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
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
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
A star topology can be made by connecting bus topology. The backbone
of bus topology is connected to the central hub.