.8, 6.2-35www.scsite.com/dc/main_glossary_d.htm

The interchange of data messages from one point to another over communications circuits.homepages.bw.edu/~kweiss/glossary/d.html

The capacity of a computer to exchange information with another computer.www.geos-infobase.de/ND_DOCS/268.HTM

The transmission or sharing of data between computers via an electronic medium.www.brivers.com/ua/modems/other/usr_analog_glossary.htm
http://www.utcg.com/glossary.htmhttp://www.computersandinternet.com/Dictionary/Terms-D.htmhttp://highered.mcgraw-hill.com/sites/0072315326/student_view0/chapter4/glossary.htmlhttp://www.novastars.com/modems.htmhttp://www.scsite.com/dc/main_glossary_d.htmhttp://homepages.bw.edu/~kweiss/glossary/d.htmlhttp://www.geos-infobase.de/ND_DOCS/268.HTMhttp://www.brivers.com/ua/modems/other/usr_analog_glossary.htmhttp://www.brivers.com/ua/modems/other/usr_analog_glossary.htmhttp://www.geos-infobase.de/ND_DOCS/268.HTMhttp://homepages.bw.edu/~kweiss/glossary/d.htmlhttp://www.scsite.com/dc/main_glossary_d.htmhttp://www.novastars.com/modems.htmhttp://highered.mcgraw-hill.com/sites/0072315326/student_view0/chapter4/glossary.htmlhttp://www.computersandinternet.com/Dictionary/Terms-D.htmhttp://www.utcg.com/glossary.htm

8/2/2019 ch01 13-12-2010

7/531.7

Effectiveness of Data Communications SystemEffectiveness of Data Communications System

Depends on three fundamental characteristics:

Delivery

Accuracy

Timeliness

Jitter

8/2/2019 ch01 13-12-2010

8/531.8

Data CommunicationsData Communications

Topics discussed in this section:Topics discussed in this section:

Components

Data Representation Data Flow

8/2/2019 ch01 13-12-2010

9/531.9

Figure 1.1 Five components of data communication

1

2 34

5

8/2/2019 ch01 13-12-2010

10/531.10



Components Data Representation Data Flow

8/2/2019 ch01 13-12-2010

11/531.11

Data RepresentationData Representation

Information comes in different forms:Information comes in different forms:

TextTextNumbersNumbers

ImagesImagesAudioAudioVideoVideo

Etcetera, Etcetera, EtceteraEtcetera, Etcetera, Etcetera

8/2/2019 ch01 13-12-2010

12/531.12



Components

Data Representation Data Flow

8/2/2019 ch01 13-12-2010

13/531.13

Figure 1.2 Data flow (simplex, half-duplex, and full-duplex)

8/2/2019 ch01 13-12-2010

14/531.14

1-2 NETWORKS1-2 NETWORKS

AA

networknetwork

is a set of devices (often referred to asis a set of devices (often referred to as

nodesnodes

))

connected by communicationconnected by communication linkslinks. A node can be a. A node can be a

computer, printer, or any other device capable of sendingcomputer, printer, or any other device capable of sending

and/or receiving data generated by other nodes on theand/or receiving data generated by other nodes on the

network.network.

8/2/2019 ch01 13-12-2010

15/531.15

Computer NetworkComputer Network

Definitions ofComputer network on the Web: A set of computers that are connected and able to exchange data.

www.ciao.gov/ciao_document_library/glossary/C.htm A computer network is two or more computers that are connected together to share resources,

such as hardware, data, and/or software. A network that covers a small geographical area, suchas a room or a building, is called a local area network or LAN. See LANwww.menominee.nsn.us/MIS/Pages/MISGlossary.htm

a group of computers that are connected by cables or telephone lines that share the sameresources such as databaseslibrary.kcc.hawaii.edu/external/hookele/susan/glossary.html

A data communication system that interconnects computer systems at different sites. DukeNet isthe Duke University computer network. The Common Services Network (CSN) is Duke HealthSystems computer network.www.aas.duke.edu/comp/security/definitions.html

