NETWORK TOPOLOGY Network topology is the study of the arrangement or mapping of the elements of a network,especially the physical and logical interconnection between nodes. Classification : 1.physical topology 2.signal topology 3.logical topology
TOPOLOGY The topology of a network is geometric representation of all the links and linking devices to each other. There are five basic topology Bus Topology Ring Topology Star Topology Mesh Topology Hybrid Topology
BUS TOPOLOGY In this topology a number of computers are attached with a single cable And two terminators are connected at the two end of the cable. This cable or connector is called Bus. So this topology is called Bus Topology. Hence the network operate system keeps the unique electronic address of each computer. So that the data from one computer to another computer transfer correctly.
ADVANTAGES *It is simple, reliable and easy to use for small size local area network. *It requires least amount of cable. *It is easy to extend a bus. DISADVANTAGES *The data transfer becomes slower due to increase in size of bus. Before checking whether the bus is free or not. If the bus is transmitted data of another node, then the node wait until the end of transmission. *It is difficult to find out any error within the bus. Any breakage or loose connection may affect the total network.
EXAMPLES OF BUS TOPOLOGY # ETHERNET # CSMA/CD(Carrier Sense Multiple Access/Collision Detection)
RING TOPOLOGY It is similar to the linear bus topology. In Bus topology we use linear bus whereas in ring topology we use circular bus. In this topology each node is physically connected to other two nodes. The data transfer from the source node to the destination node through the other nodes in between them. Since each computer receives data, so they are always active network. So the signal loss problem is not created which is possible in bus topology. In this topology there is no terminal node. This type of topology can be found in peer-to- peer network.
ADVANTAGES It is faster because data is transformed to all the computers. In this topology the computer can not monopolized the network because each computer have equal access to the token. In this network it allows to share the network gracefully.
DISADVANTAGES Failure of one computer on the ring affects the whole network. It is difficult to find out the problem within the network. Adding or removing computers disturbs or affects the network.
EXAMPLES OF RING TOPOLOGY IBM Token Ring FDDI (Fiber Distributed Data Interface)
STAR TOPOLOGY In a star network communication a computer acts as a control hub and other computers are connected to that hub. The central hub works as server and it receives the message from different computer and sends to the destination computer.
The hub can be active or passive. An active hub regenerates electrical signal and sends it to all the computers connected to it. This type of hub is often called as multiport repeater. It requires electrical power to run. The passive hub acts as a connector point and does not regenerate or amplify signals. It do not require electrical power. We can use several types of cables to implement a star network.
ADVANTAGES It is much easier to modify or to add new computer to a star network. Single computer failure do not affect the whole star network. We can use several cable types in the same network.
DISADVANTAGES If the central hub fails then the whole network fails to operate. Many star network requires a device at the central point to rebroadcast. It costs more to cable a star network.
MESH TOPOLOGY In mesh topology, every device has a dedicated point-to-point link to every other device, i.e.each computer is connected to other computers directly.
ADVANTAGES As the links are dedicated, so each connection can carry its own data load. In this topology if one device became unuseable or defective, then it does not affect the whole network. Another advantage is privacy or security as each have dedicated line.
DISADVANTAGES It requires high amount of cabling. The hardware required to connect each link can be expensive.
HYBRID TOPOLOGY The hybrid topology is a network topology that is composed of interconnection of two or more network that are based up on different physical topologies.
Two or more topologies are combined to form a hybrid topology. There are two types of hybrid topology. * Star Bus Topology * Star Ring Topology