Topology of Network

Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network's various components, including device location and cable installation, while logical topologyshows how data flows within a network, regardless of its physical design. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.
A good example is a local area network (LAN): Any given node in the LAN has one or more physical links to other devices in the network; graphically mapping these links results in a geometric shape that can be used to describe the physical topology of the network. Conversely, mapping the data flow between the components determines the logical topology of the network.

Diagram	Kind of Topology	Description, Advantages, and Disadvantages
	Ring	Description: Devices are connected from one to another to form a ring shape. Each host is connected to the next and the last node is connected to the first. A data token1 is used to grant permission for each computer to communicate. Advantages: Easy to install and wire. Because every computer is given equal access to the token, no one computer can monopolize the network. Disadvantages: Requires more cable than a bus topology. If one computer fails it can affect the whole network. It is difficult to identify the problem if the entire network shuts down.
	Bus	Description: All hosts are connected to the backbone cable in a linear2 fashion. Advantages: Easy to connect a computer or peripheral. Requires less cable length than a star topology. Disadvantages: If there is a break in the backbone cable, the entire network shuts down. Both ends of the backbone cable require terminators. It is difficult to identify the problem if the entire network shuts down.
	Star	Description: All hosts are connected to a single point of concentration. Usually uses a hub3 or switch4 as a center node. Range limits are about 100 meters from the hub Data on a star network passes through the hub or concentrator before continuing to its destination. Advantages: It is easy to modify and add new computers to a star network without disturbing the rest of the network. If one node or workstation (beside the middle node) goes down, the rest of the network will still be functional. The center of a star network is a good place to figure out where the network faults are located. You can use several cable types in the same network if the hub you have can handle multiple cable types. Disadvantages: Requires more cable than a bus topology. If the middle node goes down , then the entire network goes down. It is more expensive than because all cables must be connected to one central point.
	Mesh	Description: Each host is connected to all the other hosts. Advantages: Increased reliability since there are multiple paths for each node to take. Increased speed since shortcuts have been created by add more cables/links. Disadvantages: The cost of cabling all the hosts together is expensive and time consuming.

more deep explanation of some like up diagram :) 

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)



RESOURCES : http://www.sis.pitt.edu/~icucart/networking_basics/networking_topology.html , http://en.wikipedia.org/wiki/Network_topology , https://www.google.com/search?output=search&sclient=psy-ab&q=type+of+topology&btnK= , http://compnetworking.about.com/od/networkdesign/a/topologies.htm , http://whatis.techtarget.com/definition/network-topology