Network Topology and Types

Network Topology

Network topology refers to the arrangement of the computer connected in the network through some physical medium such as cable, optical fibers etc.

The major goal of topology is to find out the most economical and efficient way to all the users to the network resource

Type of Network Topologies

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

Bus Topology

A bus topology is also known as linear topology. It consist of several computers that are attached to a common cable called a bus , which is the backbone for the network.

In Bus topology ,all the computers and servers are attached to the same communication channel.

At the cable’s start and end points a special device called a terminator is attached to indicate that the network is not available beyond the point.

Coaxial cable is used for media and T-connector is used to terminate the data.

Advantages:

1. It is simple reliable and easy to install and use.
2. It is easy to extend (any numbers of computer can be connected by using a connector in the bus)
3. It is less expensive than other arrangement because it uses coaxial cable.

Disadvantages:

1. If the cable fails, then the entire system fails to respond to the user.
2. Fault finding and troubleshooting becomes very difficult due to single cable.
3. Data traffic is high.

Star Topology

In star topology, all the computers are connected to a centrally located device called “hub”. The center node (hub) is connected to a powerful computer known as server.

The computers are not directly linked to each other and communicate only through a host computer.

The routing function is performed by host computer ,which centrally controls communication between any two other computers by establishing a logical path between them.

Advantages:

1. If one node or its connection breaks it doesn’t affect the other computers and their connections.
2. Devices can be added or removed without disturbing the network.

Disadvantages:

1. It is more expensive than bus topology as it requires extra cables and other controlling devices.
2. Failure of the hub or server makes the entire system disturbed.
3. Data transmission rate is low

Ring Topology

In ring topology , all the computers/nodes are connected to each other in such a way that they make a closed loop.

Ring topology passes data in only one direction. If the failure of one node can affect the entire network.

Advantages:

1. Easy to install
2. Short cable length then star topology
3. There is no dependency on central node.

Disadvantages:

1. Failure of any one computer on the network affect the entire system.
2. Adding and removing the computers are difficult.
3. Difficult to diagnose faults.

Tree/Hierarchical topology

The tree topology arranges computers in a hierarchical structure in order to allow greater control and easier troubleshooting, so that it is also known as hierarchical topology.

The computer in upper level act as a server and at lower level act as client.

This type of network mostly used in organization  where headquarters communicate with regional office and regional office communicate with district office.

Advantage:

1. Easy to extend

Disadvantage:

1. If main device fails to operate , the entire network is disturbed

Mesh Topology

In mesh topology, each computer is connected to every other computer in point-to-point mode. For example, if we have a four computers ,we must have six links.

Advantage:

1. If any one of the computer is down then the computers can still continue to work .
2. Fast communication
3. Directly communicate with each other.

Disadvantages:

1. It is very complex to implement and hard to find out the fault.
2. It is expensive ,as it requires a lot of I/O ports and more cables

Hybrid Topology

Hybrid topology is a Combination of two or more Topology.

In above figure, three different topology is used to make new topology.

Advantage :

1. Can be managed a large volume of nodes.
2. flexibility to modify the network 
3. if one node fails it will not affect the whole network

Disadvantage:

1. Complex design. Expensive to implement

Read Also : Type of Computer Network