What is topology ? Explain the types of topology ?

Topology :-

It is the arrangement with which computer system or network devices are connected with each other .

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It is the mapping of LAN design .

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A network topology is the pattern in which nodes (i.e., computers, printers, routers or other devices) are connected to a local area network (LAN) or other network via links (e.g., twisted pair copper wire cable or optical fiber cable) .

Types Of Topology :-

1.BUS Topology

2.RING Topology

3.STAR Topology

4.MESH Topology

5.TREE Topology

6.HYBRID Topology

1.BUS Topology :- 

A BUS Topology is a network setup where each computer and network device is connected to a single cable or backbone. Depending on the type of computer network card, a coaxial cable or an RJ-45 network cable is used to connect them together.

Advantages Of BUS Topology :-

1. It works well when you have small network
2. It requires less cable then that of STAR Topology .

Disadvantage Of BUS Topology :-

1. It can be difficult to find out the problems if the whole network goes down .
2. This topology is not great for large network .
3. If the main cable is damaged,the network fails or splits into two .

2.RING Topology :-

Ring topology, also known as Ring network . It is a type of network topology where each node is exactly connected to two other nodes, forward and backward, thus forming a single continuous path for signal transmission .

Based on Data flow there are two types of ring topology :-

1.Unidirectional

2.Bidirectional 

NOTE:-

A Unidirectional ring topology handles data traffic in either clockwise or anticlockwise direction. This data network, thus, can also be called as a half-duplex network. A Unidirectional ring topology is thus easy to maintain compared to the bidirectional ring topology.

Advantages of RING Topology :-

1. Each computer has equal access to resources .
2. There is no need for network server to control the connectivity between workstations.
3. Additional components do not affect the performance of network.

Disadvantage of RING Topology :-

1. MAU’s and network cards are expensive as compared to Ethernet cards and hubs.
2. If one workstation or port goes down, the entire network gets affected.

3.STAR Topology :-

In this topology, every node connects to a central network device, like a hub, switch, or computer. The central network device acts as a server and the peripheral devices act as clients .

Advantages of STAR Topology :-

1. If one computer in this arrangement, fails for some reason then rest of the computer remains functional .
2. It is easy to add other computer to this type of arrangement .

Disadvantages of STAR Topology :-

1. If the central computer , switch or hub fails , then all the network will drop down and all the computer connected with that main computer , switch or hub will be disconnected from the network .
2. The cost to implement this type of arrangement i.r. STAR Topology is very expensive to implement, specially if you are using switch or router as the central network device .

4.MESH Topology:-

It is a type of arrangement in which all the network nodes are individually connected to most of the other nodes . In the mesh topology there is no concept of central computer which pass message to other computer , switch or router .

Advantages of MESH Topology:-

1. Fault can be diagonsed easily .
2. It provides security and privacy .
3. All the connection in this type of arrangement can hold to load individually .

Disadvantages of MESH Topology :-

1. Bulk wiring is required in this type of arrangement . 
2. installation as well as configuration becomes difficult if the connectivity gets more .

5.TREE Topology :-

This topology is a combination of BUS and STAR topology . TREE topologies are frequently used to organize the computer systems in a corporate offices . In tree topology, nodes of the underlying bus network topology are replaced with a complete star topology.

Advantages of TREE Topology :-

1. It is easy to maintain and to find faults .
2. Other network will not get problem if even one of the system gets damaged .

Disadvantages of TREE Topology :-

1. A lot of maintainence is needed .
2. A lot of cable is needed for this type of arrangement .

6.HYBRID Topology :-

It is a type of topology which uses two or more than two types of topologies or arrangement in a network is called as HYBRID Topology , they can include any type of topologies for the combination like BUS , STAR , RING , MESH , TREE .

e.g.(i) BUS and STAR HYBRID Topology :-

It is a combination of STAR and BUS Topology , many star topologies are attached with a bus topology .

(ii)RING and STAR HYBRID Topology :-

It is a combination of ring and star topology , many STAR topologies are attached with a RING topology .