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  1. 1. Chapter 4 SC161: Principles of Information Technology Communication and Network Part 2: Computer Network Thiti Theerathean Center for Teaching Excellence University of the Thai Chamber of Commerce E-mail :
  2. 2. 2 • Introduction to Computer Network. - Types of Computer Network. - The basic Configurationsof Computer Network. - The Benefits of Computer Network. • Network Architecture Model. - OSI Model. - InternetModel. • Local Area Network. - The Components of LAN. - Topologies of LAN. • Wide Area Network. - TransmissionFacility. - Modulation. - Multiplexing. SC161: Principlesof Information Technology
  3. 3. 3SC161: Principlesof Information Technology A Computer network is an interconnection of computers and computing equipment using either wire and wireless over small or large geographic areas. Twisted pair, Radio wave Coaxial, Fiber Optic Fiber Optic, Microwave
  4. 4. 4SC161: Principlesof Information Technology Personal Area Network : PAN A personal area network is a computer network organized around an individual person. PANs typically involve a mobile computer, a cell phone or a handheld computing device such as a PDA. Bluetooth PANs are also called piconet.
  5. 5. 5SC161: Principlesof Information Technology The Big Picture of Computer Network.
  6. 6. 6SC161: Principlesof Information Technology The Basic Configurations of Computer Network. PCs to LAN LAN to LANs
  7. 7. 7SC161: Principlesof Information Technology The Basic Configurations of Computer Network. PC to WAN LAN to WAN
  8. 8. 8SC161: Principlesof Information Technology The Benefits of Computer Network People and Organizations use networks for the following reason, the most important of which is the sharing of resource. • Resource sharing • Data and information sharing • Better Communications • Reduced Cost • On-line services • Electronic data interchange
  9. 9. 9SC161: Principlesof Information Technology
  10. 10. 10SC161: Principlesof Information Technology How do you sends a message to your friends ? Message. Department. Company. POST Code. Country. Thiti Theerathean. Faculty of Science. University of the Thai Chamber of Commerce. Vibhavadee-Rangsit Rd. Dindang Department of Information & Communication Technology. Bangkok 10400 Thailand Application Set Transport Set
  11. 11. 11SC161: Principlesof Information Technology The Open Systems Interconnection Reference Model The architectural model adopted by the International Standards Organization (OSI) . Bits Frame Packet Segment Data Application Set Transport Set
  12. 12. 12SC161: Principlesof Information Technology The Open Systems Interconnection Reference Model Application Interface. Web browser, File Transfer, e-Mail Application Layer Presentation Layer Encryption Data. ASCII, EBCDIC, UNICODE Session Layer Transmission Control. Simplex, Half-duplex, Full-duplexApplication Set Transport Set Transport Layer Flow Control. Connection-Oriented, Connectionless Network Layer Routes data. IP Address Data Link Layer Node to Node Transmission. MAC Address Physical Layer Send and Receive Bits. Signal and Media.
  13. 13. 13SC161: Principlesof Information Technology The Internet Model The Internet model is a most widely used that it is accepted as a network architecture. The Internet’s Protocol suite is called Transmission Control Protocol/Internet Protocol (TCP/IP). OSI Model Internet Model Protocols HTTP FTP POP3 DNS TCP UDP IPv4 IPv6 ICMP Not Specified User Data Datagram Packet Segment Encapsulation
  14. 14. 14SC161: Principlesof Information Technology The Internet Model in Action. Router Router Link Layer Internet Layer Transport Layer Application Layer Application Layer Transport Layer Internet Layer Internet Layer Internet Layer Link Layer Link Layer Link Layer Link Layer Link Layer
  15. 15. 15SC161: Principlesof Information Technology
  16. 16. 16SC161: Principlesof Information Technology A Local Area Network (LAN) is a communication network that interconnects a variety of data communicating devices within a small geographic area and broadcasts data at high data transfer rates with very low error rates.
  17. 17. 17SC161: Principlesof Information Technology Client/Server Microcomputer users, or clients, share services of a centralized computer called a server. Peer-to-Peer Computers share equally with one another without having to rely on a central server.
  18. 18. 18SC161: Principlesof Information Technology A Topology is the physical layout of nodes in a network, which often dictates the type of communications protocol used by the network. Topologies of LANs. Three Network Topologies.
  19. 19. 19SC161: Principlesof Information Technology T-Connector BUS Desktop Computer Terminator • All nodes are connected to a single wire or cable, called a Backbone. • Node is connected to a backbone with T-connector. • Terminators are required at both ends of the backbone cable. • A message (signal) that is sent by a node travels along the bus through all other nodes.
  20. 20. 20SC161: Principlesof Information Technology Server Desktop Computer RING • All the nodes are connected in a closed circle of cable. • Electronic messages are passed around the ring. • The Token determines which user on the network can send information. It is called “Token passing”
  21. 21. 21SC161: Principlesof Information Technology • All devices connected with a central Hub. • The Hub monitors the flow of traffic. • The Hub also acts as a repeater for the data flow and then retransmits the signals to all other nodes. Server HUB Desktop Computer
  22. 22. 22SC161: Principlesof Information Technology
  23. 23. 23SC161: Principlesof Information Technology A Wide Area Network (WAN) is a data communications network that covers a relativelybroad geographicarea and that often uses transmissionfacilitiesprovided by common carriers such as telephone companies. A WAN is contrasted to smaller Local Area Networks (LANs) and Metropolitan Area Networks (MANs). Home Network Company Network Internet Service Provider (ISP) InternetSatellite
  24. 24. 24SC161: Principlesof Information Technology Transmission Facility. What is the most efficient way to send message over a WAN network ?
  25. 25. 25SC161: Principlesof Information Technology Transmission Facility. Circuit switching : Best for voice. Message
  26. 26. 26SC161: Principlesof Information Technology Transmission Facility. Packet switching : Best for data. 1 2 3
  27. 27. 27SC161: Principlesof Information Technology Modulation. The telephone system transmit analog signals, the transfer of a computer’s digital data over a telephone line requires conversion of the data to an analog signal. • The technique of converting digital data to an analog signal is called “modulation”. • The technique of converting analog signal back to digital data is called “demodulation” Analog signal Digital signal Modem Modulates Signal Modem Demodulates Signal
  28. 28. 28SC161: Principlesof Information Technology Multiplexing. The multiplexing is a technique of transmitting multiple signals over a single medium. It is performed at the physical layer of the OSI model. For multiple signals to share one medium. The medium must be divided. Frequency Division Multiplexing Time Division Multiplexing
  29. 29. 29SC161: Principlesof Information Technology