Network Topology:

Topology refers to arrangement of the nodes in the network. Topology is the geometrical representation of linking devices (usually called nodes) to each other in LAN. Possible topologies which are being used are mesh, bus, star, tree and ring.

Mesh topology: In this type of topology, every node has a dedicated point to point link to every other node in the netwok. This means each link carries traffic only between the two nodes it connects. If n is total no of nodes in network No. of links to connect these nodes in mesh = N (N-1)/2 Each node should have (N-1) I/O ports as it require connection to every another node.

Mesh Topology with Diagram

Advantages: No traffic problem as there are dedicated links.

Robust as failure of one link does not affect the entire system.

Security as data travels along a dedicated line.

Points to point links make fault identification easy.

Disadvantages: The hardware is expansive as there is dedicated link for any two nodes and each device should have (n-1) I/O ports.

There is mesh of wiring which can be difficult to manage.

Installation is complex as each node is connected to every node.

Star Topology: in this type of arrangement, each node has dedicated point to point connection to a central controller hub. As there are no dedicated links between nodes this topology does not allow direct traffic between nodes.

Star topology with diagram

Advantages: Star topology is less expensive than a mesh topology as there are no dedicated links between nodes and each device needs only one link and one I/O ports to connect it to any number of nodes.

Easy to install and make configurations.

Robust as failure of one link does not affect the entire system. The remaining system will be active.

Disadvantage: More cabling is required in a star than in other topologies (except mesh). Entire network collapse if central controller fails.
 

Tree Topology: As its name implies in this topology devices make a Tree structure. This is an advanced version of star topology as central controllers of star topology work as secondary hub. All these Secondary Hubs gets connected to Central hub or Primary Hub that controls the traffic to the network. Most Devices are connected to secondary hubs. The central contains a repeater, which is a hardware device that regenerates the received bit patterns.

Tree Topology with Diagram

Advantages: Central hub (repeater) increases the distance a signal can travel between devices.

Disadvantages: More cabling is required in a tree than in other topologies (except mesh).

Entire network collapse if central Hub fails.

Bus Topology: In such type of topology, long backbone cable is used to link all the devices in the network. Drop lines and taps are used to connect node to this backbone. A drop line is a connection between the node and the Backbone. A tap is the connector.

Bus Topology with Diagram

Advantages: Requires less cabling compared to mesh, star and tree topologies.

Easy to install.

Disadvantages: It's Difficult to add new devices.

Difficult reconfiguration and fault isolation.

A fault in Backbone stops all transmission, even between devices on the same side of the problem because of noise generated by faulty point.

Ring Topology: All nodes are connected in ring structure. Each node contains repeater. A signal passes node to node, until it reaches its destination. If a node receives a signal intended for another node its repeater regenerates the signal and passes it.

Ring Topology with Diagram

Advantages: Relatively easy to install and reconfigure.

Easy to add new node as only two connections need changes.

Disadvantages: A fault in the ring can disable the entire network. This weakness can be solved by using a dual ring.