Types of Network Topology
There are two major categories of Network
Topology i.e. Physical Network topology and Logical Network Topology. Physical
Network Topology refers to the actual structure of the physical medium for the
transmission of data. Logical network Topology refers to the transmission of
data between devices present in the network irrespective of the way devices are
connected. The structure of the network is important for the proper functioning
of the network. one must choose the most suitable topology as per their requirement.
Types of Network Topology
Below mentioned are the types of Network
Topology
Table of Content
- Point-to-Point Topology
- Mesh Topology
- Star Topology
- Bus Topology
- Ring Topology
- Tree Topology
Point-to-Point Topology
Point-to-point topology is a type of topology that works on the functionality of the sender and receiver. It is the simplest communication between two nodes, in which one is the sender and the other one is the receiver. Point-to-Point provides high bandwidth.
Mesh Topology
In a mesh topology, every device is connected to another device via a particular channel. Every device is connected to another via dedicated channels. These channels are known as links. In Mesh Topology, the protocols used are AHCP (Ad Hoc Configuration Protocols), DHCP (Dynamic Host Configuration Protocol), etc.
- Suppose, the N number of devices are connected with
each other in a mesh topology, the total number of ports that are required
by each device is N-1. In Figure, there are 6 devices connected to each
other, hence the total number of ports required by each device is 5. The
total number of ports required = N * (N-1).
- Suppose, N number of devices are connected with each
other in a mesh topology, then the total number of dedicated links
required to connect them is N C 2 i.e. N(N-1)/2. In
Figure, there are 6 devices connected to each other, hence the total
number of links required is 6*5/2 = 15.
Advantages of Mesh Topology
- Communication is very fast between the nodes.
- Mesh Topology is robust.
- The fault is diagnosed easily. Data is reliable
because data is transferred among the devices through dedicated channels
or links.
- Provides security and privacy.
Disadvantages of Mesh Topology
- Installation and configuration are difficult.
- The cost of cables is high as bulk wiring is required,
hence suitable for less number of devices.
- The cost of maintenance is high.
A common example of mesh topology is the
internet backbone, where various internet service providers are connected to
each other via dedicated channels. This topology is also used in military
communication systems and aircraft navigation systems.
Star Topology
In Star Topology, all the devices are
connected to a single hub through a cable. This hub is the central node and all
other nodes are connected to the central node. The hub can be passive in nature
i.e., not an intelligent hub such as broadcasting devices, at the same time the
hub can be intelligent known as an active hub. Active hubs have repeaters in
them. Coaxial cables or RJ-45 cables are used to connect the computers. In Star
Topology, many popular Ethernet LAN protocols are used as CD (Collision
Detection), CSMA (Carrier Sense Multiple Access), etc.
Advantages of Star Topology
- If N devices are connected to each other in a star
topology, then the number of cables required to connect them is N. So, it
is easy to set up.
- Each device requires only 1 port i.e. to connect to
the hub, therefore the total number of ports required is N.
- It is Robust. If one link fails only that link will
affect and not other than that.
- Easy to fault identification and fault isolation.
- Star topology is cost-effective as it uses inexpensive
coaxial cable.
Disadvantages of Star Topology
- If the concentrator (hub) on which the whole topology
relies fails, the whole system will crash down.
- The cost of installation is high.
- Performance is based on the single concentrator i.e.
hub.
A common example of star topology is
a local area network (LAN) in an office where all computers
are connected to a central hub. This topology is also used in wireless networks
where all devices are connected to a wireless access point.
Bus Topology
Bus Topology is a network type in which
every computer and network device is connected to a single cable. It is
bi-directional. It is a multi-point connection and a non-robust topology
because if the backbone fails the topology crashes. In Bus Topology,
various MAC (Media Access Control) protocols are followed by LAN ethernet
connections like TDMA, Pure Aloha, CDMA, Slotted Aloha,
etc.
Advantages of Bus Topology
- If N devices are connected to each other in a bus
topology, then the number of cables required to connect them is 1, known
as backbone cable, and N drop lines are required.
- Coaxial or twisted pair cables are mainly used in
bus-based networks that support up to 10 Mbps.
- The cost of the cable is less compared to other
topologies, but it is used to build small networks.
- Bus topology is familiar technology as installation
and troubleshooting techniques are well known.
- CSMA is the most common method for this type of
topology.
Disadvantages of Bus Topology
- A bus topology is quite simpler, but still, it
requires a lot of cabling.
- If the common cable fails, then the whole system will
crash down.
- If the network traffic is heavy, it increases
collisions in the network. To avoid this, various protocols are used in
the MAC layer known as Pure Aloha, Slotted Aloha, CSMA/CD, etc.
- Adding new devices to the network would slow down
networks.
- Security is very low.
A common example of bus topology is the
Ethernet LAN, where all devices are connected to a single coaxial cable or
twisted pair cable. This topology is also used in cable television networks.
Ring Topology
In a Ring Topology, it forms a ring
connecting devices with exactly two neighboring devices. A number of repeaters
are used for Ring topology with a large number of nodes, because if someone
wants to send some data to the last node in the ring topology with 100 nodes,
then the data will have to pass through 99 nodes to reach the 100th node. Hence
to prevent data loss repeaters are used in the network.
