The star topology or star network is a configuration for a local area network (LAN) in which each of the nodes is connected to a central connection point, such as a hub, switch or a computer. This topology is one of the most common network configurations.
Therefore, it is a network topology in which each individual part of the network is connected to a central node. The attachment of these network devices to the core component is visually represented similar to a star.
All data traffic comes from the center of the star. Thus, this central site has control of all nodes connected to it. The central hub is usually a fast and independent computer and is responsible for routing all traffic to the other nodes.
The node in the center of the network works as a server and the peripheral devices act as clients.
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In the star topology, there is a point-to-point connection between each node and a hub device. Therefore, each computer is individually connected to the central server..
Its design resembles a bicycle wheel with the spokes spreading from the center. Thus, data exchange can only be done indirectly through the central node to which the other nodes are connected..
The central device receives a data packet from any node and passes it on to all other nodes on the network. The hub works as a server, controlling and managing all network functions.
If the nodes wish to communicate, they transmit the message to the server and this forwards said message to the other nodes. Therefore, they form a topology like the representation of a star.
Star topologies can be implemented with wired Ethernet fabrics, wireless routers, and / or other components. In many cases, the server is the central hub and the additional nodes are the clients.
According to the network card that each computer uses, to connect the devices together, an RJ-45 network cable or a coaxial cable is used..
The star topology is often coupled with a bus network. This is done by connecting the hub to the bus backbone. This composition is called a tree network.
Suppose all the computers on a floor are connected to a common hub or switch. In this case the switch maintains a CAM (Content Addressable Memory) table.
This CAM table is a content addressable memory, where the hardware addresses of all connected devices are stored within the memory of the switch..
For example, if computer A wants to send a data packet to computer B, computer A will send the message to the switch. The switch will verify the address of the destination computer and thus forward the message to it..
In the case of a hub, it does not have its own memory. When computer A sends a message to computer B, the hub alerts: “I announce to all ports connected to me that I have a packet for this address. Who of you owns this address? "
This procedure is called ARP (Address Resolution Protocol). Using this network protocol the hub can find the desired computer address. In this way it transfers the packet to the destination machine.
The main advantage of a star network is to limit the impact of a fault. When any computer on the network is not working properly it will not affect the rest of the network, but will only affect the local range of that computer. The network will continue to function normally.
For the same reason above, this topology makes it easy to add, replace, or remove any individual component to and from the network. Therefore, the network is easy to extend without having to interrupt its operation..
Network management is centralized, through the use of a central computer, hub or switch.
All computers depend on the central device. This invariably means that any problems that render the network inoperable can be traced back to the central hub..
It is very easy to manage and maintain the network, because each node only requires a separate cable. It is the simplest of all topologies when it comes to functionality.
Problems are easy to locate, because the failure of one cable will affect only one user.
Data packets do not have to traverse multiple nodes. The fact that there is no data collision increases its performance by making data transfer considerably faster.
Furthermore, the fact that the data packets only have to pass through a maximum of three different points (computer A-hub-computer B) guarantees that the data is secure..
The main problem with the star network topology is the fact that it is highly dependent on the operation of the central device.
If the hub, switch, or core server fails, the entire network will go down and all computers will be disconnected from the network.
The central device of the network is the one that determines the total number of nodes that the network can handle. The size of the network will depend on how many connections can be made to the hub. As the number of connections increases, so will the size and therefore the infrastructure required.
May have a higher cost of implementation, especially since a switch or hub is additionally used as the central network connection device.
More cables are required to connect compared to the ring and bus topology, because each computer must be individually connected to the central server. Thus, the expenses incurred in the star topology will also be relatively high..
This type of network can be vulnerable to bottleneck problems. If one of the nodes uses a significant part of the central hub's processing capacity, it will be reflected in the performance of other nodes.
The performance of the entire network is directly dependent on the performance of the hub. If the server is slow it will cause the whole network to slow down.
If the central hub is compromised in any way, it will leave the entire network vulnerable.
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