Different Types of network topology | Advantage and disadvantage

What is network topology?

Networking topology refers to the layout and interconnection strategy used for transmission media or the topology for a network is the set of rules for physically concoction and communicating on a given network medium.

When you decide on particular topology for connecting network servers, workstations and other devices, you will need t fellow a number of specifications that tell you how these machines need to be wired together, what type of connectors to each other on the wire. Topology is broken down into two categories , physical and logical.

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Physical topology

Physical topology refers to how the transmission media are wired together . There are major six physical topological but mainly used in LAN the three types of physical topology are but, star and ring.

Bus topology

Bus topology is a network type in which every computer and network device is connected to single cable . When it has exactly two endpoints then it is called linear bus topology.It is the simplest type of topology , but it has drawback .If the cable breaks some where, it splits the network.

Feature of bus topology :

1. It is transmit data only in one direction

2. Every device is connected to a signal cable

Advantage of bus topology :

1. It is cost effective

2. Cable required is least compared to other network topology.

3. Used in small network.

4. Easy to expand joining two cables together

Disadvantage of bus topology:

1. Cables fails then whole networks fails.

2. If network traffic is heavy or nodes are more the performance of the network decrease.

3. It is slower than the ring topology.

4. Cable has limited length.

Ring topology

The ring topology is the common configuration for fiber cable.It is called ring topology because it forms a ring as each computer is connected to another computer with the past one connected to the first . Exactly tow neighbor for each device .

System is connected in a similar fashion to the bus topology, except that two ends of the bus are tied together.

Feature of ring topology :

1. A number of repeaters are used for ring topology with large number of nodes. Because if someone wants to sent some data to the last node in the ring topology with 100 nodes, the the data will pass through , a nodes to reach the 100^th node. Hence to prevent data loss repeaters are used in the network.

2. The transmission is unidirectional, but it can be made bidirectional by having 2 connections between each network node . It is called dual ring topology.

3. In dual ring topology , two ring networks are formed , and data flow is in opposite direction in them,Also if one ring fails, the second ring can act as a backup, to keep the network up.

4. Data is transferred in a sequential manner that is bit by bit .Data transmitted , has to through each node of the network ,till the destination node .

Advantage of ring topology

1) Transmitting network is not affected by high or by adding more nodes, as only the nodes having tokens can transmit data.

2) Each device is linked to only its immediate neighbors ( either physical or logically ) . To add or delete a device required changing only two connections .

3) A ring is relatively easy to install and reconfigure.

4) Adding or deleting the computers disturbs the network activity.

5) Troubleshooting is difficult in ring topology.

6) Failure of one computers disturbs the whole network.

7) In a simple ring , a break in the ring can disable the entire network

Star topology

In star topology , each device has a dedicated point-to-point link only to a central controller, usually called hub. The devices are not directly linked to one another.

Feature of star topology :

1. Every node has its own dedicated connection to the hub.

2. Hub acts as a repeater for data flow

3. Can be used with twisted pair,optical fiber or coaxial cable.

Advantage Of the star topology :

1) In a star, each device needs only one link and one I/O port to connect it to any number of others . This factor also makes it easy to install and reconfigure.

2) Hub can be upgrade easily

3) Easy to troubleshoot.

4) Easy to setup and modify

5) Only that nodes is affected which has failed,rest of the nodes can work smoothly

Disadvantage of star topology :

1. cost of installation is high

2. Expensive to use

3. If the hub fails then the whole network stopped because all the nodes depends on the hub.

4. Performance is based on the hub that is it depends on its capacity

Mesh topology : It is a point- to point connection to other nodes or devices . All the network nodes are connected each other. Mesh has n(n-1)/2 physical channels to link n devices . It is a topology commonly used for wireless networks.

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Advantage of mesh topology :

1. manage high amount of traffic because multiple devices can transmit data simultaneously.

2. A failure of one device dose not cause a break in the network or transmission of data.

3. Adding additional devices dose not disrupt data transmission between other devices.

4. Provides security and privacy.

5. Fault is diagnosed easily.

6. It is robust.

Disadvantage of mesh topology :

1) The cost to implement is higher than other network topology , making it a less desirable option.

2) Building and maintaining the topology is difficult and time consuming.

3) A mesh are related to amount of cabling because every device must be connected to every device must be connected to every other device installing and re connection are difficult

4) Cabling cost is more.