Introduction to network & topology

Introduction to network 

A network is the connection of  two or more computers or devices,they are linked with each others  to share resources, such as files,pics ,tracks or only play the same game together, exchange files, or allow electronic communications. The computers on a network may be linked through cables(wires), telephone lines(and modems), radio waves(wireless / wi-fi), light beams or even for very long distances via satellites.Network  basically needs both of the components (hardware and software) involved in connecting computers.

 The purpose of a network

To enable the sharing of files and information between multiple systems as sharing files, send message , a whole network of computers to share a single printer, etc. saving time and much less costs.

Types of networks

• PAN : It is usually wireless, established when needed to communicate between two or more devices it is characterized as short-range, often limited to 10 meters or less in range.

•  LAN : Generally,it is  a limited network as the shared data is limited to a geographic area such as laboratory, school, company or building.

• MAN :   A network that spans a citywide area or a town.

• WAN :  To connect networks in larger geographic areas including the while world. using cables or satellite  to connect this type of global network.
  
  
  Topology

            It is a word generally refers to the layout or map of connected devices in a certain network.It shows the shape or structure of the connection between devices. There are two types of network topologies: physical and logical. Physical topology emphasizes the physical layout of the connected devices and nodes, while the logical topology focuses the pattern of data transfer between network nodes.However, both physical and logical topologies can be categorized into the basic models the types of topology.

            Types of Topology  

•   Bus Topology  :A bus topology is a type of network setup where each computer and network device is connected to a single main cable to be as a backbone.

  Advantages:

Easy to connect a computer or any device to a linear bus.
Requires less cable .

Disadvantages:

Entire network shuts down if there is a break in the main cable.
Terminators are required at both ends of the backbone cable.
Difficult to identify the problem if the entire network shuts down.
Not meant to be used as a stand-alone solution in a large building. 

Diagram:

•  Star Topology:The devices and computers on a network connect to a central hub or a switch.In a shape of a star and the center is a hub or a switch.Data on this network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable.
  
  Advantages:
  
  Easy to install .
  No disruptions to the network when connecting  or removing devices. 
  Easy to detect faults and to remove parts.
  With a star topology, expanding a network is  easily done by adding another             device.                                                        
  Disadvantages:
  
  Requires more cable length than a bus topology.
  If the hub, switch, or concentrator fails, all computers connected to that hub would be disconnected.More expensive than linear bus topologies because of the  cost of the switch.
  Diagram:

• Tree Topology : Integrate multiple star topologies together onto a bus topology.Tree topologies allow for the expansion of an existing network, and enable users to configure a network to meet their needs.If the main cable between each of the two star topology networks failed, those networks would be unable to communicate with each other. However, computers on the same star topology would still be able to communicate with each other.

   Advantages:
    Point-to-point wiring for individual segments.

   Disadvantages:

  Overall length of each segment is limited by the type of cabling used.
  If the backbone line breaks, the entire segment goes down.
  More difficult to configure than other topologies.
  Diagram:






                                          

• Ring Topology : In Ring Topology, all the nodes are connected to each-other in such a way that they make a closed loop,every device has exactly two neighbors for communication devices. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise").

Advantages:

In a ring structure, networks do not need a central hub.Installation,troubleshooting and adding 

new devices are also relatively easy with this kind of network.

This type of topology is highly efficient and handles heavier.

Disadvantages:

One failure to transmit data can impact the entire network.

Network is highly dependent on the wire which connects different components.

Diagram:

                             

• Mesh topology: In mesh topology every node or device is connected to every other node and device in the network.

Advantages:
Even if one of the components fails data transfer doesn’t get affected.
Expansion and modification in topology can be done without disrupting other nodes.

Disadvantages:

Overall cost of this network is way too high as compared to other network topologies.
Set-up and adding new devices  of this topology is very  difficult.

Diagram:

• Hybird Topology: In this type of topology we integrate two or more different topologies to form a resultant topology which has good points(as well as weaknesses) of all the included basic topologies rather than having characteristics of one specific . Hybrid topology inherits merits and demerits of all the included topologies. Internet is the best example of largest Hybrid topology.

Advantages:

Fault detection and troubleshooting is easy in this type of topology.

Its easy to increase the size of network by adding new components.

Disadvantages:

 Complex design.

 The hubs used to connect two distinct networks, are very expensive.

 This topology is usually larger in scale,require  a lot of cables, cooling systems, etc.

Diagram: