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Chapter 1 
Introduction 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Chapter 1 
At the end of the 
discussion, students will be 
able to identify the 
fundamental 
characteristics of a data 
...
NNoottee:: 
Data communications and networking 
is changing we do business and the 
way we live. 
McGraw-Hill ©The McGraw-...
1.1 Data Communication 
Components 
Data Representation 
Direction of Data Flow 
McGraw-Hill ©The McGraw-Hill Companies, I...
NNoottee:: 
TELECOMMUNICATION 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.1 Simple Network Diagram 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Data communication fundamental characteristics 
 Delivery 
 System must deliver the data to the correct 
destination 
 ...
Five components of data communication 
 Message 
 Information (data) to be communicated. 
 Sender 
 Device that sends ...
Figure 1.1 Five components of communication 
system 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
NNoottee:: 
Information today comes in different 
forms. 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Data Representation 
 Text 
 Represented as a bit pattern 
 Numbers 
 Also represented as a bit pattern 
 Images 
 C...
NNoottee:: 
Communication between two devices 
can be either simplex, half-duplex and 
duplex. 
McGraw-Hill ©The McGraw-Hi...
Simplex 
In simplex mode, the communication is unidirectional . 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Half-duplex 
In half-duplex mode, each station can both transmit 
and receive, but not at the same time. 
McGraw-Hill ©The...
Full-duplex 
In full-duplex mode both stations can transmit and 
receive simultaneously 
McGraw-Hill ©The McGraw-Hill Comp...
1.2 Networks 
Distributed Processing 
Network Criteria 
Physical Structures 
Categories of Networks 
McGraw-Hill ©The McGr...
NNoottee:: 
A network is a set of devices (called as 
nodes) connected by communication 
links. 
McGraw-Hill ©The McGraw-H...
NNoottee:: 
Distributed processing is the division 
of tasks in a network among its 
computers. 
McGraw-Hill ©The McGraw-H...
NNoottee:: 
A network must meet a certain number 
of criteria: performance, reliability 
and security. 
McGraw-Hill ©The M...
Network Criteria 
 Performance 
 Depends on a number of factors, including 
transit time, response time, number of users...
NNoottee:: 
A network is two or more devices 
connected through links. 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Types of Connection 
 Point-to Point (P2P) 
 Provides a dedicated link between two 
devices. 
McGraw-Hill ©The McGraw-Hi...
Types of Connection 
 Multipoint (P2MP) 
 More than two specific devices share a single 
link. 
 Also called multidrop/...
NNoottee:: 
Physical topology refers to the way in 
which a network is laid out physically. 
McGraw-Hill ©The McGraw-Hill ...
Basic Topologies 
 Mesh topology 
 Every device has a dedicated point-to-point 
link to every other device. 
McGraw-Hill...
EExxaammppllee 
Consider a mesh network with 6 nodes, calculate how 
many cable connections needed in order to have a 
com...
Basic Topologies 
 Mesh topology 
 Advantage: 
 Dedicated links guarantees own data load 
 Robust 
 Privacy/Security ...
Basic Topologies 
 Star topology 
 Each device has a dedicated point-to-point 
link only to a central controller, usuall...
Basic Topologies 
 Bus topology 
 One long cable acts as a backbone to link all the 
devices in a network 
McGraw-Hill ©...
Basic Topologies 
 Ring topology 
 Each device has a dedicated point-to-point 
connection with only the two devices on e...
Basic Topologies 
 Ring topology 
 Advantage: 
 Orderly 
 Performs better than bus topology 
 Does not require networ...
Basic Topologies 
 Hybrid (Tree) topology 
 The topology in which a central 'root' node is 
connected to one or more oth...
Basic Topologies 
 Star topology 
 Advantage: 
 Easy to install and reconfigure 
 Less cabling needed 
 Robust 
 Sim...
Basic Topologies 
 Hybrid (Tree) topology 
 Advantage: 
 Supported by hardware vendors 
 P2P connection is possible 
...
Basic Topologies 
 Bus topology 
 Advantage: 
 Easy to implement and extend 
 Easy to install 
 Cost effective 
 Sim...
Chapter 1 
1. What is the difference between audio to 
text, numbers and images? 2pts 
2. What are the 3 characteristics o...
NNoottee:: 
The category into which a network 
falls is determined by its size. 
McGraw-Hill ©The McGraw-Hill Companies, I...
Categories of Networks 
 Local Area Network (LAN) 
 connects nodes in a limited geographical area 
 normally covers an ...
Categories of Networks 
 Metropolitan Area Network (MAN) 
 larger than a LAN but smaller than a WAN 
 normally covers a...
Categories of Networks 
 Wide Area Network (MAN) 
 spans a large physical distance 
 Internet is the largest WAN 
 is ...
Categories of Networks 
 Heterogeneous Network 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
NNoottee:: 
Interconnection of Networks: 
Internetwork 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Internet 
 History 
 1960’s US government seeks nuclear war proof 
communications, created ARPA 
 1969 Universities and...
NNoottee:: 
A protocol is a set of guidelines or rules. 
