Topologies
The design used for networking is called a Topology. There are two basic categories of network topologies;
- Physical topologies
- Logical topologies
The shape of the cabling layout used to link devices is called the physical topology of the network. This refers to the layout of cabling, the locations of nodes, and the interconnections between the nodes and the cabling.
A logical topology is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
The basic network topologies are;
Bus Topology –
The advantage of bus topology is its simplicity, easy to configure. Once the computers are physically connected to the wire, all you have to do is install the network software on each computer. All the computers will then be able to see each other without any difficulty. Few drawbacks are that it is very expensive to implement, has a very low speed and if one of the links between any of the computers breaks down the entire network goes down also disconnecting one computer from the network will shut down the entire network.
Ring Topology –
Network cabling scheme in which one cable sequentially connects all nodes and forms a closed loop. A data packet starting from the originating node is examined by the next active node if it is addressed to that node. If it does, it is copied, otherwise it is regenerated and passed on to the next node until it reaches back the originating node and is discarded. This data packet is passed to the nodes in the network with the help of a Token that moves in a clockwise direction in the ring network.
A Ring topology also uses a device called Multi-station Access Unit (MAU) to connect different workstations to form the network. (The fig will give you a better idea on how it works.) One main drawback is that if one workstation goes down the entire network goes down.
Star Topology –
A star topology uses a junction box called Hub to connect computers to one another. All the computers are connected to the Hub that manages the intercomputer communications. In a star topology you can connect computers on-the-fly without causing network failures. Star topologies do not cost a bit more, but they require a Hub, which is an additional hardware, but the increase in reliability in this design is worth the cost.
Mesh Topology –
A network setup where each of the computers and network devices are interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down. This topology is not commonly used for most computer networks as it is difficult and expensive to have redundant connection to every computer. However, this topology is commonly used for wireless networks.
Hybrid Topology –
A network topology that uses two or more network topologies.