Two or more computers connected together to share resources.www.marketconscious.com/dict.htm

A computer network can be defined as: a communications system that links two or morecomputers and peripheral devices and enables transfer of data between the components.wps.prenhall.com/wps/media/objects/505/517554/glossary.html

A hardware mechanism that computers use to communicate. A network is classified as a LocalArea Network or Wide Area Network, depending on the hardware capabilities.www.dca.fee.unicamp.br/~antonio/glossary.html

Interconnection of two or more CPUs with associated memories, peripheral devices, etc.www.computersandinternet.com/Dictionary/Terms-C.htm
http://www.ciao.gov/ciao_document_library/glossary/C.htmhttp://www.menominee.nsn.us/MIS/Pages/MISGlossary.htmhttp://library.kcc.hawaii.edu/external/hookele/susan/glossary.htmlhttp://www.aas.duke.edu/comp/security/definitions.htmlhttp://www.marketconscious.com/dict.htmhttp://wps.prenhall.com/wps/media/objects/505/517554/glossary.htmlhttp://www.dca.fee.unicamp.br/~antonio/glossary.htmlhttp://www.computersandinternet.com/Dictionary/Terms-C.htmhttp://www.computersandinternet.com/Dictionary/Terms-C.htmhttp://www.dca.fee.unicamp.br/~antonio/glossary.htmlhttp://wps.prenhall.com/wps/media/objects/505/517554/glossary.htmlhttp://www.marketconscious.com/dict.htmhttp://www.aas.duke.edu/comp/security/definitions.htmlhttp://library.kcc.hawaii.edu/external/hookele/susan/glossary.htmlhttp://www.menominee.nsn.us/MIS/Pages/MISGlossary.htmhttp://www.ciao.gov/ciao_document_library/glossary/C.htm

8/2/2019 ch01 13-12-2010

16/531.16

Computer Network (cont.)Computer Network (cont.)

A collection of computers and other devices that use a common network protocol to shareresources with each other over a network medium.www.cse.iitb.ac.in/~paraga/books/1555582141/glossary.html

is two or more computers connected so that they can communicate with each other and shareinformation, software, peripheral devices, and/or processing power.highered.mcgraw-hill.com/sites/0072464011/student_view0/chapter6/glossary.html

Communications system connecting two or more computers and their peripheral devices.www.mhhe.com/it/oleary/ce01-02/student/olc/glo_ch09.mhtml

A collection of computers, connected by wires, that can exchange data with each other.www.ncu.edu.jm/infosci/courses/cptr250/glossary.htm An interconnection of computer systems, terminals, communications facilities, and data collecting

devices.homepages.bw.edu/~kweiss/glossary/c.html

(computer science) a network of computerswww.cogsci.princeton.edu/cgi-bin/webwn
http://www.cse.iitb.ac.in/~paraga/books/1555582141/glossary.htmlhttp://highered.mcgraw-hill.com/sites/0072464011/student_view0/chapter6/glossary.htmlhttp://www.mhhe.com/it/oleary/ce01-02/student/olc/glo_ch09.mhtmlhttp://www.ncu.edu.jm/infosci/courses/cptr250/glossary.htmhttp://homepages.bw.edu/~kweiss/glossary/c.htmlhttp://www.cogsci.princeton.edu/cgi-bin/webwn?stage=1&word=computer+networkhttp://www.cogsci.princeton.edu/cgi-bin/webwn?stage=1&word=computer+networkhttp://homepages.bw.edu/~kweiss/glossary/c.htmlhttp://www.ncu.edu.jm/infosci/courses/cptr250/glossary.htmhttp://www.mhhe.com/it/oleary/ce01-02/student/olc/glo_ch09.mhtmlhttp://highered.mcgraw-hill.com/sites/0072464011/student_view0/chapter6/glossary.htmlhttp://www.cse.iitb.ac.in/~paraga/books/1555582141/glossary.html

8/2/2019 ch01 13-12-2010

17/531.17



Distributed ProcessingNetwork CriteriaPhysical Structures

Network Models

Categories of Networks

Interconnection of Networks:Internetwork

8/2/2019 ch01 13-12-2010

18/531.18



Distributed Processing

Network CriteriaPhysical Structures

Network Models



8/2/2019 ch01 13-12-2010

19/531.19


Network Criteria

Performance Measured transit time, response time etc.

