Lesson 6 - Network Topology

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. 1. This topology is very low cost effective. Because only lines are required to connect nodes.
2. 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. 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. 1. There is no central host node for making routing decision.
2. 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. 1. Communication will delay if number of nodes are more or increased in a network.
2. 2. It requires more complicated control than star topology.