Star topology is a point to point connection in which all the nodes are connected to each other through a central computer, switch or hub. The central computer, switch or hub is also known as a server while the nodes that are connected are known as clients. In star topology nodes are indirectly connected to each other through a central hub.
Nodes in a star topology are also known as hosts. The cables that are used to connect nodes include optical fibre, twisted pair cable, RJ-45 or coaxial cable. The central device or computer is responsible for controlling and guiding all the traffic in the network.
The performance of the network is dependent upon the capacity of the central computer, switch or hub. If the central device cannot handle more nodes then new nodes cannot be added to the network. The physical appearance of nodes and hubs looks like a star so it is called star topology.
New nodes can be added and removed from the network without affecting any other nodes. Star topology can handle a large amount of data and works well in a large network.
The central hub which connects nodes are of four types:-
- Hub or repeater
- Switch or bridge
- Router or gateway
- Computer
If any host wants to transfer message to any other host then the message is first transferred to central server i.e. hub, switch, router and then passed to the target host. The central host can also be another computer that behaves as a server.
Each node (computer) in the network has some unique address that is used to send and receive a message in the network. Suppose switch is behaving as the server. Switch stores all the addresses of the nodes attached to it. When any node wants to send a message to another node then switch knows which node to send a message to as it has a copy of all the addresses. But if the hub is behaving as the server then hub cannot store addresses so the hub will broadcast message to all the nodes and the target machine will detect the address and receives the message.
If any node in the network gets the bug and stop working then it will not affect other nodes but if the central hub fails then network stop working.
To add a new node to the network only additional cables are required which make it inexpensive but star topology is expensive than a bus topology. Also, server i.e. hub, switch, the router is expensive in cost in the star topology.
A star topology can be made by connecting bus topology. The backbone of bus topology is connected to the central hub.
Example of star topology:
- Ethernet network is made by a star topology