Star topology
A 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 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 union of these network devices to the central component is represented visually in a star-like fashion.
All data traffic comes from the center of the star. So this central site has control of all the nodes connected to it. The central hub is usually a fast, independent computer and is responsible for routing all traffic to the other nodes.
The node at the center of the network acts as a server and peripheral devices act as clients.
Features of Star topology
In 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 out 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 like a server, controlling and managing all network functions.
If the nodes want to communicate, they transmit the message to the server and forward this message to the other nodes. Therefore, they form a topology like the representation of a star.
different implementations
Star topologies can be implemented with wired Ethernet backbones, wireless routers, and/or other components. In many cases, the server is the central hub and the additional nodes are the clients.
Depending on the network card used by each computer, either an RJ-45 network cable or a coaxial cable is used to connect the devices.
Generally, the star topology is coupled with a bus network. This is done by connecting the hub to the backbone of the bus. This composition is called a tree network.
Communication
Assume that all 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 in the switch memory.
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 check the address of the destination computer and 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 announces, “I advertise to all ports connected to me that I have a packet for this address. Who among you owns this address?
This procedure is called ARP (Address Resolution Protocol). Using this network protocol, the hub can find the address of the desired computer. In this way, you transfer the package to the target machine.
Advantages of Star topology
Limit the impact of crashes
The main advantage of a star network is to limit the impact of a failure. When a computer on the network malfunctions, it does not affect the rest of the network, it only affects the local range of that computer. The network will continue to function normally.
For the same reason as above, this topology makes it possible to add, replace, or delete any individual component to and from the network. Therefore, it is easy to extend the network without interrupting its operation.
centralized management
Network management is centralized through the use of a central computer, hub or switch.
All computers depend on the central device. Invariably, this means that any problem that leaves the network down can be traced back to the central hub.
Easy administration and maintenance
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 in terms of functionality.
Problems are easy to pinpoint because a single cable failure will only affect a single user.
Higher performance and security
Data packets do not need to pass through multiple nodes. The fact that there is no data collision increases its performance, making data transfer considerably faster.
Furthermore, the fact that data packets only have to pass through a maximum of three different points (computer A – hub – computer B) ensures that the data is secure.
Disadvantages of Star topology
Core device dependency
The main problem with the star network topology is that it relies heavily on the operation of the central device.
If the hub, switch, or central server fails, the entire network will be dropped 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 does the size and therefore the required infrastructure.
Higher implementation cost
It may have a higher cost of implementation, especially as a switch or hub is additionally used as the central network connection device.
More cables are needed to connect compared to ring and bus topology because each computer must be connected individually to the central server. Thus, the expenses incurred in the star topology will also be relatively high.
Bottlenecks
This type of network can be vulnerable to bottleneck issues. If one of the nodes uses a significant part of the central hub’s processing power, this will be reflected in the performance of other nodes.
The performance of the entire network directly depends on the performance of the hub. If the server is slow, the entire network will be slower.
If the central hub is compromised in any way, it leaves the entire network vulnerable.
