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Computer Networks• A computer network is basically a collection of

computers which are connected to each other. It is an interconnection of computers for the purposes of sharing information and resources.

• A popular example of a computer network is the internet, which allows millions of users to share information.

An example of a network

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Router

Internet

Cable Node

Hub

Hub

Bridge

TOPOLOGYThere are certain rules or methods so as to

connect the computers to each other.Hence, here the word TOPOLOGY exists.A Topology is a map of computer which

allows how to connect computers with each other.

It is a physical connection of computers within a particular network.

It defines the nodes and cables that together makes up a network.

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Types of TopologyGenerally, there are 3 types of topologies.

They are :- Bus Topology Star Topology Ring TopologyNow besides these 3 topologies, there is one

more topology named as Mesh Topology which is the combination of star and ring topology. It comes under Hybrid Networks.

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Network Topologies1. Bus Topology

– In this network, all computers are connected through single cable and all the nodes or computers do transmission and reception of messages or data using single cable.

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Bus TopologyAdvantages Disadvantages

Such networks is easy to build and install.

It is inexpensive and easy to use it.

If one node fails, others are not affected.

The failure of the cable brings the whole network to shut down.

At a time, only 1 node can transmit signals due to which the communication becomes slow.

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2. Ring Topology

– The ring network is like a bus network, but the “end” of the network is connected to the first node.– Nodes in the network use tokens to communicate with each other.

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Ring TopologyAdvantages Disadvantages

Ring networks are moderately easy to install.

Cable faults are easily located making troubleshooting easier.

Failure of one computer affects the whole network.

Adding or removing computers is difficult to achieve.

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3. Star Topology

Each node is connected to a device in the center of the network called a hub.

The hub simply passes the signal arriving from any node to the other nodes in the network.

The hub does not route the data.

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Hub

Star Topology

Advantages DisadvantagesThe failure of a single

computer or cable does not bring down the entire network.

Failure of the central hub causes the whole network to shut down.

It is slightly expensive than Bus Topology.

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4. Mesh Topology– Mesh topology is the combination of star and ring topologies.

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Mesh Topology

Advantages Disadvantages

It is more reliable than compared to other topologies.

Data can be transmitted easily even if there is a heavy traffic within the network.

It is very expensive.It includes lots of nodes

and cables for connections.

Due to this, adding or removing of nodes is difficult to attain.

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Recommendations

For single or a small group of users, it is suggested to use a bus or ring topology as it is cheap and easy to install and use.For a company or a big organization, it is better to fix mesh or star topology. Although it is an expensive network but, it will yield good and satisfying performance.

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ConclusionHence, we can say that a topology is

geometric representation of the relationship

of all the linking devices to one another.

Despite having some merits and demerits,

these various topologies can be utilized

according to the user’s needs and desires.

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Acknowledgement

Website - www.wikipedia.com

Data Communications And Networking - by

Behrouz A. Forouzan

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