NETWORK TOPOLOGY
.1 Topology
The study of network topology recognizes is five basic topologies
*Bus
*Star
*Ring or circular
*Mesh
*Tree
2. Bus topology
Bus Topology are two types:
(a) Linear bus
(b) Distributed bus
Advantages of Bus topologies
2. Star Topology
There are two types of star topology -
(a) Extended star
(b) Distributed Star
Fully connected
* Network topology is the layout pattern of interconnections of the various elements of a computer or biological network. Network topologies may be physical or logical.
* Physical topology refers to the physical design of a network including the devices,
location and cable installation.
* Logical topology refers to how data is actually transferred in a network as opposed to its physical design. In general physical topology relates to a core network whereas logical topology relates to basic network.
The study of network topology recognizes is five basic topologies
*Star
*Ring or circular
*Mesh
*Tree
2. Bus topology
*In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient.
*If the machine address does not match the intended address for the data, the machine ignores the data.
*Alternatively, if the data matches the machine address, the data is accepted. If the network cable is terminated on both ends and when without termination data transfer stop and when cable breaks, the entire network will be down.
Bus Topology are two types:
(a) Linear bus
(b) Distributed bus
(a) Linear bus The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network simultaneously.
(b) Distributed bus The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium.
* A bus uses relatively little cable compared to other topologies and arguably
has the simplest wiring arrangement.
* Since nodes are just attached to the main line, it’s easy to add or remove
nodes from a bus. This makes it easy to extend a bus topology.
Disadvantages of Bus topology
* Diagnosis/troubleshooting (fault-isolation) can be difficult.
* The limited length of the cable in a network restricts the number of devices that can be connected.
2. Star Topology
* In local area networks with a star topology, each network host is connected to a central hub with a point-to-point connection. The network does not necessarily have to resemble a star to be classified as a star network, but all of the nodes on the network must be connected to one central device.
* All traffic that traverses the network passes through the central hub. The hub acts as a signal repeater. The star topology is considered the easiest topology to design and implement.
* An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that the hub represents a single point of failure.
There are two types of star topology -
(a) Extended star
(a) Extended star In this topology the repeaters being used to extend the maximum transmission distance of the point-to-point links between the central node and the peripheral nodes beyond that which is supported by the transmitter power of the central node or beyond that which is supported by the standard upon which the physical layer of the physical star network is based.
(b) Distributed Star A type of network topology that is composed of individual networks that are based upon the physical star topology connected in a linear fashion – i.e., 'daisy-chained' – with no central or top level connection point (e.g., two or more 'stacked' hubs, along with their associated star connected nodes or 'spokes').
Advantages of star topology are as follows
* Troubleshooting and fault isolation is easy.
* Also, it is easy to add or remove nodes and to modify the cable layout.
* Failure in any star network cable will only affect the connected computer and not the entire network.
Disadvantage of this topology are
* If the hub fails, the entire network fails.
* It requires more cable than bus topology.
3. Ring Topology
A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring. The network is dependent on the ability of the signal to travel around the ring.
4. Mesh Topology
In a mesh topology there are at least two nodes with two or more paths between them to provide redundant paths to be used in case the link providing one of the paths fails. Full mesh topology is a network topology in which there is a direct link between all pairs of nodes. In a fully connected network with (n) nodes. Networks designed with this topology are usually very expensive to set up, but provide a high degree of reliability due to the multiple paths for data that are provided by the large number of redundant links between nodes. This topology is mostly seen in military applications
Fully connected
Partially connected The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.
5. Tree Topology
A tree topology is a hybrid physical topology that combines features of star and bus topologies. In this topology multiple star topologies are connected to a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points).
|
The disadvantages of this topology are as follows
* If the root goes down, the entire network goes down.
* If any hub goes down, all branches off of that hub go down.
Access becomes a problem if the entire conglomerate becomes too big.
Categories:
COMPUTING KNOWLEDGE
0 comments:
Post a Comment