Network topologies, protocols and layers - AQAStar networks

Star topologies are used in many networks, large and small.

In a star topology, all nodes indirectly connect to each other through one or more switches. The switch acts as a central point through which all communications are passed.

Large networks using a star topology are usually controlled by one or more servers. Even though no single computer controls the network, all communications still pass through the central switch.

Advantages and disadvantages of using a star topology

Having nodes arranged in a star topology brings some benefits:

• each node is separately connected, therefore a failure of one node or its link - transmission media - does not affect any other nodes
• new nodes can be added to the network simply by connecting them to the switch
• star networks tend to have higher performance as a message is passed on to its intended node only

However, star topologies also have their disadvantages:

• the whole network fails if the switch fails as no node can communicate
• a wired star topology requires plenty of cable - in a large network this can be expensive

Star topologies tend to be found in large organisations where high performance is a must.

They are also found in home networks, especially those that are wireless. In the example below, a router with a wireless access point (WAP) provides the central connection for all nodes.