Factors no. of users, transmission medium type, hardwarecapabilities, software efficiency etc.

Reliability Measured frequency of failure, recovery time etc.

Security

8/2/2019 ch01 13-12-2010

20/53

1.20




Network CriteriaPhysical StructuresNetwork Models



8/2/2019 ch01 13-12-2010

21/53

1.21


Physical Structures (attributes)

Type of connection Point-to-point

Multipoint or multidrop

Physical topology Mesh

Star Bus Ring

8/2/2019 ch01 13-12-2010

22/53

1.22

Figure 1.3 Types of connections: point-to-point and multipoint

8/2/2019 ch01 13-12-2010

23/53

1.23


Physical topology

The topology of a network is the geometric representation of therelationship of all the links and linking devices (nodes) to one

another

8/2/2019 ch01 13-12-2010

24/53

1.24

Figure 1.4 Categories of topology

8/2/2019 ch01 13-12-2010

25/53

1.25

Figure 1.5 A fully connected mesh topology (five devices)

No of channels or links = n(n-1)/2

No of links/node = n-1

No of I/O ports/node = n-1

8/2/2019 ch01 13-12-2010

26/53

1.26

Figure 1.6 A star topology connecting four stations

No of channels or links = n

No of links/node = 1

No of I/O ports/node = 1

8/2/2019 ch01 13-12-2010

27/53

1.27

Figure 1.7 A bus topology connecting three stations

Backbone

8/2/2019 ch01 13-12-2010

28/53

1.28

Figure 1.8 A ring topology connecting six stations

8/2/2019 ch01 13-12-2010

29/53

1.29

Figure 1.9 A hybrid topology: a star backbone with three bus networks

8/2/2019 ch01 13-12-2010

30/53

1.30





Network ModelsCategories of Networks


8/2/2019 ch01 13-12-2010

31/53

1.31


Network Models Computer networks are created by different entities.

Standards are needed for heterogeneous networks to beable to communicate with each other.

Two best known standards include, OSI (Open Systems Interconnection), 7 layers Internet model (TCP/IP) 5 layers

8/2/2019 ch01 13-12-2010

32/53

1.32





Network Models

Categories of NetworksInterconnection of Networks:Internetwork

8/2/2019 ch01 13-12-2010

33/53

1.33


Categories

LAN MAN

WAN

Determined by its size, ownership, distance covered, physicalarchitecture

8/2/2019 ch01 13-12-2010

34/53

1.34


Categories

8/2/2019 ch01 13-12-2010

35/53

1.35

Figure 1.10 An isolated LAN connecting 12 computers to a hub in a closet

8/2/2019 ch01 13-12-2010

36/53

1.36

Figure 1.11 WANs: a switched WAN and a point-to-point WAN

8/2/2019 ch01 13-12-2010

37/53

1.37





Network Models



8/2/2019 ch01 13-12-2010

38/53

1.38

Figure 1.12 A heterogeneous network made of four WANs and two LANs

8/2/2019 ch01 13-12-2010

39/53

1.39





Network Models



8/2/2019 ch01 13-12-2010

40/53

1.40

1-3 THE INTERNET1-3 THE INTERNET

TheThe InternetInternethas revolutionized many aspects of our dailyhas revolutionized many aspects of our dailylives. It has affected the way we do business as well as thelives. It has affected the way we do business as well as the

way we spend our leisure time. The Internet is away we spend our leisure time. The Internet is a

communication system that has brought a wealth ofcommunication system that has brought a wealth of

information to our fingertips and organized it for our use.information to our fingertips and organized it for our use.

A Brief History

The Internet Today (ISPs)


8/2/2019 ch01 13-12-2010

41/53

1.41

Internet History Timeline

1957:The United States Department of Defense formed a small agency called ARPA (Advanced1957:The United States Department of Defense formed a small agency called ARPA (Advanced

Research Projects Agency) to develop military science and technology.Research Projects Agency) to develop military science and technology.

