1. Communications & Networks National 4 & 5 Computing Science

2. Revision 1. What is a network? Group of computers linked together to share data, send emails, share devices 2. What is a LAN? Local Area Network, contained within a room or building 3. What is a WAN? Wide Area Network, large geographic area – country or continent 4. What network setup uses a server to deal with all network requests? Client/Server setup – Server deals with requests for files, sends emails 5. What is one difference between the Client/Server and Peer-to-Peer setup? Client server – central backup, users can use other computers on the network, more secure

3. Learning Intentions What we will learn: What is transmission medium What is bandwidth How to connect a LAN What is a Wide Area Network - WAN How to connect a WAN

4. Learning Objectives Know what transmission media is and when it is used Know what bandwidth is and how it affects the network Understand the methods of connecting a LAN Be able to identify a Wide Area Network Understand the methods of connecting a WAN

5. What is Transmission Medium Transmission medium is the material used to carry data over the network. There are two main forms, which are: Wired – using cables Wireless – WiFi

6. Bandwidth Bandwidth is the amount of data that can be carried over a network at any one time. Data transfer speed means the same as bandwidth It is measured in: Mbps – Megabits per second Gbps – Gigabits per second

7. Connecting a LAN - Wired Two types of cables most commonly used are: Unshielded twisted pair (UTP) – Copper wire Prone to interference – data carried using electrical signals Can be tapped Is fairly cheap to install Optical Fibre Fine strands of glass – data carried using beams of light Although more expensive does not corrode Secure data transmission Much higher bandwidth over a much longer distance

8. Connecting a LAN - Wireless Possible methods of data transmission are: Bluetooth Temporary short-range links between devices such as mobile phones, headsets, laptops Have a maximum range of 10 meters Transfer rate od between 1 and 3 Mbps WiFi Used in laptop computers, wireless routers, mobile phones and game consoles Home WiFi should be protected with a hard-to-guess password to prevent other people from using your broadband If your broadband is stolen in this way they may be liable for prosecution, however, if they use it to do something illegal you may be held responsible

9. Wide Area Network (WAN) Connects computers over large areas Spread across countries and cities around the world Similar to a local area network but on a larger scale

10. Connecting a Wide Area Network(WAN) Wide Area Networks use telecommunications links to transmit and receive data, which includes: Satellite links Also used by the public telephone service for international communication These links use highly directional, narrow beam, two-way transmissions A single satellite channel can carry a large number of separate transmissions Microwave transmission Use dish aerials and are highly directional Used by the public telephone service

11. Connecting a Wide Area Network(WAN) Optical Fibre Submarine cables – under the sea

12. Success Criteria I … Know what transmission media is and how it is used Know what bandwidth is and how it affects the network Understand the methods of connecting a LAN Be able to identify a Wide Area Network Understand the methods of connecting a WAN Know various methods of securing a network