Have you ever gave a thought about why our streets or roads and maps are designed in a particular way? Of course, for our convenience. How do you say it is convenient? When it is an efficient path, shorter and describable. So in the same way the paths are, networks are connected, more specifically networking devices are connected in a particular shape or relation. Hence, the way a network is arranged, including the physical or logical description of how links and nodes are set up to relate to each other is known as Network Topology!

There isn’t the only way to make the design. There are numerous ways to arrange the network with its own advantages and disadvantages. According to the requirement and the complexity of the communications different structures are chosen. Here are some network topologies.

Bus Topology

In this topology, all the devices are connected to a single cable that runs in a single direction. This is why it is also referred to as “ line/linear topology or backbone topology “. The devices are connected via drop lines. Since the data will be transmitted through a single cable and in a single direction, there will be a limitation in the length of the cable and also the number of drop lines. The drop lines are connected to the cable via a device called tap.

Advantages:

• It is cost-effective and can be installed easily.
• The requirement for cables is low, i.e. less complex.
• Feasible for smaller networks.

Disadvantages:

• On a larger network, if the main cable has vulnerabilities and a fault occurs, the whole network will be taken down.
• The repair cost is high.
• Since the data flow can’t be bidirectional i.e. half-duplex, this topology is not preferable on networks with higher traffic.
• It is slower compared to ring topology that we will see a little down.

Star Topology

Yes! From the term itself, we can interpret that the structure symbolizes a star. It is the most commonly used network topology. It is laid in such a way that all the nodes in the network will be connected to a single device called Hub. Direct data transmission cannot be done between two nodes or devices. If the communication has to be done between the devices or nodes, the data should transmit via the hub. The hub is a multiport repeater that helps in the prevention of data loss.

Advantages:

• If a single node is faulty, the network won’t we collapsed i.e. robust.
• The addition of devices made easy without disturbing the network.
• Installation is easy.
• The identification of errors is easy as the structure is simpler.

Disadvantages:

• On the flip-side, if the central hub is damaged then the network will be taken down. But if proper maintenance is done by the system administrator, this doesn’t happen often.
• The bandwidth and the speed of the network are determined by the configuration and technical aspects of the central hub.
• Requires higher maintenance.

Mesh Topology

The connection is messy as the name suggests. In this topology, each device is interconnected to each other through a dedicated point. When we name it dedicated it means that the link only carries the information between the two endpoints. Mesh networks can be partial or full. In the partial mesh case, the nodes are interconnected but only to two or three connections whereas for the full mesh topology there is complete interconnection. There are two techniques to transmit data over mesh topology. They are:

1. Mesh Topology: Routing: In this technique, the nodes have a routing logic. The logic is to direct the data in the shortest path possible to the destination. It also has information about the broken links, and it avoids those nodes and re-configure the failed nodes.
2. Mesh Topology: Flooding: It doesn’t have any routing logic. The data is transmitted to all the nodes even if it is not necessary. It floods the network with unwanted data transfer as well.

If there are n devices in the network then each device must be connected with (n-1) devices of the network. The number of links in a mesh topology of n devices would be n(n-1)/2.

Advantages:

• It is the most reliable and stable.
• Because of the complexity of the connection, there are lesser chances of failure.
• It is robust, that is if one connection goes down then the network will not get collapsed.
• Fault detection is easy.
• It provides high security.

Disadvantages:

• Installation and configuring is complex.
• It requires more cabling which limits the no.of devices connected.
• The cost is higher to setup.

Ring Topology

As the name depicts that the topology is connected in a ring or circular network. Each device has two adjacent devices that are connected to it. If a device wants to send data to another device then it sends the data in one direction, each device in ring topology has a repeater, if the received data is intended for other devices then the repeater forwards this data until the intended device receives it. It is half-duplex meaning that the data flow is unidirectional. To make it full-duplex, the addition of the second connection between the network devices works. This is called Dual Ring Topology. It is more efficient and secured.

Advantages:

• Higher traffic will not affect the network.
• Installation is cheap and flexible.
• Since only one device is allowed to transmit the data, there will be no collisions.
• If there is a large network setup in a ring topology, there are repeaters to minimize the data loss and reach the destination.

Disadvantages:

• Fault detection or troubleshooting is hard as the whole network has to be taken down.
• Since all the devices share same bandwidth, addition of devices will contribute to the delays of communication.
• The failure of one device would collapse the complete network.

Hybrid Topology

It is a combination of two or more network topologies. For example, in an industry, one department will be connected in a star topology and the other in a ring topology. The connection between these two topologies results in a hybrid topology.

Advantages:

• It is more reliable and troubleshooting is easy.
• It is flexible and scalable.

Disadvantages:

• Installation is complex.
• Maintenance is high.

Tree Topology

It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy. Each node in a star topology is directly connected to the central hub, a tree topology has a parent-child hierarchy to how the nodes are connected. Those connected to the central hub are connected linearly to other nodes, so two connected nodes only share one mutual connection.

Advantages:

• Expansion of network is easy.
• Fault detection is easier.
• Maintenance is not much higher.

Disadvantages:

• Complexity is high.
• Failure of the central hub collapses the network.
• Installation is costly.

Which network topology is best for you?

No network topology is perfect, or even inherently better than the others, so determining the right structure for your business will depend on the needs and size of your network. Here are the key elements to consider:

• Length of cable needed
• Cable type
• Cost
• Scalability: Whether the system can be expandable or not.

References:

• Cables
• Networking Devices

So, that’s all about Network topologies. If any queries or reviews, feel free to contact us! Have a safe and healthy learning!

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