Network topologies
Definition
A network topology is the study of the arrangement or the mapping of the
elements of a network, especially the physical and logical interconnections
between nodes. It is also the name given to the physical layout or shape of a
network. Types of network topologies
1. Bus network topology.
In bus topologies, it is a single cable that joints all the workstations, printer, files
server, and other components together. This network transmits data, instructions, and
information in both directions. At each end of the bus is a “terminator.” This is a piece of
hardware which prevents signals bouncing back and forth (echoes). When the sender
transmits data, the destination address must be included in the transmission.
a. Advantages
• Easy and inexpensive to set up as little cabling is required
• Easy to include additional stations without disrupting the
network Failure of one node does not affect network
b. Disadvantages
• High rate of data collision
• Fails if there is any damage to the bus
• Any break in the bus is difficult to identify
2. Ring network topology.
In a Ring topology, all the computers are connected to one another by a cable which
forms a close loop or a ring (circle form). Data transmitted on a ring network, travels along
the entire ring from one computer to the next in one direction until it reaches the final
destination computer
A. Advantage
• No collision as a station needs the token to transmit
• Each computer acts like a repeater so signals are not attenuated
B. Disadvantage
• If a node in the network fails, the entire network fails
• Network is disrupted when additional stations are added
3. Star network topology.
In a star topology, each workstation or communication device is connected to the
central computer or server by means of its own unique link. The central computer provides
a common connection point for devices in the network. This common connection point in
a star network is called a hub. The data transferred from one computer to another passes
through a hub.
Star networks are commonly used in schools and offices because they tend to be the most
reliable of the topologies
a. Advantages
• Breakdown of a node does not affect the network
• No disruption of the network when connecting or removing
devices
• It is easy to detect faults
b. Disadvantage
• Failure of the central node affects the entire network
• It is costly due to the amount of cables required to connect the
devices
4. Tree network topology.
This is a network pattern that has both the characteristics of a bus and star
topologies. It is made up of branches that indirectly meet at a control point and offers only
one transmission path between any two stations. In a tree topology, nodes are arranged
hierarchically thus also called hierarchical topology.
5. Mesh network topology.
This is a network that contains all the above topologies and is usually common in
very large networks such as the internet. It has a structure with multiple message channels
between nodes. Each node is connected to an arbitrary number of neighbors in such a way
that there is at least one traversal from any node to any other.
