Computer Network

Computer network is an interconnection of a group of computers. A computer that controls other computer on the network is called a Server. A computer that is controlled by the server is called Client or Workstation

Network topology

Network Topology signifies the way in which intelligent devices in the network see their logical relations to one another

Computer networks may be classified according to the network topology upon which the network is based, such as

                                i.            Bus network,

                              ii.            Star network,

                            iii.            Ring network,

                            iv.            Mesh network,

                              v.            Star-bus network,

                            vi.            Tree or Hierarchical topology network, etc.
Bus
The simplest topology to understand is the Bus. In a Bus, all the devices on the network are connected to a common cable. Normally, this cable is terminated at either end, and can never be allowed to form a closed loop. Figure One shows an example of a Bus network

Bus

The simplest topology to understand is the Bus. In a Bus, all the devices on the network are connected to a common cable. Normally, this cable is terminated at either end, and can never be allowed to form a closed loop. Figure below shows an example of a Bus network.
 
  

Ring

A Ring topology is very similar to the Bus. In a Ring, all the devices on the network are connected to a common cable which loops from machine to machine. After the last machine on the network, the cable then returns to the first device to form a closed loop. Figure below shows an example of a Ring network.

 

Star

A star topology is completely different from either a Bus or a Ring. In a Star each device has its own cable run connecting the device to a common hub or concentrator. Only one device is permitted to use each port on the hub. Figure below shows an example of a Star network.
 

Tree

A tree topology can be thought of as being a "Star of Stars" network. In a Tree network, each device is connected to its own port on a concentrator in the same manner as in a Star. However, concentrators are connected together in a hierarchical manner -- i.e. a hub will connect to a port on another hub. Figure below shows a Tree network.
 

 

Mesh

A Mesh topology consists of a network where every device on the network is physically connected to every other device on the network. This provides a great deal of performance and reliability, however the complexity and difficulty of creating one increases geometrically as the number of nodes on the network increases. For example, a three or four node mesh network is relatively easy to create, whereas it is impractical to set up a mesh network of 100 nodes -- the number of interconnections would be so ungainly and expensive that it would not be worth the effort. Mesh networks are not used much in local area networks (LANs) but are used in Wide Area Networks (WANs) where reliability is important and the number of sites being connected together is fairly small. Figure below shows an example of a four-node Mesh network.