Introduction to data communication system.ppt

Introduction to data communication system.ppt

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  1.1 Chapter 1 Introduction Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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  1.2 1-1 DATA COMMUNICATIONS 1-1DATA COMMUNICATIONS The term The term telecommunication telecommunication means communication at a means communication at a distance. The word distance. The word data data refers to information presented refers to information presented in whatever form is agreed upon by the parties creating in whatever form is agreed upon by the parties creating and using the data. and using the data. Data communications Data communications are the are the exchange of data between two devices via some form of exchange of data between two devices via some form of transmission medium such as a wire cable. transmission medium such as a wire cable.  Components of a data communications system  Data Flow Topics discussed in this section: Topics discussed in this section:
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  1.3 Figure 1.1 Componentsof a data communication system
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  1.4 Figure 1.2 Dataflow (simplex, half-duplex, and full-duplex)
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  1.5 1-2 NETWORKS 1-2 NETWORKS A Anetwork network is a set of devices (often referred to as is a set of devices (often referred to as nodes nodes) ) connected by communication connected by communication links links. A node can be a . A node can be a computer, printer, or any other device capable of sending computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the and/or receiving data generated by other nodes on the network. A link can be a cable, air, optical fiber, or any network. A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying medium which can transport a signal carrying information. information.  Network Criteria  Physical Structures  Categories of Networks Topics discussed in this section: Topics discussed in this section:
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  1.6 Network Criteria  Performance Depends on Network Elements  Measured in terms of Delay and Throughput  Reliability  Failure rate of network components  Measured in terms of availability/robustness  Security  Data protection against corruption/loss of data due to:  Errors  Malicious users
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  1.7 Physical Structures  Typeof Connection  Point to Point - single transmitter and receiver  Multipoint - multiple recipients of single transmission  Physical Topology  Connection of devices  Type of transmission - unicast, mulitcast, broadcast
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  1.8 Figure 1.3 Typesof connections: point-to-point and multipoint
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  1.9 Figure 1.4 Categoriesof topology
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  1.10 Figure 1.5 Afully connected mesh topology (five devices)
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  1.11 Figure 1.6 Astar topology connecting four stations
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  1.12 Figure 1.7 Abus topology connecting three stations
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  1.13 Figure 1.8 Aring topology connecting six stations
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  1.14 Figure 1.9 Ahybrid topology: a star backbone with three bus networks
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  1.15 Categories of Networks Local Area Networks (LANs)  Short distances  Designed to provide local interconnectivity  Wide Area Networks (WANs)  Long distances  Provide connectivity over large areas  Metropolitan Area Networks (MANs)  Provide connectivity over areas such as a city, a campus
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  1.16 Figure 1.10 Anisolated LAN connecting 12 computers to a hub in a closet
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  1.17 Figure 1.11 WANs:a switched WAN and a point-to-point WAN
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  1.18 Figure 1.12 Aheterogeneous network made of four WANs and two LANs
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  1.19 1-3 THE INTERNET 1-3THE INTERNET The The Internet Internet has revolutionized many aspects of our daily has revolutionized many aspects of our daily lives. It has affected the way we do business as well as the lives. It has affected the way we do business as well as the way we spend our leisure time. The Internet is a way we spend our leisure time. The Internet is a communication system that has brought a wealth of communication 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. Organization of the Internet Internet Service Providers (ISPs) Topics discussed in this section: Topics discussed in this section:
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  1.20 Figure 1.13 Hierarchicalorganization of the Internet
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  1.21 1-4 PROTOCOLS 1-4 PROTOCOLS Aprotocol is synonymous with rule. It consists of a set of A protocol is synonymous with rule. It consists of a set of rules that govern data communications. It determines rules that govern data communications. It determines what is communicated, how it is communicated and when what is communicated, how it is communicated and when it is communicated. The key elements of a protocol are it is communicated. The key elements of a protocol are syntax, semantics and timing syntax, semantics and timing  Syntax  Semantics  Timing Topics discussed in this section: Topics discussed in this section:
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  1.22 Elements of aProtocol  Syntax  Structure or format of the data  Indicates how to read the bits - field delineation  Semantics  Interprets the meaning of the bits  Knows which fields define what action  Timing  When data should be sent and what  Speed at which data should be sent or speed at which it is being received.