Star & Mesh Networks (OCR GCSE Computer Science)

A network topology is the physical structure of the network

It defines how the network hardware will be arranged to create the network

Different network models (PS2P/Client-Sever) can be used on a topology

Many different topologies have been used in the world of networking however, there are two popular topologies to understand for the exam

• Star Topology

• Mesh Topology

A star topology has a central switch which all other devices connect to

A switch is an intelligent device which ensures that traffic only goes to the intended device

A star topology is commonly seen in most homes, businesses, organisations and schools

If any single cable stops working, the rest of the network will continue to work

• An example you may have experienced would be in school when one computer won't log on to the network, but all other classmates can get logged on

This is important because in other topologies if a cable was broken, all computers on the network would stop working which would have a negative impact on learning in schools and businesses completing their daily tasks

The central switch is a single point of failure

This means that if the switch stops working, all of the devices connected to it will not be able to connect to the network or any of its facilities and resources

A mesh topology allows all computers to be connected to all other computers

This is known as a full mesh network topology

LANs can make use of mesh networks however, they are more commonly seen in IoT devices such as wearable technology and smart home devices

If any single cable stops working, the rest of the network will continue to work as the data can find a different route to get to its destination

In the example below you can see that one cable has been marked as not working and that that data can simply use an alternate route

The topology requires a lot of hardware, cables and switches to set up

This means there is a higher cost for setting up the network

Adding new devices is not as easy as in a star topology, making it more challenging to scale the network

The solution to these disadvantages is called a ‘Partial Mesh Topology’

A partial mesh topology is very similar to a full mesh, with the difference being that each device is not connected to every other device directly

This means 

• Less cables and hardware are required

• Multiple routes still exist between devices

• It is a compromise solution to reduce the amount of hardware needed

The diagram below is an example of how the backbone structure of the Internet appears