1. NETWORKS Network Topologies / Configurations

2. Learning Objectives Describe for each type of network topology the relative strengths and weaknesses.

3. Network Topologies / Configurations Networks can have their computers connected in a number of different ways. Networks can have their computers connected in a number of different ways. Each method has its advantages and disadvantages.

4. BUS Advantage: Simple and cheap to set up. Out of all the topologies the bus topology uses the least cabling.Disadvantages: If there is a break in the main cable, the entire network stops working and for this reason adding workstations disrupts the entire network (there needs to be a terminator on both ends of the cable for it to work). A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). Data trying to travel simultaneously along the cable in different directions is called a 'data collision'. Poor security as messages do not have to go through the server. Workstation terminator

5. RINGAdvantage: If there is a break in the cable, the network will continue to operate because the messages can go in the other direction. If there is a break in the cable, the network will continue to operate because the messages can go in the other direction. The workstations themselves now act as terminators. Simple and cheap to set up as cabling is minimal (more than Bus but less than Star). Simple and cheap to set up as cabling is minimal (more than Bus but less than Star). One direction is chosen for data transmission (changed only if cable is broken as explained above) so data collisions are prevented. One direction is chosen for data transmission (changed only if cable is broken as explained above) so data collisions are prevented. Performs better than any other topology under heavy network traffic (load). Performs better than any other topology under heavy network traffic (load). Can be used for wide area networks. Can be used for wide area networks. Disadvantage: Adding workstations does not stop the network but messages have to go the other way so the network traffic is slowed. Adding workstations does not stop the network but messages have to go the other way so the network traffic is slowed. Poor security as messages do not have to go through the server. Poor security as messages do not have to go through the server. Workstation Server Workstation

6. STARAdvantage: Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Good data security - no workstation can interact with another without going through the server first. Good data security - no workstation can interact with another without going through the server first.Disadvantage: Complex wiring - lots of cables required. Complex wiring - lots of cables required. Extra hardware required such as hubs (or switches see right). Extra hardware required such as hubs (or switches see right). Workstation Server Workstation Notes: 1.A STAR network dictates that all messages travel via the server on their way to their destination. 2.If the central point is a ‘switch’ instead of a ‘hub’ then data collisions are prevented as the switch controls communications (a hub however just relays all communications so data collisions can still occur). 3.If the hub breaks down or the cable hub server breaks then the whole network goes down.

7. Peripherals Printers, scanners etc…. are often known as peripherals and are often shared by connecting them to the server, rather than directly to the network as shown in previous diagrams.

8. Comparing Topologies When asked to compare topologies do not use an advantage or disadvantage if they also apply to the other/s.

9. Bus: Advantage: Advantage: Simple and cheap to set up. Out of all the topologies the bus topology uses the least cabling. Disadvantages: Disadvantages: If there is a break in the main cable, the entire network stops working. A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). Ring: Advantage: Advantage: Performs better than any other topology under heavy network traffic (load). If there is a break in the cable, the network will continue to operate because the messages can go in the other direction. One direction is chosen for data transmission (changed only if cable is broken as explained above) so data collisions are prevented. Can be used for wide area networks. Disadvantage: Disadvantage: Slightly more difficult to set up than the BUS topology and if one workstation is off or a workstation is added, network traffic is slowed (but not stopped) as messages have to travel in the other direction (one workstation being switched off in a BUS has no affect at all on the network). Bus Vs Ring

10. BUS Vs STAR Bus: Advantage: Advantage: Simple and cheap to set up. Out of all the topologies the bus topology uses the least cabling. Disadvantages: Disadvantages: If there is a break in the main cable, the entire network stops working and for this reason adding workstations disrupts the entire network. A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). Poor security as messages do not have to go through the server. Star: Advantage: Advantage: Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Good data security - no workstation can interact with another without going through the server first. Disadvantage: Disadvantage: Complex wiring - lots of cables required. Extra hardware required such as hubs (or switches).

