Network Topology

Definition

“Network Topology refers to layout of a network and how different nodes in a network are connected to each other and how they communicate.”

Computer network topology is the way various components of a network are arranged. Network topologies define the layout, structure of network means it define the way in which different systems and nodes are connected and communicate with each.

Factors to be taken into consideration while choosing a Network topology

1)  Scale of your project (in terms of number of components (devices) to be connected).
2)  Amount of traffic expected on the network.
3)  Budget allotted for the network i.e. amount of money you are willing to invest.
4)  Required response time

Types of Physical Network Topologies

1) Bus Topology

2)  Star Topology

3)  Ring Topology

4)  Mesh Topology

5)  Tree Topology

6)  Hybrid Topology

1) Mesh Topology

In a mesh network topology, each of the network node, computer and other devices, are interconnected with one another. This type of topology is very expensive as every computer is connected to each other, thus it is not generally used in computer networks.

Advantages of Mesh topology

1) Data can be transmitted from different devices simultaneously. This topology can withstand high traffic.

2) Even if one of the components fails there is always an alternative present. So data transfer doesn’t get affected.

3) Expansion and modification in topology can be done without disrupting other nodes.

Disadvantages of Mesh topology

1) There are high chances of redundancy in many of the network connections.

2) Overall cost of this network is way too high as compared to other network topologies.

3) Set-up and maintenance of this topology is very difficult. Even administration of the network is tough.

2) Star Topology

In Star topology, all the components of network are connected to the central device with a point-to-point connection. Every computer is indirectly connected to every other node by the help of “hub”. 

All the data on the star topology passes through the central device before reaching the intended destination. Hub acts as a junction to connect different nodes present in Star Network, and at the same time it manages and controls whole of the network

Advantages of Star Topology

1.    As compared to Bus topology it gives far much better performance.

2.    Easy to connect new nodes or devices. In star topology new nodes can be added easily without affecting rest of the network. Similarly components can also be removed easily.

3.    Centralized management. It helps in monitoring the network.

4.    Failure of one node or link doesn’t affect the rest of network. At the same time its easy to detect the failure and troubleshoot it.

Disadvantages of Star Topology

1.    Too much dependency on central device has its own drawbacks. If it fails whole network goes down.

2.    The use of hub, a router or a switch as central device increases the overall cost of the network.

3.    Performance and as well number of nodes which can be added in such topology is depended on capacity of central device.

3) Ring Topology

In Ring Topology, all the nodes are connected to each-other in such a way that they make a closed loop. Each workstation is connected to two other components on either side, and it communicates with these two adjacent neighbors. Data travels around the network, in one direction.

Advantages of Ring Topology

1.    This type of network topology is very organized. Also in ring topology all the traffic flows in only one direction at very high speed.

2.    Even when the load on the network increases, its performance is better than that of Bus topology.

3.    Each computer has equal access to resources.

Disadvantages of Ring Topology

1.    Each packet of data must pass through all the computers between source and destination. This makes it slower than Star topology.

2.    If one workstation or port goes down, the entire network gets affected.

3.    Network is highly dependent on the wire which connects different components.

4.    Expensive as compared to star topology.

4) Bus topology

Bus Topology is the simplest of network topologies. In this type of topology, all the nodes (computers as well as servers) are connected to the single cable (called bus), by the help of interface connectors. This central cable is the backbone of the network and is known as Bus. Every computer communicates with the other device through this Bus. 

Advantages (benefits) Bus Topology

1)  It is easy to set-up and extend bus network.
2)  Cable length required for this topology is the least compared to other networks.
3)  Bus topology costs very less.

Disadvantages (Drawbacks) Bus Topology

1)  There is a limit on central cable length and number of nodes that can be connected.

2)  Dependency on central cable in this topology has its disadvantages. If the main cable (i.e. bus ) encounters   some problem, whole network breaks down. 

3)  Proper termination is required to dump signals. Use of terminators is must.

4)  It is difficult to detect and troubleshoot fault at individual station.

5)  Maintenance costs can get higher with time.

6)  Efficiency of Bus network reduces, as the number of devices connected to it increases.

7)  It is not suitable for networks with heavy traffic. 

8)  Security is very low because all the computers receive the sent signal from the source.

5) Hybrid Topology

Hybrid topology is combination of two or more than two topologies. This combination of topologies is done according to the requirements of the organization.