1. Networking Objectives Understand the three main networking topologies – Bus – Star – ring

2. Networking remember....What is a network? A computer network is where many computers are connected together. Networked computers can share files, offer services (such as email) and allow communication. The biggest network in the world is the internet!

3. Networking Bus network Bus network is the most straight forward type of network. All of the computers are connected together by a single cable. The cable is known as a bus.

4. Networking Bus network A packet will travel down the bus and be read by the PC it is intended for. The packet will travel past each PC but will be ignored unless the IP address’s match. Packet

5. Networking Collision Packets might be sent by 2 computers at the same time. This could lead to a collision. This would destroy both packets! Packet

6. Networking Bus network – easily broken If the cable breaks then the whole bus network is broken. This means packets can not get to their destination. Packets placed onto a broken bus will be lost. It does not matter where the break in the cable is, all PC’s on the bus will be broken. Packet

7. Networking Activity Copy the bus diagram into your notes and describe – What is a bus network? What are the problems with a bus network?

8. Networking Ring network In a ring network each computer is connected to at least two other computers. Packets will travel in one direction only. A computer can only send packets when it has a token. Ring networks are sometimes referred to a token ring as a result

9. Networking Token past around The token is past around from PC to PC. When a PC gets the token it may transmit packets. Each PC is only allowed to transmit packets for a short amount of time. Packet

10. Networking Ring networks – problems Ring networks never have collisions. However if a cable breaks and the ring is broken then the network will stop working.

11. Networking Activity Copy the ring diagram into your notes and describe – What is a ring network? How does a token work?

12. Networking Star network A star network will have a server or router or switch in the centre of the network. Computers will connect to the server/router/switch. If a single cable breaks the network will still work. However if the server/router/switch breaks the network will go down.

13. Networking Activity Copy the star diagram into your notes and describe – What is a star network?

14. Networking Designing a network Star networks are more reliable. However they are also the most expensive to set up. Bus networks are the cheapest but they do suffer from collisions. When creating a network for a company you must consider – The amount of money available The reliability needed The speed needed It is very common to mix topologies together.

15. Networking example network Star networks are more reliable. However they are also the most expensive to set up. Bus networks are the cheapest but they do suffer from collisions. When creating a network for a company you must consider – The amount of money available The reliability needed The speed needed It is very common to mix topologies together. Note – Hubs act like a bus network. The cable is inside the hub and will connect all of the devices using a bus topology.

16. Networking example network This example has a router at the centre. It uses a star topology to connect two bus networks together. This means that if one bus fails the rest of the network will still work. The server is always connected to the router.

17. Networking Homework Activity Using Publisher/Word: create an example of the following networks – Ring network Star network A combination of star and bus network. Use a range of devices in your diagram: Switch / Hub / Router Desktop PC / Laptop / Server Networked Printer Print screen once done and add to your revision notes.