2. CS.5 Computer Communication and Networking By Rico Yu

3.  The need for networking  Type of network  Media of transmission in a network  Other network devices  The use of protocol  E.g. of computer communication CS.5 Computer Communication and Networking

4. The need for networking  Hardware sharing  Communication  Data and information sharing

5. Hardware sharing

6. Communication  Use network to communicate between users  E-mail ( 電子郵件 )

7. Data and information sharing  Share data, files or programs  E.g. POS system Airline reservation system

8. Type of network 1.Local Area Network (LAN) a) Server based network b) Peer-to-peer network c) Terminal network 2.Wide Area Network (WAN)

9. Local Area Network NALNALNALNAL - Within a room, floor or building FAST!

10. Server based network

11. Peer-to-peer network

12. Terminal network

13. LAN LAN LAN I Love U !I Love U too ! Wide Area Network NAWNAWNAWNAW - link small networks in different geographic area

14. Media of transmission in a network 1.Twisted pair cables 2.Coaxial cable 3.Optical fibres 4.Microwaves 5.Satellites

15. 1.Twisted pair cables (UTP cables) Cheapest transmission medium Susceptible to local electrical noises Usually used for short distance connections such as telephone line

16. 2. Coaxial cable Fairly cheap transmission medium An insulating material protect the copper wire Used for connecting a TV set to public antenna More reliable as it is better insulated

17. 3. Optical fibres - Light passes along the coated fine cylindrical glass tubing by reflection Very expensive transmission medium Not subject to electrical disturbance Suited for long distances communication in high data rate

18. 4. Microwaves

19. 5. Satellite transmission

20. Ground station receive the data and beam to the satellite by microwave Satellite will re- transmit data to another ground station 5. Satellite transmission

21. Other network devices 1.Modem 2.Server 3.Workstation 4.Network card 5.Hub or switch

22. When two computers communicate to each other over a telephone lines, a modem is required for modulation and demodulation of signals. 1. Modem

23. Modulation : digital signals are converted to analogue signals Demodulation : analogue signals are converted to digital signals. 1. Modem