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  1. 1. CHAPTER 3: COMPUTERNETWORKS ANDCOMMUNICATIONSBasic Concepts of Computer Networks
  2. 2. Definition of Computer NetworksA computer network is a Devices – printer, scannercollection of computers Communication devicesand devices NIC Routerconnected together via Hub ?? ??communication devices Transmission Mediaand transmission media.For examples it may Physicalconnect computers, Infraredprinters and scanners. Radiowave Satellite
  3. 3. Definition of CommunicationCommunication describes a process in which two ormore computer or devices transfer data, instructionsand information.
  4. 4. The Importance/Advantage of Computer Networkss Sharing of devices such as printer and scannera Sharing of program/softwarea Sharing of files, Sharing of dataa Sharing of information, Sharing of single high-speed internet connectiond Can access server centered databaseB Better communication using internet services such as email, mailing list and Internet Relat Chat (IRC)
  5. 5. Types of Computer Networks A local area network is a network that connectsLocal Area Network (LAN) computers and device in a limited geographical area such as a home, school computer laboratory, office building
  6. 6. A metropolitan area network (MAN) is a high speedMetropolitan Area network that connects local area networks in a Network (MAN) metropolitan area such as city or town and handles bulk of communication activity across the region A MAN typically includes one or more LAN but covers a smaller geographic area than a WAN
  7. 7. A wide area network is a network that covers a largeWide Area Network geographical area such country or the world (WAN) WAN combines many types of media such as telephone lines, cables and radio wave. A WAN can be one large network or can consist of two or more LANs connected together The internet is the worlds largest WAN
  8. 8. Differentiate between the types of Computer Networks Different LAN MAN WAN Cost Low optic High HigherNetwork Size Small Larger Largest Speed Fastest Slower SlowestTransmission Twisted-pair Twisted-pair Fiber optic Media Fibre-optic cables Radio wave Satellite Number of Smallest Large Largest Computers
  9. 9. Network Architecture Network architecture is the overall design of a computer network that describes how a computer network is configured and what strategies are being used. It is mainly focuses on the function of the networks. It is also known as network model or network design. Two main network architecture:
  10. 10. A server is a computer that provides services to clients and controls access to hardware, software and other resourcesA client is a computerthat request servicesfrom a server computer
  11. 11. On a client/server network, one computer act as a serverClient/Server that provides services and the other computers (client) on the network request services from the server. A server is a computer that controls access to the hardware, software and other resources on the network and provides a centralized storage area for program. A client is a computer that request services from a server computer. Peer-to-peer is a simple, inexpensive network thatPeer-to-Peer typically connects fewer than 10 computers. All computers in the network have equal capabilities to use the resources (hardware, software, data and file) available on the network. With peer-to-peer networks, there is no central server.
  12. 12. The Differences between Client/Server and Peer-to-Peer Client/Server Peer-to-Peer1) Server has to control ability 1) All computers have equal while client’s don’t ability2) Higher cabling cost 2) Cheaper cabling cost3) It is used in small and large 3) Normally used in small networks networks with less than 104) Easy to manage computers5) Install software only in the 4) Hard to manage server while the clients share 5) Install software to every the software computer6) One powerful computer 6) No server is needed acting as server