Network Topology

Network Topology refers to the layout of the computers and devices in a communications network.

There are two types of topology:
1) Pyhsical Topology
         It is the arrangement of a cabling. Pyhsical design of a network including the devices, location            and cable installation.

2) Logical Topology
         It is the path data travels between computers on a network. This shows how data is actually                  transferred in a network as opposed to its pyhsical design.

Types of Network Topology
1) Star Topology

All the computers and other devices and other nodes on the network connect to a central device, thus forming a star.

Advantages:
    - if one node fails, only that nodes is affected. The other nodes continue to operate normally
    - easy to install and maintain. Nodes can be added or removed from network with little or no                      disruption.
    - easy to troubleshoot and isolate problem when the hosts fails. Simply repair or replace the host               and the network will continue to function.

Disadvantages :
    - if the hub or switch fails, the entire network will be inporable until the devices repaired.
    - network speed decreases when the number of nodes increases
    - more expensive
    - requires more cable than most of the other topologies

2) Bus Topology

It consists of a single central cable (backbone), to which all computers and other nodes connect to.

Advantages :
    - Inexpensive and easy to install. New devices can be added to the backbone.
    - Computers and other nodes can be attached and detached at any point on the bus without disturbing the rest of the network.
    - Failure of one node usually does not affect the rest of the bus network.

Disadvantages:
    - If the backbone fails, the entire bus network will be affected because all system on the network connect to a single cable or backbone, a break in the cable will prevent all systems from accessing the network.
    - It is difficult to identify the entire network shut down. Nodes fail- fail network, ip configuration error, cable network break, etc

3) Ring Topology

A cable forms a closed loop(ring) with all computers and devices arranged along the ring.

Advantages:
    - The transmission of data is relatively simple as packets travel in one direction only.
    - Cable faults are easily located, making troubleshooting easier.
    - The uses of token(information) passing enables all nodes in a ring topology to share the networks resources fairly.

Disadvantages:
    - A failure in any cable or device breaks the loop and can take down the entire network.
    - Data packets(token) must pass through every computer. Therefore, this makes it slower.
    - Adding or removing nodes bring down the network temporary.