CS.5 Computer Communication and Networking

By Rico Yu

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

The need for networking

Hardware sharing Communication Data and information sharing

Hardware sharing

Communication

Use network to communicate between users E-mail (電子郵件 )

Data and information sharing

Share data, files or programs E.g.

POS system Airline reservation system

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)

Local Area NetworkLocal Area NetworkNNAALL NNAALL NNAALL NNAALL - Within a room, floor or building

FAST!

FAST!

Server based network

Peer-to-peer network

Terminal network

LANLANLANLAN

LANLAN

I Love U !I Love U too !

Wide Area NetworkWide Area NetworkNNAAWW NNAAWW NNAAWW NNAAWW - link small networks in different geographic area

Media of transmission in a network

1. Twisted pair cables

2. Coaxial cable

3. Optical fibres

4. Microwaves

5. Satellites

1. Twisted pair cables (UTP cables)

Cheapest transmission medium

Susceptible to local electrical noises

Usually used for short distance

connections such as telephone line

2. Coaxial cable

Fairly cheap transmission

mediumAn insulating material protect the copper wire

Used for connecting a TV

set to public antennaMore reliable as

it is better insulated

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

4. Microwaves

5. Satellite transmission

Ground station receive the data and beam to the satellite by microwave

Satellite will re-transmit data to another ground station

5. Satellite transmission

Other network devices

1. Modem

2. Server

3. Workstation

4. Network card

5. Hub or switch

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

1. Modem

Modulation : digital signals are converted to analogue signals

Demodulation : analogue signals are converted to digital signals.

1. Modem