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CHAPTER 8 TELECOMMUNICATIONS AND NETWORKS

CHAPTER 8 TELECOMMUNICATIONS AND NETWORKS. TELECOMMUNICATIONS. Telecommunications: Communication of all types of information, including digital data, voice, fax, sound, and video from one location to another over some type of network

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CHAPTER 8 TELECOMMUNICATIONS AND NETWORKS

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  1. CHAPTER 8 TELECOMMUNICATIONS AND NETWORKS

  2. TELECOMMUNICATIONS • Telecommunications: Communication of all types of information, including digital data, voice, fax, sound, and video from one location to another over some type of network • Network: A group of computers and associated peripheral devices connected by a communication channel of sharing information and other resources among users

  3. Types of Data • Text • Voice • Image • Video

  4. RECEIVER Basic Communications Model SENDER MEDIUM

  5. COMPONENTS OF A TELECOMMUNICATIONS SYSTEM • Computers to process information • Terminals or any input/output devices that send or receive data • Communications processors • Communications software

  6. Figure 8-1 COMPONENTS OF A TELECOMMUNICATIONS SYSTEM

  7. Basic components of a data communications system Data communications processors PC PC Data communications Medium

  8. FUNCTIONS OF A TELECOMMUNICATIONS SYSTEM • Transmit information • Establish interface between sender and the receiver • Route messages along most efficient paths

  9. FUNCTIONS OF A TELECOMMUNICATIONS SYSTEM • Perform elementary processing of information • Perform editorial tasks on data • Convert message speed or format • Control flow of information

  10. Analog and digital signals • Analogue signal: a continuous wave • Digital: a discrete set of on (1) and off (0) electronic bursts rather than a continuous wave. +1 0 1 1 0 0

  11. Digital Digital Analog Modem Modem Medium: phone network

  12. Communication Media/Channels • Guided Media: • Twisted Pair • Coaxial Cable • Optical Fiber • Unguided Media: • Microwave • Satellite • Broadcast Radio

  13. Twisted Pair Coaxial Cable Optical Fiber Guided Media

  14. Unguided Media: Microwave • Microwave- “Line of sight” media: • antennas need to see each other

  15. Unguided Media: Satellite

  16. COMMUNICATIONS CHANNELS Transmission Speed • Total amount of info that can be transmitted through any channel is measured in bits per second • Baud: change in signal from + to – or vice versa that is used as a measure of transmission speed • Frequency: the number of cycles per second that can be sent through that medium (in hertz) • Bandwidth: the range of frequencies that can be accommodated on a particular communication channel

  17. COMMUNICATIONS PROCESSORS AND SOFTWARE • Front-end processor: Manages communications for the host computer • Concentrator: Collects and temporarily stores messages • Controller: Supervises communication traffic between CPU and peripheral devices • Multiplexer: Enables single communication channel to carry data transmissions from multiple sources simultaneously

  18. Computer Networks • By geographic span • Local Area Network (LAN) • Wide Area Network (WAN) • By topology (physical) • Star • Bus • Ring • Mesh • By architecture (logical) • Peer to peer versus client-server • Centralized versus distributed versus hybrid

  19. Network Topology: STAR

  20. Network Topology: Bus

  21. Network Topology: Ring

  22. Network Topology: Mesh Each node is connected to each other node in the network Global Storage Medium Shared Printer

  23. Server • provides global information and software, • manages the use of shared printers, • provides communication within and external • to the network. Network Architecture: e.g., Client-Server

  24. Network Architecture: e.g., Centralized Network The host computer handles all information processing, manages communication, and stores all software and information.

  25. COMMUNICATIONS NETWORKS Private Branch Exchanges • Central switching system • Handle firm’s voice and digital communications

  26. COMMUNICATIONS NETWORKS Local Area Networks • Encompass a limited distance • Require its own communication channels • Support high volumes of data and functions requiring high transmission speed • Gateway, router, Network Operating System (NOS)

  27. Figure 8-8 COMMUNICATIONS NETWORKS A Local Area Network (LAN)

  28. COMMUNICATIONS NETWORKS Wide Area Networks (WANs) • Span large geographical distance • Consist of variety of switched and dedicated lines, satellite, and microwave technologies

  29. Internet Architecture

  30. COMMUNICATIONS NETWORKS Network Services • Value Added Networks: private, multipath, data only, third party managed networks • Packet switching technology • Frame Relay • Asynchronous transfer mode (ATM)

  31. Standards and Connectivity for Digital Integration Models of Connectivity for Networks • Transmission Control Protocol/Internet Protocol (TCP/IP) • Open Systems Interconnect (OSI)

  32. Figure 9-2 Standards and Connectivity for Digital Integration (TCP/IP) Reference Model

  33. PC-1 PC-2 Application protocol HTTP HTTP HTTP HTTP HTTP HTTP HTTP HTTP Request Request Request Request Request Request Request Request Transport protocol TCP TCP TCP TCP TCP TCP IP protocol IP IP IP IP Data Link protocol Ethernet Ethernet Physical medium: e.g., Ethernet cable PC to PC Communication using TCP/IP Application TCP IP Data Link Physical layer

  34. Figure 8-9 COMMUNICATIONS NETWORKS Packed-Switched Networks and Packet Communications

  35. Packet Switching • Packet switching breaks transmissions into packets • When a packet arrives at a switch, the switch must decide where to send the packet next D E Switch Switch A Trunk Line C B

  36. Circuit Switching • End-to-end connection between phones • May pass through multiple switches and trunk lines • Reserved (guaranteed) capacity during call • Reserved circuit capacity is expensive • Good for voice/bad for data • Capacity is wasted between bursts, but still must pay for capacity D E Switch Trunk Line Switch A B C

  37. ELECTRONIC DATA INTERCHANGE EDI • Direct computer to computer exchange between two organizations of standard business transaction documents • Lower transaction cost • Provide strategic benefits by increasing switching cost

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