1961-1965:The Massachusetts Institute of Technology (MIT) started to research sharing information1961-1965:The Massachusetts Institute of Technology (MIT) started to research sharing information

in small, phone-linked networks. ARPA is one of their main sponsors.in small, phone-linked networks. ARPA is one of their main sponsors.

1966: The first ARPANET plan is unveiled by Larry Roberts of MIT. Packet switching technology is1966: The first ARPANET plan is unveiled by Larry Roberts of MIT. Packet switching technology is

getting off the ground, and small university networks are beginning to be developed.getting off the ground, and small university networks are beginning to be developed.

1969:The Department of Defense commissions the fledgling ARPAnet for network research. The first1969:The Department of Defense commissions the fledgling ARPAnet for network research. The first

official network nodes were UCLA, Standford Research Institute,UCSB, and the University of Utah. Theofficial network nodes were UCLA, Standford Research Institute,UCSB, and the University of Utah. The

first node to node message was sent from UCLA to SRI.first node to node message was sent from UCLA to SRI.

1971: more nodes join the network, bringing the total to 15. These new nodes include Harvard and1971: more nodes join the network, bringing the total to 15. These new nodes include Harvard and

NASA.NASA.

1973: ARPAnet goes global when the the University College of London and Norway's Royal Radar1973: ARPAnet goes global when the the University College of London and Norway's Royal Radar

Establishment join up.Establishment join up.

1974: Network intercommunication is becoming more sophisticated; data is now transmitted more1974: Network intercommunication is becoming more sophisticated; data is now transmitted more

quickly and efficiently with the design of TCP (Transmission Control Program).quickly and efficiently with the design of TCP (Transmission Control Program).

8/2/2019 ch01 13-12-2010

42/53

1.42

Internet History Timeline (cont.)

1976: Unix is developed at AT and T; Queen Elizabeth sends out her first email message.1976: Unix is developed at AT and T; Queen Elizabeth sends out her first email message.

1979: USENET, the mother of all networked discussion groups, is developed.1979: USENET, the mother of all networked discussion groups, is developed.

1982: Internet technology protocols are developed, commonly known as TCP/IP (Transmission1982: Internet technology protocols are developed, commonly known as TCP/IP (Transmission

Control Protocol and Internet Protocol). This leads to one of the first definitions of an "internet" beingControl Protocol and Internet Protocol). This leads to one of the first definitions of an "internet" being

a connected set of networks.a connected set of networks.

1984: Number of hosts is now up to 1000, with more being added every day.1984: Number of hosts is now up to 1000, with more being added every day.

1985: The first registered domain is Symbolics.com.1985: The first registered domain is Symbolics.com.

1987: Number of hosts breaks the 10,000 mark.1987: Number of hosts breaks the 10,000 mark.

1988: First large-scale Internet worm affects thousands of Internet hosts.1988: First large-scale Internet worm affects thousands of Internet hosts.

1991: Tim Berners-Lee develops the World Wide Web.1991: Tim Berners-Lee develops the World Wide Web.

1993: The World Wide Web's annual growth is now at a staggering 341,634%.1993: The World Wide Web's annual growth is now at a staggering 341,634%.

8/2/2019 ch01 13-12-2010

43/53

1.43

Internet History Timeline (cont.)

1994: ARPAnet celebrates 25th anniversary.1994: ARPAnet celebrates 25th anniversary.

1995-1997: RealAudio introduces Internet streaming technology, dial-up systems emerge (America1995-1997: RealAudio introduces Internet streaming technology, dial-up systems emerge (America

Online, Compuserve), the Internet backbone continues to be strengthened with the addition of MCI,Online, Compuserve), the Internet backbone continues to be strengthened with the addition of MCI,

Microsoft and Netscape fight for WWW browser supremacy, and there are now more than 70,000Microsoft and Netscape fight for WWW browser supremacy, and there are now more than 70,000

mailing lists.mailing lists.

