What Is Topology? Advantages And Disadvantages Of Topologies And How Many Types Of Topology

What is Topology?

• Topology defines the structure of the network of how all the components are interconnected to each other. There are two types of topology: physical and logical topology. 

Types of Network Topology

• Bus Topology
• Ring Topology
• Tree Topology
• Star Topology
• Mesh Topology
• Hybrid Topology

Bus Topology

• The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable. 
• Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable.
• When a node wants to send a message over the network, it puts a message over the network. All the stations available in the network will receive the message whether it has been addressed or not. 

Advantages of Bus Topology

• Low-cost cable: In bus topology, nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low.

Disadvantages of Bus Topology

• Extensive cabling: A bus topology is quite simpler, but still it requires a lot of cabling. 

Ring Topology

• Ring topology is like a bus topology, but with connected ends.
• The node that receives the message from the previous computer will retransmit to the next node.
• The data flows in one direction, i.e., it is unidirectional.
• The data flows in a single loop continuously known as an endless loop.
• It has no terminated ends, i.e., each node is connected to other node and having no termination point. The data in a ring topology flow in a clockwise direction. 

Advantages of Ring Topology

• Network management: Faulty devices can be removed from the network without bringing the network down. 
• Product availability: Many hardware and software tools for network operation and monitoring are available. 

Disadvantages of Ring Topology

• Difficult troubleshooting: It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
• Failure: The breakdown in one station leads to the failure of the overall network. 

Star Topology

• Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer.
• The central computer is known as a server, and the peripheral devices attached to the server are known as clients. 

Advantages of Star Topology

• Network control: Complex network control features can be easily implemented in the star topology. Any changes made in the star topology are automatically accommodated.
• Limited failure: As each station is connected to the central hub with its own cable, therefore failure in one cable will not affect the entire network.

Disadvantages of Star Topology

• A Central point of failure: If the central hub or switch goes down, then all the connected nodes will not be able to communicate with each other.
• Cable: Sometimes cable routing becomes difficult when a significant amount of routing is required. 

Tree Topology

• Tree topology combines the characteristics of bus topology and star topology.
• A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion.
• The top-most node in tree topology is known as a root node, and all other nodes are the descendants of the root node.
• There is only one path exists between two nodes for the data transmission. Thus, it forms a parent-child hierarchy. 

Advantages of Tree Topology

• Easily expandable: We can add the new device to the existing network. Therefore, we can say that tree topology is easily expandable.

Disadvantages of Tree Topology

• High cost: Devices required for broadband transmission are very costly.
• Failure: A tree topology mainly relies on main bus cable and failure in main bus cable will damage the overall network. 

Mesh Topology

• Mesh technology is an arrangement of the network in which computers are interconnected with each other through various redundant connections.
• There are multiple paths from one computer to another computer.
• It does not contain the switch, hub or any central computer which acts as a central point of communication.
• The Internet is an example of the mesh topology.
• Mesh topology is mainly used for WAN implementations where communication failures are a critical concern. 

Advantages of Mesh Topology

• Reliable: The mesh topology networks are very reliable as if any link breakdown will not affect the communication between connected computers.
• Fast Communication: Communication is very fast between the nodes.

Disadvantages of Mesh Topology

Cost: A mesh topology contains a large number of connected devices such as a router and more transmission media than other topologies.

Management: Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected. 

Hybrid Topology

• The combination of various different topologies is known as Hybrid topology.
• A Hybrid topology is a connection between different links and nodes to transfer the data.
• When two or more different topologies are combined together is termed as Hybrid topology and if similar topologies are connected with each other will not result in Hybrid topology. For example, if there exist a ring topology in one branch of ICICI bank and bus topology in another branch of ICICI bank, connecting these two topologies will result in Hybrid topology. 

Advantages of Hybrid Topology

• Reliable: If a fault occurs in any part of the network will not affect the functioning of the rest of the network.
• Scalable: Size of the network can be easily expanded by adding new devices without affecting the functionality of the existing network.

Disadvantages of Hybrid Topology

Complex design: The major drawback of the Hybrid topology is the design of the Hybrid network. It is very difficult to design the architecture of the Hybrid network.

Costly Hub: The Hubs used in the Hybrid topology are very expensive as these hubs are different from usual Hubs used in other topologies.