Topology is of two types – Physical Topology and Logical Topology.
Physical Topology is the architecture of a network. It describes how the computers are arranged in a network and how the computers are cabled or connected to each other in the network.
Some of the important Physical Topologies are:
- Bus Topology
- Star Topology
- Ring Topology
- Mesh Topology
In this type of Topology, there is a Central Bus or a Backbone Cable which runs across the Network and all the Computers (or Nodes) are connected to this Central Bus. Any Data which is transmitted through this Bus can be received by any Computer that is connected to it. If anything goes wrong with the Central Bus, which is the Backbone Cable, the Entire Network goes down. This type of Topology follows Serial Communication.
COMPONENTS REQUIRED FOR BUS TOPOLOGY:
- Co-Axial Cable (which is the BackBone Cable)
- BNC Connectors (BNC stands for British Network Connector)
- Patch Cable
In a Star Topology, many Computers are linked to a Central Unit – a Typical Example for this kind of Topology is a Hub to which many Computers (Nodes) are connected. When one of the computers in the Network transmits a signal, it travels to the Hub, which in turn transmits it to all the other computers (Nodes). This kind of network is pretty simple to set up and is quite common in small companies/organizations, in a Workgroup environment.
The Star Topology is more advanced than Bus Topology. It uses a Hub or a Switch and Cat 5 / Cat 6 cables. It also uses RJ45 connectors. (RJ stands for Recommend Jack). It offers faster Data Transfers and Processing.
The Advantages of using Star Topology are:
- Failure of one computer in the network does not affect other computers.
- Multiple cable types can be used – if the Hub supports it.
- Networking costs can be brought down by using the Hub to share devices.
The Ring Topology connects all the Computers (Nodes) in the Network in one Single Path, whose ends are joined to form a Circle (or Ring). This Topology is used with there is a requirement for Fault Tolerance (Redundancy). A device called MSAU (Multi Station Access Unit) is used here, inside which a Logical Ring is formed which ensures the availability of the Network. It was basically implemented in IBM Networks and usually runs around a Campus or a group of buildings to form a high-speed, fault tolerant Network backbone.
CHARACTERISTICS RING TOPOLOGY:
This topology is more fault resistant than the others.
- The Network will not crash even if the capacity is exceeded – instead, it will only function at a much reduced speed.
- The failure of any one computer in the Network can bring down the entire network.
- The entire Network gets affected when adding new computers or removing computers from the Network.
- When compared to the other topologies, this one is difficult to maintain.
In this type of Topology, Every Computer on the Network has a seperate connection to every other computer on the Network. These types of networks are highly Fault Resistant – which means, if any computer in the network stops working, it will not pull down the rest of the network. This is usually too exensive for larger networks and is used widely in smaller networks which are required to be robust and fault resistant. However, this topology can be applied on larger networks also – for example, to connect multiple networks through a mesh of of alternate connections like Fibre Optic cables & Leased lines and even co-axial thicknet cables.