Topologies In Computer Network

The logical layout of the cable and devices that connect the nodes of the network is called Topology.Network designers consider several factors when deciding which topology or combination of topologies to use:the type of computer and cabling(in any) in place,the distance between computers, the speed at which data must travel around the network,and the cost of setting up the network.
                              Data moves through the network in a structure called "Packets".Packets are pieces of a message broken down into small units by sending PC and reassembled by the receiving PC.Different networks format packets in different ways,but most packets have two parts:the header and the payload.the "header" is the first part of the packets,which contains information needed by the network.
The header identifies the node that sent the packet(the source),and provides the address of the node that will recieve the packet(the destination).The network reads each packet's header to determine where to send the packet and, in some cases,to determine the best way to get it to its destination.The header also holds control data that helps the recieving node reassemble a message's packets in the right order.The "payload"is the actual data that is being transmitted between the two nodes.
                                                       A network topologies and related technologies are important for two reasons.first,a correctly designed network,using the most appropriate topology for the organization's needs,will move data packets as efficiently as possible.second,the network topology play a role in preventing collision,which is what happens when multiple nodes try to transmit data at the same time..

      TYPES OF TOPOLOGIES>>>>>>>>>>>>>>>>>>>>>>>>

1. BUS TOPOLOGY: A bus topology network uses one cable,all the nodes and peripheral devices are connected in a series to that cable.A special device, called a terminator, is attached at the cables's start and end points,to stop network signals so they do not bounce back down back down the cable.This topologies main advantage is that it uses the least amount of cabling of any topology.

                               

  2. STAR TOPOLOGY: The star topology is probably the most common topology.In a star    network,all the nodes are connected to device called hub and communicate through it.Data packets travel through the hub and are sent to the attached nodes,eventually reaching their destinations.some hubs known as intelligent hubs can monitor traffic and help prevent collisions.In star topology,a broken connection between a node and the hub does not affect the rest of the network.If the hub is lost,however ,all the nodes connected to thet hub are unable to communicate.

    3.RING TOPOLOGY:The ring topology connects the network's nodes in a circular chain,with each node connected to the next.The last node connected to the first,completing the ring.Each node examines data as it travels through the ring.if the data known as a token is not addressed to the node examining it,the node passes to the next node.There is no danger of collisions because only one packet of data travels the ring at a time .If the ring is broken,however ,the entire network is unable to communicate.

    4.MESH TOPOLOGY:The mesh topology is the least-used network topology and the most expensive to implement.In a mesh environment,a cable runs from every computer to every other computer.If you have four computers,you must six cables-three coming from each computer to the other computers.The big advantage to this arrangement is that data can never fail to be delivered ,if one connection goes down there are other ways to route the data to its destination.

                   "Thanks friends I hope you all learnt about topologies in computer network"