1. 1 CHAPTER 8 TELECOMMUNICATIONSANDNETWORKS

2. 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. 3 Text Voice Image Video Types of Data

4. 4 SENDER RECEIVER MEDIUM Basic Communications Model

5. 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. 6 Figure 8-1 COMPONENTS OF A TELECOMMUNICATIONS SYSTEM

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

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

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

10. 10 Analogue signal: a continuous wave Digital: a discrete set of on (1) and off (0) electronic bursts rather than a continuous wave. +1 0 0 11 0 Analog and digital signals

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

13. 13 Twisted Pair Coaxial Cable Optical Fiber Guided Media

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

15. 15 Unguided Media: Satellite

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18. 18 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 COMMUNICATIONS CHANNELS

19. 19 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 COMMUNICATIONS PROCESSORS AND SOFTWARE

20. 20  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 Computer Networks

21. 21 Network Topology: STAR

22. 22 Network Topology: Bus

23. 23 Network Topology: Ring

24. 24 Each node is connected to each other node in the network Global Storage Medium Shared Printer Network Topology: Mesh

25. 25 Network Architecture: e.g., Client-Server Server provides global information and software, manages the use of shared printers, provides communication within and external to the network.

26. 26 The host computer handles all information processing, manages communication, and stores all software and information. Network Architecture: e.g., Centralized Network

27. 27 Private Branch Exchanges Central switching system Handle firm’s voice and digital communications COMMUNICATIONS NETWORKS

28. 28 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) COMMUNICATIONS NETWORKS

29. 29 A Local Area Network (LAN) Figure 8-8 COMMUNICATIONS NETWORKS

30. 30 Wide Area Networks (WANs) Span large geographical distance Consist of variety of switched and dedicated lines, satellite, and microwave technologies COMMUNICATIONS NETWORKS

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34. 34 Network Services Value Added Networks: private, multipath, data only, third party managed networks Packet switching technology Frame Relay Asynchronous transfer mode (ATM) COMMUNICATIONS NETWORKS

35. 35 Models of Connectivity for Networks Transmission Control Protocol/Internet Protocol (TCP/IP) Open Systems Interconnect (OSI) Standards and Connectivity for Digital Integration

36. 36 (TCP/IP) Reference Model Figure 9-2 Standards and Connectivity for Digital Integration

37. 37 Application TCP IP Data Link Physical layer Application protocol Transport protocol IP protocol Data Link protocol Physical medium: e.g., Ethernet cable PC-1 PC-2 PC to PC Communication using TCP/IP RequestHTTP TCP RequestHTTP IPTCP RequestHTTP Ethernet IPTCP RequestHTTP RequestHTTP TCP RequestHTTP IPTCP RequestHTTP Ethernet IPTCP RequestHTTP

38. 38 Packed-Switched Networks and Packet Communications Figure 8-9 COMMUNICATIONS NETWORKS

39. 39 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 Switch A B C D E Trunk Line

40. 40 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 Switch Trunk Line Switch A BC D E

41. 41 EDI Direct computer to computer exchange between two organizations of standard business transaction documents Lower transaction cost Provide strategic benefits by increasing switching cost ELECTRONIC DATA INTERCHANGE