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Chapter 6

Chapter 6. Telecommunications and Networks. Learning Objectives. Understand the concept of a network. Apply Metcalfe’s law in understanding the value of a network.

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Chapter 6

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  1. Chapter 6 Telecommunications and Networks

  2. Learning Objectives • Understand the concept of a network. • Apply Metcalfe’s law in understanding the value of a network. • Identify several major developments and trends in the industries, technologies, and business applications of telecommunications and Internet technologies. • Provide examples of the business value of Internet, intranet, and extranet applications.

  3. Learning Objectives • Identify the basic components, functions, and types of telecommunications networks used in business. • Explain the functions of major components of telecommunications network hardware, software, media, and services. • Explain the concept of client/server networking. • Understand the two forms of peer-to-peer networking. • Explain the difference between digital and analog signals.

  4. Learning Objectives • Identify the various transmission media and topologies used in telecommunications networks. • Understand the fundamentals of wireless network technologies. • Explain the concepts behind TCP/IP. • Understand the seven layers of the OSI network model.

  5. Network Concepts • Network • An interconnected chain, group or system • Number of possible connections on a network is N * (N-1) • Where N = number of nodes (points of connections on the network) • Example, if there are 10 computers on a network, there are 10 * 9 = 90 possible connections

  6. Metcalfe’s Law • The usefulness of a network equals the square of the number of users • On a small network, a change in technology affects technology only • On a large network like the Internet, a change in technology affects social, political and economic systems

  7. Telecommunications • Telecommunications • Exchange of information in any form (voice, data, text, images, audio, video) over networks

  8. Trends in Telecommunications

  9. Open Systems • Information systems that use common standards for hardware, software, applications and networks • Internet networking technologies are a common standard for open systems • Connectivity: • Ability of networked computers to easily access and communicate with each other and share information • Interoperability: • The ability of an open system to enable end user applications to be accomplished using different varieties of computer systems, software packages, and databases provided by a variety of interconnected networks

  10. Middleware • Any programming that serves to “glue together” two separate programs

  11. Digital Network Technologies • Rapid change from analog to digital network technologies • Analog: voice-oriented transmission, sound waves • Digital: discrete pulse transmission • Digital allows: • Higher transmission speed • Larger amounts of information • Greater economy • Lower error rates • Multiple forms of communications on same circuit

  12. Internet2 • Next generation of the Internet • High-performance network • In use at 200 universities, scientific institutions, communications corporations

  13. Business Value of Telecommunication Networks

  14. The Internet • Over 46 million servers (2004) • 710 – 945 million users (2004) • No central computer system • No governing body • No one owns it

  15. Internet Service Provider • ISP • A company that specializes in providing easy access to the Internet • For a monthly fee, you get software, user name, password and access • ISPs are connect to one another through network access points

  16. Popular uses of the Internet

  17. Using the Internet for business

  18. Business value of the Internet

  19. An Intranet • A network inside an organization • That uses Internet technologies (such as Web browsers and servers, TCP/IP protocols, HTML, etc.) • To provide an Internet-like environment within the organization • For information sharing, communications, collaboration and support of business processes • Protected by security measures • Can be accessed by authorized users through the Internet

  20. Enterprise Information Portal

  21. Extranet • Network links that use Internet technologies • To connect the Intranet of a business • With the Intranets of its customers, suppliers or other business partners

  22. Extranet Uses

  23. Telecommunications network • Any arrangement where a sender transmits a message to a receiver over a channel consisting of some type of medium

  24. Telecommunications network components • Terminals: any input/output device that uses networks to transmit or receive data • Telecommunications Processors: devices that support data transmission and reception • Telecommunications Channels: media over which data are transmitted and received • Computers: all sizes and types • Telecommunications Control Software: programs that control telecommunications activities

  25. Telecommunications network model

  26. Wide Area Network (WAN) • Telecommunications network that covers a large geographic area Source: Courtesy of Cisco Systems Inc.

  27. Local Area Network (LAN) • Connect computers within a limited physical area such as an office, classroom, or building

  28. Virtual Private Networks (VPN) • A secure network that uses the Internet as its backbone but relies on firewalls, encryption and other security • A pipe traveling through the Internet

  29. VPN

  30. Client/Server networks • Clients: End user personal computers or networked computers • Interconnected by LANs • Servers: manage networks • Processing shared between clients and servers

  31. Client/Server Network

  32. Network Computing • Networks are the central computing resource of the organization • Thin clients: network computers and other clients provide a browser-based user interface

  33. Peer-to-peer networks • Networks that connect from one PC to another PC • Common use is the downloading and trading of files

  34. Peer-to-Peer Network

  35. Telecommunications Media • Twisted-pair wire: • Ordinary telephone wire • Copper wire twisted into pairs Source: Phil Degginger/Getty Images.

  36. Telecommunications Media • Coaxial cable: • Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Source: Ryan McVay/Getty Images.

  37. Telecommunications Media • Fiber-optic cable: • One or more hair-thin filaments of glass fiber wrapped in a protective jacket Source: CMCD/Getty Images.

  38. Problem of “The Last Mile” • Network providers use fiber optic to provide backbone • But houses are connected to the backbone via twisted-pair • Cannot get the benefit of the faster, better technology

  39. Wireless Technologies • Terrestrial microwave • Earthbound microwave systems that transmit high-speed radio signals in a line-of-sight path • Between relay systems spaced approximately 30-miles apart • Communications satellites • Satellite serves as relay stations for communications signals • Uses microwave radio signals

  40. Wireless Technologies • Cellular and PCS telephone and pager systems • Divide the geographic area into small areas or cells • Each cell has transmitter or radio relay antenna to send message from one cell to another • Wireless LANs • Radio signals within an office or building • Connect PCs to networks • Bluetooth • Short-range wireless technology • To connect PC to peripherals such as printer

  41. Wireless Web • Connect portable communications devices to the Internet

  42. Telecommunications Processors • Modems • Convert digital signals from a computer into • Analog frequencies that can be transmitted over ordinary telephone lines

  43. Comparing modem and other technologies

  44. Internetwork Processors • Switch – makes connections between telecommunications circuits in a network • Router – intelligent communications processor that interconnects networks based on different protocols • Hub – a port switching communications processor • Gateway – connects networks using different communications architectures

  45. Communications Processors

  46. Telecommunications Processors • Multiplexer • Allows a single communications channel to carry simultaneous data transmissions from many terminals

  47. Telecommunications Software • Used by servers and other computers to manage network performance • Network Operating Systems • Middleware

  48. Network management functions • Traffic Management – manage network resources and traffic to avoid congestion and optimize service levels to users • Security – provide authentication, encryption, firewall, auditing and enforcement • Network Monitoring – troubleshoot and watch over the network, informing network administrators of potential problems before they occur • Capacity Planning – survey network resources and traffic patterns and users’ needs to determine how best to accommodate the needs of the network as it grows and changes

  49. Network Topologies Topology: structure of a network Star: ties end user computers to a central computer Ring: ties local computer processors together in a ring on a relatively equal basis Bus: local processors share the same communications channel

  50. Network Topologies

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