Network topology is the arrangement of computer devices in computer network to establish communication among them. It defines a layout of a network that means it determines how different nodes are connected and communicated together within a network. Network topology can be according to logical aspect or on physical aspect. Physical topology describes placement of different components of the network while logical topology describes the data flow within a network instead of physical design.
Network topology can be categorize in 2 main categories on the basis of connection:
Point-to-point: a dedicated link between two devices.
Multipoint: More than two specific devices share a single link.
Multipoint Topology: Multipoint topology is based on “sharing”. In this type of topology, each node on a network has only one connection. Bus Topology is a common example of Multipoint Topology.
Network topology types
Topology in networking can mainly be divided into 4 different network topologies: Mesh topology, bus network topology, star topology and ring topology. Hybrid topology is also common.
This topology is point-to-point connection topology where each node is connected with every other nodes via cables. It is a dedicated point to point connection where the link carries traffic between the two devices that are connected. Total number of duplex links required in a mesh topology is n (n-1) where n represents total number of nodes in the topology.
It eliminates data traffic problems, it is the most reliable and robust topology. This topology maintain highest level of privacy and security. Its point-to-point connection gives advantage to easily find out errors and isolate it.
It is very expensive topology. Because of complex connection it is very difficult to add a new device in the network.
Practical implementation of mesh topology can be seen in telephone regional offices where each regional office needs to be connected with every other regional office.
This topology is a multipoint connection topology where one long cable connects all the nodes in a network. Every node is linked with the network via a tap and a drop line. Drop line is the connection between main cable and the node while Tap is the connector. This topology can connect limited number of nodes.
Bus topology provides easy installation facility. It require very less cable than other topologies hence not so expensive.
Bus topology includes difficult reconnection and fault isolation. Signal reflection at taps can cause quality degradation. A fault in the main cable can cause the failure of the whole network.
This topology is a point-to-point connection topology where each node is dedicatedly connected to the hub. Hub is the central controller that connects all the devices in the network. The devices are not connected directly in this topology. When a node send data to other it is firstly received by hub then it is transmitted to the receiver.
Star topology is less expensive than Mesh topology. Installation and reconfiguration is easy in this topology. This topology is robust and reliable. If one link fails to work then the whole network doesn’t get affected, it stops the working of that particular node instead. It is easy to detect and isolate fault in this topology.
The main problem in this topology is that the whole topology is dependent on a single point called hub if the hub goes down, the whole network is dead.
It is a dedicated point-to-point connection where each node is connected with exactly two nodes, its previous node and its next node in the network. All messages travel through a ring in the same direction (either “clockwise” or “counterclockwise”) till the destination node receives it. It is a closed loop configuration.
Ring topology is cheap to implement. It doesn’t get affected by high traffic or adding more nodes.
Adding or removing a node disturb the activity of the whole network. If any node stop working, the whole network becomes inactive. Troubleshooting is very difficult in ring topology.
Hybrid topology is a mixture of two or more topologies. It inherits the pros and cons of all using topologies in the network.
Hybrid topologies are reliable. Error detection and correction is easy in such networks. These are effective and flexible topologies that can easily be scaled according to the size of area.
Hybrid topology is complex in design. This kind of network topology is expensive.