8 junio, 2024

Star topology: characteristics, advantages, disadvantages

The star topology or star network is a setup for a local area network (LAN) in which each node 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 junction 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 the nodes connected to it. The central hub is usually a fast, stand-alone 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.

[toc]

Characteristics

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 out from the center. Thus, data exchange can only take place indirectly via 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 concentrator works like a server, controlling and managing all the functions of the network.

If the nodes want to communicate, they transmit the message to the server and it forwards said 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 fabrics, 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 that each computer uses, an RJ-45 network cable or a coaxial cable is used to connect the devices together.

Often the star topology is coupled with a bus network. This is done by connecting the hub to the bus backbone. This composition is called a tree network.

Communication

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 switch’s 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 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 says: “I announce to all ports connected to me that I have a packet for this address. Which of 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. This way it transfers the packet to the destination machine.

Advantages

Limit failure impact

The main advantage of a star network is to limit the impact of a failure. When any computer in the network is not working properly, it will not affect the rest of the network, it will only affect the local range of that computer. The network will continue to function normally.

For the same reason as 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.

centralized management

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 issues that render the network inoperable 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 locate, because a cable failure will affect only one user.

Increased performance and security

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.

In addition, 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.

Disadvantages

Central device dependency

The main problem with the star network topology is the fact that it is highly dependent on the performance of the central device.

If the hub, switch, or central 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 required infrastructure.

Higher cost of implementation

It 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 costs incurred in the star topology will also be relatively high.

Bottleneck

This type of network can be vulnerable to bottleneck problems. If one of the nodes uses a significant part of the processing capacity of the central hub, 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.

References

TelecomABC (2019). Star topology. Taken from: telecomabc.com. ComputerHope (2018). Star topology. Taken from: computerhope.com. Techopedia (2019). Star Topology. Taken from: techopedia.com. Loving Shekhar (2016). What Is Star Topology? Advantages And Disadvantages of a Star Topology. Fossbytes. Taken from: fossbytes.com. Techspirited (2019). Star Topology. Taken from: techspirited.com.

Deja una respuesta

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *