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Networks

Networks. A network is a collection of computers and devices connected together via communications devices and transmission media Advantages of a network include:. Bandwidth. Measurement of the capacity of the channel Categories Voiceband also known as low bandwidth Medium band

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Networks

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  1. Networks • A network is a collection of computers and devices connected together via communications devices and transmission media • Advantages of a network include:

  2. Bandwidth • Measurement of the capacity of the channel • Categories • Voiceband also known as low bandwidth • Medium band • Broadband • Used for high capacity transmission • Used by DSL, cable, and satellite

  3. Protocols • Set of communication rules • Standard for Internet: TCP/IP (Transmission controlprotocol/Internet protocol) • Identification • Reformatting

  4. Network Classifications • Local area networks (LAN) • Home networks • WLAN (Wireless LAN) • Metropolitan area networks (MAN) • Wide area networks (WAN)

  5. Network Classifications • A local area network(LAN) is a network that connects computers and devices in a limited geographical area • A wireless LAN (WLAN) is a LAN that uses no physical wires

  6. Network Classifications • A metropolitan area network (MAN) connects LANs in a metropolitan area • A wide area network (WAN) is a network that covers a large geographical area

  7. Network Architecture • The design of computers, devices, and media on a network is sometimes called the network architecture Client/server Peer-to-peer Terminal

  8. Peer-to-peer (P2P) Model Client/Server Model Peer Peer Client Client Peers communicate as equals on a one-to-one basis. Server Server must be prepared to serve multiple clients at any time. Client Client

  9. Examples: • file server • mail server • web server => The Client/Server Model • When processes need to communicate:

  10. The Client/Server Model (continued) • Client & server have strictly defined roles: • client sends request – then waits for answer • server accepts request – processes & returns answer • Protocols, defining how to: • encode messages • address messages • handle sending and receiving • Protocols: Example • http, ftp

  11. The Peer-to-peer Model • P2P describes an Internet network on which users access each other’s hard disks and exchange files directly over the Internet

  12. Network Topology • A network topologyrefers to the layout of the computers and devices in a communications network Star network Bus network Ring network

  13. Network Topology • Network topology is the layout pattern of interconnections of the various elements (links, nodes, etc.) of a computer. • Types of network topology • Star • Bus • Ring • Hierarchical

  14. Star Network • Smaller computers linked to a central unit • Central unit is called the network hub • Control is maintained by polling

  15. Bus Network • Each device handles its own communication control • There is no host computer • Has a common connecting cable called a backbone

  16. Ring Network • Each device is connected to two other devices • No central file server or computer • Useful in a decentralized environment

  17. Hierarchical Network • Several computers linked to a central host • Computers are hosts to other computers • Useful in centralized organizations Page 264

  18. Principal Network Configurations

  19. Network Communications Standards

  20. Network Communications Standards

  21. Network Communications Standards

  22. Network Communications Standards • Wi-Fiidentifies any network based on the 802.11 standard that facilitates wireless communication • Sometimes referred to as wireless Ethernet

  23. Network Communications Standards • Bluetooth defines how two Bluetooth devices use short-range radio waves to transmit data • UWB (ultra-wideband) specifies how two UWB devices use short-range radio waves to communicate at high speeds • IrDA transmits data wirelessly via infrared (IR) light waves • RFIDuses radio signals to communicate with a tag placed in or attached to an object, animal, or person

  24. Network Communications Standards

  25. Network Communications Standards

  26. Communications Software • Communications softwareconsists of programs that:

  27. Communications Over the Telephone Network • The public switched telephone network (PSTN) is the worldwide telephone system

  28. Communications Over the Telephone Network

  29. Communications Over the Telephone Network

  30. Communications Over the Telephone Network • ADSL connections transmit data downstream at a much faster rate than upstream

  31. Home Networks • Home networks provide computers with the following capabilities:

  32. Home Networks

  33. Organizational Internets • Intranets • Private network within an organization • Provides information to employees • Extranets • Private network that connects organizations • Used to allow suppliers and others access • Firewalls • Security system • Protects against external threats

  34. Careers In IT • Network Administrator • Manage a company’s LAN and WAN networks • Maintain hardware and software • Diagnose and repair problems • Candidates usually have a bachelor’s degree in computer science and practical experience • Annual salary is typically between $43,000 and $68,000

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