Star Topology is usually used in a LAN environment; the whole topology is managed by a centralized device network switch or hub. In this topology, all nodes like user computers, printers, and servers are directly connected with a centralized network switch or hub. Every single node whatever is connected with it has its own dedicated link which connects it with a network switch. No one else can reach the node without passing through a network switch. A twisted pair cable with RJ45 connectors at its both end is used to connect the node with a network switch. Because of its working nature and connectivity style as all user devices connect with centralized devices this topology is also referred to as hub and spoke topology.
In this topology, all the connected devices can communicate with each other indirectly using the centralized device. Have a look at the diagram which is showing the star topology that how it will connect all the nodes with a centralized network switch or hub. Computers and printers are showing as end-user devices, a centralized network switch and lines that are interconnecting the devices with network switch are denoting the UTP twisted pair cable and RJ45 connector which will terminate the cable at both ends at user computer side and network switch side.
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| RJ 45 Connector |
Now we will move to the next part of our discussion that how this topology actually works, the detailed process when a user computer sends a data message to the other connected user computer or a printer.
Patched UTP cable
Before going into detail about the process I want to mention the answer to a question people usually ask that can we use the star topology to connect the wireless peripherals? the answer is yes, in the star topology connection could be wired or wireless depends on centralized devices what is support.
OK now move back to our process in detail that how star topology works. As we mentioned a lot of time in our discussion that in this topology a centralized device which could be a network switch or hub is completely responsible to control the data communication between all nodes.
There are different ways that how central devices manage the communications of devices depends on the working capability of the central device. In the early days, an Ethernet hub was being used as a central device the Ethernet hub was not so efficient it just listened to the message comes from a user's computer and retransmit or also broadcast to all its connected user's computers. It was a simple network hub just listen to the message and repeat it to all connected computers. Because of its broadcasting nature, all the messages which were coming to the central hub were being broadcast to all connected devices instead of the only intended one. Due to the broadcasting nature whole topology works slow as too many much-connected devices were sending data messages to a central hub for specific user computers but the hub retransmits these all messages to all connected devices. The Ethernet hub was also being placed physically in the center of the network as it looks like a real star, but the process which was being done by this device was like the process of old traditional bus topology.
Now here comes the network Ethernet switch which looks exactly like the Ethernet hub physically but works more efficiently and in a different way as compare to the Ethernet hub. As Ethernet hub generates broadcast messages to communicate with its connected devices, on the other hand, Ethernet switch eliminates the use of broadcast it creates the Physical address also called MAC (Media Access control) address table in which it maps the physical address of user device whatever it is, like computer or printer to the port of Ethernet switch it is connected with. When the Ethernet switch received a data message from any user device for a specific device it just checks its MAC table finds the destination address in it and forwards the received data message to that device instead of broadcasting to all connected devices. In this way, the whole job is done by Ethernet switch more efficiently and securely as data is only being transfer to the relevant devices not to all. The network is not being slow because the broadcast is also being eliminated.
In the star topology if one link between the user device and the Ethernet switch is damaged it will not affect the whole topology all other devices will keep continue their work normally only the thing is that other devices will not communicate with that failed devices till the time its link restores. But again there could a critical condition if the Ethernet switch failed or did not work properly because of hardware issues or configuration or IOS problems we will discuss in detail in the future. So here is the deal The network redundancy comes into play a Mesh topology we will be discussed in detail in a separate post.