Topologies Flashcards
name 4 Network topologies
Bus
Ring
Star
Mesh
Explain Bus topology
Consist of a single cable/one shared link to which each network device is connected
There is no direct connection between any pair of end-systems
A message must therefore be broadcast even though it might only be intended for one end-system
There is a terminator at the end of each cable to absorb signals that have reached the end of the cable and therefore prevents these signals from bouncing back and causing interference
What are the advantages of Bus topology
Relatively cheap to install since only 1 cable is needed
Easy to add network devices
Disadvantages of Bus topology
Whole network can fail if the cable is damaged
Can be difficult to identify where a fault is on the cable
High network traffic when more devices are added degrades the performance0 only message being able to be sent at once and because more collisions happen
Security risk due to Broadcast system- data is received by all devices on the network
Explain Ring topology
A network in which the cable connects one network device to another in a closed loop or ring
Each network device can be though of as a ‘in’ and an ‘out’ connection
All message travel in the same direction so there are no collisions
What are the advantages of ring topology
Adding extra devices doesnt affect the performance of the network
Easy to add network devices
What are the disadvantages of ring topology
Whole network will fail if the cable is damaged or a device on the network fails
Adding devices shuts down the network temporarily as the devices are in a loop
Can be difficult to identify a fault in the network
More expensive than bus topology as more cable is needed
Explain Star topology
Each network device is connected to a central device- a hub or a switch
Hub is broadcast and switch is multicast or unicast
What are the advantages of star topology
A damaged cable will not stop the whole network from working, just the network device connected to it
If a switch is used, then the network is efficient as messages are only sent to devices needing them. This also adds to security as not all devices will see a message
Easy to locate faults as they will normally only involve 1 device
A new device can be added or removed without disturbing the rest
What are the disadvantages of star toplogy
If the central device fails then the whole network will fail
Expensive to install due to amount of cable needed and central device
Explain Mesh topology
Can be fully connected or partially connected
Each device in a mesh network will pass messages to other devices in the network
Can be wired or wireless
What are the advantages of mesh topology
Fault tolerant, as when one device fails, the message can be re-routed
Very high performance because each network device is likely to be connected to multiple other devices
In a wireless mesh network, each node extends the range of the network
What are the disadvantages of mesh topology
Wired mesh networks are expensive and difficult to install and maintain
Hard to maintain due to number of connections within the network
