What is a network topology?
– The various elements of a computer network such as nodes, links and so on can be arranged in a number of ways which are defined by a network topology.
– The topology of a network defines its structure and there are two ways in which it can be depicted namely the physical topology and the logical topology.
– Physical topology is actually how the network components are actually placed and is inclusive of the cable installation and device location.
– For example, when in physical links between the devices are mapped; the resulting geometric shape is the physical topology of the network.
Types of Physical Topologies
Eight basic physical network topologies have been defined so far:
1. Point – to – point topology:
– Simplest permanent links between any two points can be established using this topology.
– It is even the easiest to understand.
– To the user the point – to – point communications channel appears as if it is permanently associated with two points.
– Permanent circuits using this topology can be established using the many available switched telecommunications systems.
– They form the basic telephony model when used with the packet switching and the circuit switching technologies.
– The communication between the two points is unimpeded.
2. Bus topology:
– This topology connects every node i.e., the server or the computer to a single bus cable.
– A signal transmitted by the source travels to all the connected systems until the recipient is found.
– If a system is not the intended recipient, the data is just ignored.
– If it is the intended recipient, it accepts the data.
– Since the topology uses only one cable, it costs very less to implement in comparison with the implementation of the other topologies.
– However, the topology requires a lot of management.
– Furthermore since the network operates up on one cable, it is also the single point of failure.
3. Star topology:
– In the networks in which star topology is followed a connection is given between the central hub and every network host using point – to – point communication channels.
– Here, every node connects to a hub or switch which represents the central node.
– This switch serves as the server while the peripherals serve as the clients.
– It is not necessary that a star shape must be formed by the network but all nodes should bear a connection to the central hub.
– One major function of this hub is to act as a signal repeater.
– Also, this topology is the easiest among all to be designed and implemented.
– It provides the advantage of adding nodes to it with much ease.
– Hub being the single point of failure is the basic disadvantage.
4. Circular or ring topology:
– This network topology resembles a circular geometry in which the data flow is unidirectional.
– Plus unlike the star topology where the only repeater is the central hub, here each node acts as a repeater so that the signal can be kept strong throughout the transmission process.
– This network topology however depends up on the signal’s ability to travel from device to device in the ring.
– When data is transmitted from the source it has to travel through each device until it reaches the one for which it is intended.
5. Mesh topology:
– Networks can exhibit this topology in two ways: fully connected mesh and the partially connected mesh.
– A shortest path between the nodes is taken for transmitting the data using technologies such as shortest path bridging.
6. Tree topology:
– In this topology, there is one root node at the top most level of hierarchy.
– Other nodes lie at the lower hierarchy levels and connected to the root via point – to – point links.
– The scalability characteristic of this topology if of great advantage.
– More nodes can be connected to the root via secondary nodes.
7. Hybrid topology: Mix of other topologies.
8. Daisy chain topology: It is formed from two basic forms namely the linear topology and the ring topology.