The data flows in one direction, i.e. it
is unidirectional, but it can be made bidirectional by having 2 connections
between each Network Node, it is called Dual Ring Topology. In-Ring
Topology, the Token Ring Passing protocol is used by the workstations to
transmit the data.
The most common access method of ring topology is token passing.
- Token passing: It is a network access method
in which a token is passed from one node to another node.
- Token: It is a frame that circulates
around the network.
Operations of Ring Topology
- One station is known as a monitor station
which takes all the responsibility for performing the operations.
- To transmit the data, the station has to hold the
token. After the transmission is done, the token is to be released for
other stations to use.
- When no station is transmitting the data, then the
token will circulate in the ring.
- There are two types of token release techniques: Early
token release releases the token just after transmitting the data
and Delayed token release releases the token after the
acknowledgment is received from the receiver.
Advantages of Ring Topology
- The data transmission is high-speed.
- The possibility of collision is minimum in this type
of topology.
- Cheap to install and expand.
- It is less costly than a star topology.
Disadvantages of Ring Topology
- The failure of a single node in the network can cause
the entire network to fail.
- Troubleshooting is difficult in this topology.
- The addition of stations in between or the removal of
stations can disturb the whole topology.
- Less secure.
Tree Topology
Tree topology is the variation of the Star
topology. This topology has a hierarchical flow of data. In Tree Topology,
protocols like DHCP and SAC (Standard Automatic
Configuration) are used.
In tree topology, the various secondary hubs are connected to the central hub which contains the repeater. This data flow from top to bottom i.e. from the central hub to the secondary and then to the devices or from bottom to top i.e. devices to the secondary hub and then to the central hub. It is a multi-point connection and a non-robust topology because if the backbone fails the topology crashes.
Advantages of Tree Topology
- It allows more devices to be attached to a single
central hub thus it decreases the distance that is traveled by the signal
to come to the devices.
- It allows the network to get isolated and also
prioritize from different computers.
- We can add new devices to the existing
network.
- Error detection and error
correction are very easy in a tree topology.
Disadvantages of Tree Topology
- If the central hub gets fails the entire system fails.
- The cost is high because of the cabling.
- If new devices are added, it becomes difficult to
reconfigure.
A common example of a tree topology is the
hierarchy in a large organization. At the top of the tree is the CEO, who is
connected to the different departments or divisions (child nodes) of the
company. Each department has its own hierarchy, with managers overseeing
different teams (grandchild nodes). The team members (leaf nodes) are at the
bottom of the hierarchy, connected to their respective managers and
departments.
Hybrid Topology
Hybrid Topology is the combination of all
the various types of topologies we have studied above. Hybrid Topology is used
when the nodes are free to take any form. It means these can be individuals
such as Ring or Star topology or can be a combination of various types of
topologies seen above. Each individual topology uses the protocol that has been
discussed earlier.
The above figure shows the structure of the Hybrid topology. As seen it contains a combination of all different types of networks.
Advantages of Hybrid Topology
- This topology is very flexible.
- The size of the network can be easily expanded by adding
new devices.
Disadvantages of Hybrid Topology
- It is challenging to design the
architecture of the Hybrid Network.
- Hubs used in this topology are very
expensive.
- The infrastructure cost is very high as a hybrid
network requires a lot of cabling and network devices.
A common example of a hybrid topology is a
university campus network. The network may have a backbone of a star topology,
with each building connected to the backbone through a switch or router. Within
each building, there may be a bus or ring topology connecting the different
rooms and offices. The wireless access points also create a mesh topology for
wireless devices. This hybrid topology allows for efficient communication
between different buildings while providing flexibility and redundancy within each
building.
Why is Network Topology Important?
Network Topology is important because it
defines how devices are connected and how they communicate in the network. Here
are some points that defines why network topology is important.
- Network Performance: Upon choosing the
appropriate topology as per requirement, it helps in running the network
easily and hence increases network performance.
- Network Reliability: Some topologies like
Star, Mesh are reliable as if one connection fails, they provide an
alternative for that connection, hence it works as a backup.
- Network Expansion: Choosing correct topology
helps in easier expansion of Network as it helps in adding more devices to
the network without disrupting the actual network.
- Network Security: Network Topology helps
in understanding how devices are connected and hence provides a better
security to the network.
Conclusion
In conclusion, network topologies play a
crucial role in determining the efficiency and reliability of a computer
network. Each topology, whether it's bus, star, ring, mesh, or tree, offers
unique benefits and potential drawbacks. By understanding these different
arrangements, network designers can choose the most appropriate topology to
meet the specific needs of their systems, ensuring optimal performance and
connectivity.
1. “As we already discussed in
our guide on [What is a Software?], every computer system requires both
hardware and software to function within a network.”
2. “Students who are curious
about careers in IT should also explore our article on [What is Software Engineering?], where we explain how network design fits into the bigger picture
of system development.”
3. “If you are new to
computers, you may also want to check our detailed post on [Computer Parts Name with Functions], which will help you understand the devices used in different
topologies.”
4. “The role of an [Operating System] is also crucial in managing data traffic inside any network topology.”
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