A technical standard is an established 
norm or requirement. 
McG...
Protocols and Standards 
 Protocols 
 rules determining the format and transmission 
of data 
 key elements of a protoc...
Protocols and Standards 
 Standards 
 provide guidelines to create and maintain an open 
competitive market 
 categorie...
Protocols and Standards 
 Standards 
 Forums 
 made up of representatives from interested corporations 
 test, evaluat...
NNoottee:: 
End of Chapter 1 
McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Chapter Questions: 
Q.1) Which of the following are types of computer networks? 
A. LAN, NAN, WAN 
B. WAN, ring, star, bus...
Chapter Questions: 
1. Identify the five properties of a data 
communications system. 
2. Name four basic network topologi...
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Data com chapter 1 introduction

  1. 1. Chapter 1 Introduction McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  2. 2. Chapter 1 At the end of the discussion, students will be able to identify the fundamental characteristics of a data communication system. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  3. 3. NNoottee:: Data communications and networking is changing we do business and the way we live. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  4. 4. 1.1 Data Communication Components Data Representation Direction of Data Flow McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  5. 5. NNoottee:: TELECOMMUNICATION McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  6. 6. Figure 1.1 Simple Network Diagram McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  7. 7. Data communication fundamental characteristics  Delivery  System must deliver the data to the correct destination  Accuracy  System must deliver the data accurately  Timeliness  System must deliver the data in timely manner  Jitter  Variation in the packet arrival time. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  8. 8. Five components of data communication  Message  Information (data) to be communicated.  Sender  Device that sends the data message.  Transmission Medium  Carries data.  Receiver  Device that receives the message.  Protocol  Set of rules that govern data communication. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  9. 9. Figure 1.1 Five components of communication system McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  10. 10. NNoottee:: Information today comes in different forms. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  11. 11. Data Representation  Text  Represented as a bit pattern  Numbers  Also represented as a bit pattern  Images  Composed of a matrix of pixels  Audio  Recording or broadcasting of sound or music  Video  Recording or broadcasting of picture or movie McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  12. 12. NNoottee:: Communication between two devices can be either simplex, half-duplex and duplex. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  13. 13. Simplex In simplex mode, the communication is unidirectional . McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  14. 14. Half-duplex In half-duplex mode, each station can both transmit and receive, but not at the same time. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  15. 15. Full-duplex In full-duplex mode both stations can transmit and receive simultaneously McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  16. 16. 1.2 Networks Distributed Processing Network Criteria Physical Structures Categories of Networks McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  17. 17. NNoottee:: A network is a set of devices (called as nodes) connected by communication links. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  18. 18. NNoottee:: Distributed processing is the division of tasks in a network among its computers. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  19. 19. NNoottee:: A network must meet a certain number of criteria: performance, reliability and security. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  20. 20. Network Criteria  Performance  Depends on a number of factors, including transit time, response time, number of users, type of transmission medium, throughput and delay.  Reliability  Measured by the frequency of failure, the time it takes a link to recover and the network’s robustness in catastrophe.  Security  Includes protecting data from unauthorized access, protecting data from damage and development, etc. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  21. 21. NNoottee:: A network is two or more devices connected through links. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  22. 22. Types of Connection  Point-to Point (P2P)  Provides a dedicated link between two devices. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  23. 23. Types of Connection  Multipoint (P2MP)  More than two specific devices share a single link.  Also called multidrop/broadcast connection. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  24. 24. NNoottee:: Physical topology refers to the way in which a network is laid out physically. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  25. 25. Basic Topologies  Mesh topology  Every device has a dedicated point-to-point link to every other device. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  26. 26. EExxaammppllee Consider a mesh network with 6 nodes, calculate how many cable connections needed in order to have a complete mesh configuration? ## ooff lliinnkkss == 66 ((66 -- 11)) // 22 == 1155 lliinnkkss McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  27. 27. Basic Topologies  Mesh topology  Advantage:  Dedicated links guarantees own data load  Robust  Privacy/Security  Easy fault isolation  Disadvantage  Amount of cabling and no. of I/O ports required  Difficult installation and reconnection  Expensive McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  28. 28. Basic Topologies  Star topology  Each device has a dedicated point-to-point link only to a central controller, usually called a HUB. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  29. 29. Basic Topologies  Bus topology  One long cable acts as a backbone to link all the devices in a network McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  30. 30. Basic Topologies  Ring topology  Each device has a dedicated point-to-point connection with only the two devices on either side of it. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  31. 31. Basic Topologies  Ring topology  Advantage:  Orderly  Performs better than bus topology  Does not require network server  Disadvantage  Failure of a single node, failure of entire network  Sensitive to node changes McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  32. 