Network topology is the way that defines the structure of a network, and how all the components are interconnected to each other³. The components of a network can be nodes (such as computers, routers, switches, etc.) or links (such as cables, wireless connections, etc.)¹. Network topology can be classified into two types: physical topology and logical topology¹.

Physical topology is the geometric representation of all the nodes and links in a network¹. It shows how the devices are physically connected and the layout of the cables and wires². Physical topology can affect the performance, reliability, and security of a network². There are six types of physical topology which are:

• Bus topology: All the nodes are connected through a single cable known as a backbone cable¹. The backbone cable acts as a shared medium for data transmission². The bus topology is simple and low-cost, but it has low data speeds and is prone to collisions and network failures¹.

• Ring topology: All the nodes are connected in a circular shape, forming a closed loop¹. Each node receives data from its previous node and sends it to its next node². The ring topology has high data speeds and no collisions, but it requires more cables and is difficult to add or remove nodes¹.

• Star topology: All the nodes are connected to a central device, such as a hub or a switch¹. The central device acts as a controller and manages the data transmission among the nodes². The star topology has high data speeds and reliability, but it requires more cables and is dependent on the central device¹.

• Mesh topology: Every node is connected to every other node via a dedicated link². Each link is a separate channel for data transmission¹. The mesh topology has high data speeds and reliability, but it requires more cables and ports, and is complex to configure and maintain².

• Tree topology: It is a hierarchical structure of nodes, where each level is connected to the higher level by a single link¹. The top level is called the root node, and the lower levels are called branches or sub-trees². The tree topology combines the advantages of bus and star topologies, but it requires more cables and is vulnerable to root node failures¹.

• Hybrid topology: It is a combination of two or more different types of physical topologies¹. For example, a star-ring topology is a hybrid topology where each node in a ring is connected to a central device in a star². The hybrid topology can be customized to suit specific needs, but it is complex and expensive to implement¹.

Logical topology is the way that data flows between the nodes in a network¹. It shows how the devices communicate with each other logically, regardless of their physical connections². Logical topology can be different from physical topology depending on the network protocols and media access methods used by the devices³. For example, in a bus physical topology, the logical topology can be either broadcast or token passing, depending on whether the devices use CSMA/CD or token ring protocols respectively².

The choice of network topology depends on various factors, such as the size, scope, purpose, cost, performance, and scalability of the network. Different types of network topologies have different advantages and disadvantages, and they suit different kinds of applications and scenarios. Therefore, network designers should consider these factors carefully before selecting an appropriate network topology for their needs.