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Unformatted text preview: Chapter 6 – Networks and Communications Technology WHY SHOULD I CARE ABOUT NE TWORKS The Global positioning system (GPS) uses a collection of dozens of satellites orbiting the earth that transmit precise microwave signals. A GPS receiver can calculate its position by measuring the distance between itself and several of the satellites. With microwave signals from at least 3 satellites, you can compute a GPS receiver’s position. The GPS can even calculate the direction and speed of a GPS receiver. Combining the GPS with a map database enables the development of automobile navigation systems (ANS). These ANS sell for a few hundred dollars and help guide car drivers from point A to point B in real time. WHAT IS A COMPUTER NETWORK A computer network is a collection of computers that communicate with one another over transmission media. The 3 basic types of networks are: o Local area networks – which connect computers that reside in a single geographic location on the premises of the company that operates the LAN. The number of connected computers can range from 2 to several hundred. o Wide area networks connect computers at different geographic locations. The distinguished characteristic of a LAN is a single location. • With an LAN, an organization can place communications lines wherever it wants, because all lines reside on its premises. The same is not true for a WAN, which is why there is the Internet. o An internet is a network of networks. Internets connect LANs, WANs, and other internets. The most famous internet is the Internet (with an upper case I), the collection of networks that you use when you send email or access a website. In addition to the Internet, private networks of networks, called internets, also exist • The networks that comprise an internet use a large variety of communication methods and conventions, and data must flow seamlessly across them. To provide seamless flow, an elaborate scheme called a layered protocol is used. • A protocol is a set of rules that 2 communicating devices follow. The important point is that for 2 devices to communicate, they must both use the same protocol. WHAT ARE T HE COMPONENTS OF A LAN A LAN is a group of computers connected together on a single company site. Usually the computers are located within a kilometre or so of each other, although longer distances are possible. A switch is a special purpose computer that receives and transmits messages on the LAN. Ex: computer 1 accesses printer 1 by sending the job to the switch, which then redirects that data to Printer 1. In a building with several floors, a switch is placed on each floor, and the switches are then connected to a main switch which is often located in the basement....
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This note was uploaded on 03/23/2010 for the course COMP SCI 1032 taught by Professor Goldstein during the Winter '10 term at UWO.
- Winter '10