32. Basic Topologies  Hybrid (Tree) topology  The topology in which a central 'root' node is connected to one or more other nodes that are one level lower in the hierarchy. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  33. 33. Basic Topologies  Star topology  Advantage:  Easy to install and reconfigure  Less cabling needed  Robust  Simplicity of operation  Disadvantage  Dependency on one single point  Possible slow down of network McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  34. 34. Basic Topologies  Hybrid (Tree) topology  Advantage:  Supported by hardware vendors  P2P connection is possible  Ease of node access  Disadvantage  Length of network depends of the type of cable  Entirely dependent on the trunk  Difficult to configure McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  35. 35. Basic Topologies  Bus topology  Advantage:  Easy to implement and extend  Easy to install  Cost effective  Simplicity of operation  Disadvantage  Difficult reconnection and fault isolation  Dependency on the bus  Limited cable length and number of stations McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  36. 36. Chapter 1 1. What is the difference between audio to text, numbers and images? 2pts 2. What are the 3 characteristics of a network? 3. Consider a mesh network with 7 nodes, calculate how many cable connections needed in order to have a complete mesh configuration? McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  37. 37. NNoottee:: The category into which a network falls is determined by its size. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  38. 38. Categories of Networks  Local Area Network (LAN)  connects nodes in a limited geographical area  normally covers an area less than 2 mi.  e.g. home, school, computer lab, office bldg.  uses Ethernet cables, switches and hubs McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  39. 39. Categories of Networks  Metropolitan Area Network (MAN)  larger than a LAN but smaller than a WAN  normally covers a town or a city  connects nodes for high-speed connectivity  e.g. DSL internet connection, cable internet connection McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  40. 40. Categories of Networks  Wide Area Network (MAN)  spans a large physical distance  Internet is the largest WAN  is not owned by any one organization  use technology like ATM, Frame Relay and X.25 McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  41. 41. Categories of Networks  Heterogeneous Network McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  42. 42. NNoottee:: Interconnection of Networks: Internetwork McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  43. 43. Internet  History  1960’s US government seeks nuclear war proof communications, created ARPA  1969 Universities and researches connected to ARPAnet  In 1972, Vinton Cerf and Robert Kahn collaborated for the Internetting Project  In 1977 ARPAnet engineers devised a communication protocol known as TCP/IP  1983 ARPAnet switched to TCP/IP  1989 Tim Berners-Lee proposes a new set of Internet protocols  1995 US government releases Internet for commercial use McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  44. 44. NNoottee:: A protocol is a set of guidelines or rules. A technical standard is an established norm or requirement. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  45. 45. Protocols and Standards  Protocols  rules determining the format and transmission of data  key elements of a protocol:  syntax  semantics  Timing/synchronization McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  46. 46. Protocols and Standards  Standards  provide guidelines to create and maintain an open competitive market  categories:  De Facto  De Jure  Standards Creation Committees  International Organization for Standardization (ISO)  International Telecommunication Union (ITU)  Consultative Committee for International Telegraphy and Telephony (CCITT)  American National Standard Institute (ANSI)  Institute of Electrical and Electronics Engineers (IEEE)  Electronics Industries Association (EIA) McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  47. 47. Protocols and Standards  Standards  Forums  made up of representatives from interested corporations  test, evaluate and standardized new technologies  present their conclusion to standards bodies  Regulator Agencies  communication technology is regulated by government agencies  protect public interest by regulating radio, TV & cable  Federal Communications Commission (FCC) - USA  National Telecommunication Commission (NTC) - PHIL McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  48. 48. NNoottee:: End of Chapter 1 McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  49. 49. Chapter Questions: Q.1) Which of the following are types of computer networks? A. LAN, NAN, WAN B. WAN, ring, star, bus C. old boys' network, old girls' network, business associates D. extranet, intranet, LAN, WAN Q.2) Which of the following is the best description of the transmission directions possible in a network? A. simplex, half-duplex, full duplex B. simplex, half-duplex, full duplex, duplex C. half duplex, 2/3 duplex, full duplex D. duplex, half duplex, 1/4 duplex Q.3) Which of the following is NOT a list of network topologies? A. star, bus, ring B. star, ring, hybrid C. bus, ring, double ring, hexagon D. ring, mesh, star, bus, Q.4) Which network topology has a central device which brings all the signals together? A. bus B. star C. ring D. hybrid Q.5) Which network topology requires terminators at the ends of the lines? A. ring B. bus C. star D. mesh Q.6) A blank is a number of computers linked together to allow them to share data and/or other resources. words or 1 word ) Q.7) All communication systems must have a sender, a receiver and a blank. ( 2 words or 1 word ) Q.8) What is being described here -> pairs of copper wires twisted around each other. ( 3 words or 2 words ) Q.9) This cable uses light to transmit data instead of magnetic signals. ( 3 words or 2 words or 1 word ) Q.10) A blank converts digital signals to analogue signals and also analogue signals to digital signals . ( 1 word ) McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
  50. 50. Chapter Questions: 1. Identify the five properties of a data communications system. 2. Name four basic network topologies, and cite an advantage of each. 3. Why are protocols needed? McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

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