1998-present:The Internet continues to experience staggering growth. More people use the Internet to1998-present:The Internet continues to experience staggering growth. More people use the Internet to

get connected to others, find information, conduct business, and share information than ever before inget connected to others, find information, conduct business, and share information than ever before in

history.history.

Ref - http://websearch.about.com/od/whatistheinternet/a/historyinternet.htmRef - http://websearch.about.com/od/whatistheinternet/a/historyinternet.htm

8/2/2019 ch01 13-12-2010

44/53

1.44

Internet Growth Charts

Ref - http://navigators.com/stats.htmlRef - http://navigators.com/stats.html

8/2/2019 ch01 13-12-2010

45/53

1.45

Figure 1.13 Hierarchical organization of the Internet

8/2/2019 ch01 13-12-2010

46/53

1.46

Hierarchical organization of the Internet

Internet service providers

Network access points

1 4 PROTOCOLS AND STANDARDS1 4 PROTOCOLS AND STANDARDS

8/2/2019 ch01 13-12-2010

47/53

1.47

1-4 PROTOCOLS AND STANDARDS1-4 PROTOCOLS AND STANDARDS

In this section, we define two widely used terms:In this section, we define two widely used terms: protocolsprotocolsandand standardsstandards. First, we define protocol, which is. First, we define protocol, which is

synonymous with rule. Then we discuss standards, whichsynonymous with rule. Then we discuss standards, which

are agreed-upon rules.are agreed-upon rules.

ProtocolsStandards

Standards Organizations

Internet Standards


PROTOCOLSPROTOCOLS

8/2/2019 ch01 13-12-2010

48/53

1.48

PROTOCOLSPROTOCOLS

A protocol is a set of rules that governs the datacommunications

Key Elements:

Syntax : Structure or format Semantics : Meaning of each section of bits Timing : When data should be sent and

how fast data can be sent

STANDARDSSTANDARDS

8/2/2019 ch01 13-12-2010

49/53

1.49

STANDARDSSTANDARDS

Standards are essential in creating and maintaining an open and competitive market for

equipment manufacturers and in guaranteeing national and international interoperability of

data and telecommunications technology and processes.

Categories : De facto De jure

STANDARDSSTANDARDS

8/2/2019 ch01 13-12-2010

50/53

1.50

STANDARDSSTANDARDS

De facto (Latin expression that means "of the fact" or "in practice)That have not been approved by an organized body but havebeen adapted as standards through widespread use.

Some examples of de facto standards include: Hayes command set for controlling modems Kermit Communications Protocol Xmodem Communications Protocol Hewlett-Packard Printer Control Language (PCL) for laser printers. PostScript page description language for laser printers

The IBM PC format which used MS-DOS and MS Windowsoperating systems Portable Document Format (PDF), first published in 1993 by Adobe. AutoCAD

STANDARDSSTANDARDS

8/2/2019 ch01 13-12-2010

51/53

1.51

STANDARDSSTANDARDS

De jure ("by law")That have been legislated by an officially recognized body,Hardware or software that is endorsed by a standardsorganization.

Some examples of de facto standards include: Hayes command set for controlling modems

STANDARDS ORGANIZATIONSSTANDARDS ORGANIZATIONS

8/2/2019 ch01 13-12-2010

52/53

1.52

STANDARDS ORGANIZATIONSSTANDARDS ORGANIZATIONS

International organization for standardization (ISO) International Telecommunication Union Telecommunication

Standards Sector (ITU-T)Previously called CCITT (Comit Consultatif International deTlgraphique et Tlphonique or International Telegraph andTelephone Consultative Committee)

American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) Electronic Industries Association (EIA)

INTERNET STANDARDSINTERNET STANDARDS

8/2/2019 ch01 13-12-2010

53/53

INTERNET STANDARDSINTERNET STANDARDS

Requests for comments

UDP RFC 768TCP RFC 793, 1122, 1323, 2018 and 2581

IP RFC 791 (IPv4), RFC 2373, 2460 (IPv6)

ch01 13-12-2010

Documents