4.3.1 - Networks - Network Topologies
- Created by: Annie
- Created on: 07-05-13 19:16
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- Network Topologies
- Star
- What is it?
- The switch manages and controls all functions of the network
- It also acts as a repeater for the data flow to maintain signal strength
- Data passes through the switch/hub before continuing to its destination
- A star topology is designed with each node (tile server, workstations and peripherals) connected directly to a central network, switch or hub
- The switch manages and controls all functions of the network
- Advantages
- If one cable fails, the other stations are not affected
- Consistent performance even under heavy use
- Reliable market proven system
- Few problems with data collision since each station has its own cable to the server
- Security can be implemented in the hub/swith
- Disadvantages
- May be costly to install because of the cable lengths required
- The speed of the network is dependent on the quality of the switch/hub
- If the central hub/switch fails, the whole network goes down
- What is it?
- Ring
- What is it?
- Connects computers on a single circle of cable
- No terminated ends
- Signals travel around the loop in one direction and pass through each computer, which can act as a repeater to boost the signal and send it on to the next computer
- It is a Peer to Peer network
- One method of transmitting data around a ring is called Token Passing
- The Token is passed from computer to computer until it gets to a computer that has data to send
- The data is read by each computer until it reaches the computer with the destination address
- The receiving computer returns a message to the sending computer indicating that the data has been received
- After verification, the sending computer creates a new token and releases it on the network
- The receiving computer returns a message to the sending computer indicating that the data has been received
- The data is read by each computer until it reaches the computer with the destination address
- The Token is passed from computer to computer until it gets to a computer that has data to send
- Connects computers on a single circle of cable
- Advantages
- High data transmission rates are possible
- Transmission around the network is one way only
- Each computer has the same level of access, so no one PC can dominate communications
- No dependence on a central computer or file server... each node controls communication to and from itself
- Disadvantages
- If one node breaks down or a cable is broken, the data transmission fails
- To add new devices to the network, all activity must cease until the work is finished
- Faults in the cable are difficult to locate
- If used over large distances, a repeater is required because of degradation of signal
- Over a large distance, the amount of cable required is greater
- What is it?
- Bus/Ethernet
- What is it?
- All the devices on the network (server, PCs, printers etc) are connected by a common main cable
- Data flows in both directions on the cable
- Terminators are used at either end to "absorb" unused communications
- Advantages
- Inexpensive to install as it requires the least amount of cable
- Easy to add more stations without disrupting the network but there is a limit to the number of stations
- Easy to install as it requires just a single main run of cable
- Disadvantages
- Information can be transmitted in either direction and occasionally there is data collision
- Network performance degrades under a heavy load
- 12+ is considered a heavy load
- Can't remove the cables or change calbles
- Any changes will disrupt the network
- Cable failure is difficult to isolate without the correct equipment
- If the main cable breaks, the whole system goes down
- What is it?
- "The way in which the network is constructed"
- Star
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