11. RING Vs STAR RING: Advantage: Advantage: Performs better than any other topology under heavy network traffic (load). Simple and cheap to set up. Less cabling than a STAR network topology. Disadvantages: Disadvantages: Adding workstations does not stop the network but messages have to go the other way so network traffic is slowed. Poor security as messages do not have to go through the server. Star: Advantage: Advantage: Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Good data security - no workstation can interact with another without going through the server first. Disadvantage: Disadvantage: Complex wiring - lots of cables required. Extra hardware required such as hubs (or switches).

12. BUS Vs RING Vs STAR Bus: Advantage: Advantage: Simple and cheap to set up. Out of all the topologies the bus topology uses the least cabling. Disadvantages: Disadvantages: If there is a break in the main cable, the entire network stops working and for this reason adding workstations disrupts the entire network. A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). Ring: Advantage: Advantage: Performs better than any other topology under heavy network traffic (load). Can be used for wide area networks. Breaks in any cables do not stop the network but network traffic is slowed. If the hub breaks down or the cable hub server breaks in a STAR then the whole network goes down. Disadvantage: Disadvantage: Adding workstations does not stop the network but messages have to go the other way so the network traffic is slowed. Star: Advantage: Advantage: Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Good data security - no workstation can interact with another without going through the server first. Disadvantage: Disadvantage: Complex wiring - lots of cables required. Extra hardware required such as hubs (or switches).

13. Plenary Describe each type of network topology and give their relative strengths and weaknesses.

14. BUS Advantage: Simple and cheap to set up. Simple and cheap to set up. Out of all the topologies the bus topology uses the least cabling. Out of all the topologies the bus topology uses the least cabling.Disadvantages: If there is a break in the main cable, the entire network stops working and for this reason adding workstations disrupts the entire network (there needs to be a terminator on both ends of the cable for it to work). If there is a break in the main cable, the entire network stops working and for this reason adding workstations disrupts the entire network (there needs to be a terminator on both ends of the cable for it to work). A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). A busy (many workstations or a lot of traffic) bus network will have many data collisions and so will be VERY slow (slowest network topology). Data trying to travel simultaneously along the cable in different directions is called a 'data collision'. Poor security as messages do not have to go through the server. Poor security as messages do not have to go through the server. Workstation terminator

15. RINGAdvantage: If there is a break in the cable, the network will continue to operate because the messages can go in the other direction. If there is a break in the cable, the network will continue to operate because the messages can go in the other direction. The workstations themselves now act as terminators. Simple and cheap to set up as cabling is minimal (more than Bus but less than Star). Simple and cheap to set up as cabling is minimal (more than Bus but less than Star). One direction is chosen for data transmission (changed only if cable is broken as explained above) so data collisions are prevented. One direction is chosen for data transmission (changed only if cable is broken as explained above) so data collisions are prevented. Performs better than any other topology under heavy network traffic (load). Performs better than any other topology under heavy network traffic (load). Can be used for wide area networks. Can be used for wide area networks. Disadvantage: Adding workstations does not stop the network but messages have to go the other way so the network traffic is slowed. Adding workstations does not stop the network but messages have to go the other way so the network traffic is slowed. Poor security as messages do not have to go through the server. Poor security as messages do not have to go through the server. Workstation Server Workstation

16. STARAdvantage: Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Reliable - new stations may be added / deleted / damaged and cables between workstations and the hub broken without affecting the network at all. Good data security - no workstation can interact with another without going through the server first. Good data security - no workstation can interact with another without going through the server first.Disadvantage: Complex wiring - lots of cables required. Complex wiring - lots of cables required. Extra hardware required such as hubs (or switches see right). Extra hardware required such as hubs (or switches see right). Workstation Server Workstation Notes: 1.A STAR network dictates that all messages travel via the server on their way to their destination. 2.If the central point is a ‘switch’ instead of a ‘hub’ then data collisions are prevented as the switch controls communications (a hub however just relays all communications so data collisions can still occur). 3.If the hub breaks down or the cable hub server breaks then the whole network goes down.