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What is Network Topology ?

Course - Networking Fundamental

Published on 5 Dec 2020 at 04:67

NETWORK TOPOLOGIES

Topologies in network refers to the way in which the nodes in network are connected to one another. It determines the various available path between any pair of nodes in network. Choice of network topology depends upon the various factor:

1. Desired performance of the system.
2. Reliability of the system.
3. Size of the system (Number of host or nodes and their geographical region)
4. Cost of components and services requires to implement network
5. Availability of communication lines.

There are several types of network topologies some of which are defines below:

1. Star topology

In star topology multiple nodes are connected to a host node. Two nodes can communicate in star topology via host nodes because nodes in a network are linked with each other through host node. Basically, host node perform the routing function that controls the communication between two nodes by establishing the logical path between them.

Advantage

Each topology has some advantage and disadvantage. Here we mentioned some advantage of using a star topology.

1. This topology is very low cost effective. Because only lines are required to connect nodes.
2. Transmission delay between two nodes is not increased by adding new node in network, because any two nodes are connected via two link only.
3. If any of the nodes in network fail except host nodes, other nodes are remaining unaffected.

Disadvantage

Apart from advantage star topology also have some disadvantage. The only disadvantage with this topology is that if host nodes is fail under any circumstance entire network is fails.

2. RING TOPOLOGY

Ring topology is another kind of topology in which each nodes has two communicating subordinate (every nodes is connected to its two adjacent nodes), so there is no need of host node or master node for controlling the network.

Every node receive data from any of its two adjacent nodes. The only decision a node has to take is whether the data is for his own use or not. If its addressed to it, utilize it unless it merely passed it to the next node.

Advantage

1. There is no central host node for making routing decision.
2. It more reliable than a star topology because communication is not depend on the single central node. If the link of any two nodes fail, or if any node fail alternate routing is possible.

Disadvantage

1. Communication will delay if number of nodes are more or increased in a network.
2. It requires more complicated control than star topology.

3. COMPLETELY CONNECTED NETWORK

This a more reliable than above two topologies because there is separate physical link for connecting each node to any other node. Each Nodes has a direct link to other nodes in a network, known as point-to-point link. The control is distributed with each node deciding its communicating priorities.

Advantage

1. Most reliable because failure in any link will affect only direct communication between nodes connected by that link.
2. Each node of network need not have individual routing capability.
3. Communication is very fast between any two nodes.

Disadvantage

1. It's a most expensive network from the point of view of link cost.
2. If there is nodes in a network, links are required.

4. BUS TOPOLOGY

Bus topology is option for you to reduce the number of physical link because in this network topology all nodes in a network are connected with the single transmission medium.
When a node want to send a message to another node, it depends destination address to the message and check whether communication line is free or not.

If it busy then as soon as line become free, it broadcast the message on the line and when message is travelling in a line each node check whether the message addressed to it.

Finally message is picked up by the addressed node and then acknowledgement message is sent to sender node and free the line.

Advantage

1. It helps in reducing the number of physical lines.
2. Failure of one node does affect the other nodes working on a network.
3. Addition of a new node is easy.

Disadvantage

1. If the shared transmission line is fails, entire network is fail.

5. Hybrid Topology

Hybrid topology is a collection network of different topology used in a big network.