Network Topology | Computer Networks

Topologies are a geometric representation of the relationship of links and linking of devices with one another. Two or more computers connected to each other using cables form a link, and two or more links collectively form a topology.

In computer networks, topologies are mainly categorized into the following types:

1) Mesh topology
2) Star topology
3) Bus Topology
4) Ring Topology
5) Tree Topology
6) Hybrid Topology

Mesh Topology: In mesh topology each device has a dedicated point-to-point link to every other device. Dedicated connection means that cable carries data only between two devices. If N number of devices are connected with each other in the mesh topology then, ports required by each device is N-1, and total number of ports required in the topology is N*(N-1). Total number of dedicated cables required to connect them is NC2, i.e.N(N-1)/2.

Mesh topology is robust and secure. But it is difficult to install and configure the mesh topology and cost is also high as
compared to other topologies.

Star topology: Each device has a dedicated point-to-point link with a central controller, known as a hub. Devices are not linked to one another directly, so each device needs one link and one port to connect with the central hub. If a device wants to send the data to another device, so it will send it to the controller, then it is the responsibility of the hub to transmit the data to the correct destination. If N number of devices are connected in star topology so the number of cables required is N.
Star topology is robust and has easy fault detection and isolation mechanism. But the entire system is dependent on the central
controller, i.e. hub and the cost of installation is high.

Bus Topology: In a bus topology, one long cable is the backbone to connect all the computers in a network. Computers are connected to bus cables by drop lines & taps. A drop line is a connection running between the device & main cable. It is not bidirectional, and has multipoint connection. It is not robust because the entire dependency is on backbone cable.

Ring Topology: Each device has a dedicated point-to-point connection with only two devices on either side of it. The signals are passed along the ring in one direction, from device to device, until it reaches their destination. Signal can be made bidirectional, using two connections between each node. Repeaters are used in ring topology to prevent data loss.This topology is cheap to install and expand and has easy fault isolation mechanism. But it is difficult to troubleshoot the problem in ring topology and it is unidirectional.

Tree Topology: Tree topology has a hierarchical stream of data. Secondary hubs are connected with a central hub that has repeaters. Data flow from top to bottom or vice versa, i.e. from a central hub to devices. More devices can be connected to a central hub easily, it allows network isolation and also prioritizes signals from different devices. But the entire dependency of the system on the central hub.

Hybrid Topology: This topology is a combination of two or more different topologies to make a resultant topology with advantages of basic topologies instead of having the characteristic of only one specific topology. Hybrid topologies are completely reliable, flexible, scalable, has easy fault detection and troubleshooting, it can handle a large network. But it is complex in design and are expensive in cost

Network Topologies: https://www.geeksforgeeks.org/types-of-network-topology/