Network Topology

                                           Network Topology

The physical arrangement of computers in a network is called as topology. The path taken by data from sender to receiver computer mainly depends upon the topology of the network. Every computer is linked to the network but the way how it is linked is different in different topologies:

The choice of topology depends upon the following factors:

1.   Cost

2.   Availability of physical communication line.

3.   Reliability of the entire system.

4.   Number of cables required.

5.   Expandability of the system.

6.   Transmission delays.

7.   Maximum distance.

8.   Maximum number of nodes.

In LAN, various topologies exist.

STAR Topology

Star Topology is forerunner of all other topologies. Here, every PC on the network is connected to a central controller, called Hub as shown below:

It is topology upon which our telephone network is built. Every communication from every user’s station goes though the central controller before reaching it destination. This network is cheapest of all. To connect five systems we just need five cables. But failure chances are more if hub fails, whole network will go down. The star topology is very easy to install and reconfigure. The stations can be added or removed without affecting the working of other nodes on the network. Here, only one connection is needed to add a single node to the network.

Merits:

1.   Cheaper media of networking.

2.   Less number of Cables required.

3.   Transmission delays between two nodes do not increase by adding new nodes to the network.

4.   If any node fails, the remaining portion of the network is unaffected.

5.   Easy to add new nodes.

Demerits:

1.   The hub offers limited number of connections.

2.   If hub fails, the entire network fails.

3.   The cabling cost is more since cables must be pulled from all computers to the central hub.

4.   Many star networks require a device at the central point to rebroadcast or switch the network traffic.