Network topology represents the arrangement of connectivity of devices & nodes in the network. Network topology can be categorized in either physical topology or logical topology. Each network topology has its advantages and disadvantages. When it comes to deciding the topology for any network, Network Administrator can decide on various parameters which network topology is fits to match their requirement.
Definition of Network Topology
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Network topology defines the structure of nodes, devices, and components and how they are interconnected for communication. We can segregate the network topologies in two different ways.
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Physical
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Logical.
Physical – Physical topology refers to the actual connections (wires, cables, etc.) of how the network is arranged.
Logical – The logical topology is a high-level view to understand or design the network setup, how different nodes or sites, or locations are connected in the network.
Different Types of Network Topologies
Point to Point Topology
Point to Point Topology is the easiest topology in which two nodes are connected directly with each other using a common link. The entire bandwidth of this point-to-point link will be dedicated to these two nodes.
The point-to-point network can be established/set up by physically laying the cable between both the nodes or other mediums such as wireless, microwave links, etc. Example:- Two Computers are connected directly with each other using a cross cable.
Advantages of Point to Topology
- Very fast to set up if it’s for the distance between nodes is too much.
- Doesn’t need hardware appliance devices for short length or distance.
- Provides dedicated bandwidth between respective two nodes.
- Troubleshooting becomes very easy since the point of a fault will be limited.
Disadvantages of Point-to-Point Topology
- Since it’s a dedicated link & in case of disconnection, it will impact the entire communication.
- Since it’s a dedicated link for redundancy, we need to have an additional link.
- The cost of a point-to-point link goes very high for a longer distance as it will be dedicated.
BUS Topology
This is one of the simplest types of topology in which nodes are connected with a common bus or common line or main cable in the network. These nodes are connected to a common bus using connectors called taps and dropline cables. This topology is also referred as 
Line topology as it has only a single transmission line for all the nodes/computers.
This bus acts as a backbone of the network which gives connectivity to each node and computer in the network & after the last node at both the end bus use the line terminator.
This type of topology can be used only in the small network due to its limitations & this bus topology is seen very rarely in used in industry nowadays.
Advantages of Bus Topology
- It’s very easy to set up if a network is small.
- If one node goes down, it won’t impact the other nodes.
- The cable requirement for bus topology is very less compared to another topology.
- Performs well in a small network.
Disadvantages of Bus Topology
- It’s very difficult to identify & troubleshoot the problem if the entire network is down.
- It can be implemented for a large network.
- Increasing the nodes reduces the signal strength & decreases the network performance.
- If the bus fails entire network will go down.
Star Topology
Star topology is one of the common topology used in most of the organization, especially in LAN Network. In Star topology, all the nodes /computers are connected to a central device such as Switch, Hub, or Router and communicate with each other through this central device.
Advantages of Star Topology
- If one of the nodes goes down other nodes will not get impacted and will be able to communicate with each other.
- Easy to set up as connectivity of node has to be done only till central device.
- This type of topology is very scalable and nodes can be added immediately in a free port in Switch.
Disadvantages of Star Topology
- If the central device (switch or hub or router) goes down entire network will go down.
- Network Performance is dependent on central device capability.
| Key Point Here when we are referring to all the nodes connectivity it will be star topology, however, if we consider the connectivity only between node and central device, it will be referred as a point to point. |
Ring Topology
In ring topology nodes/devices are connected with their neighboring device in form of a circle/ring, hence it’s called a ring topology. Each of the node will have two connected neighbors. The data flow in ring topology happens in one direction (unidirectional) by default. But in case we want to make it bi-directional we can set up the dual-link.
In unidirectional data, flow happens in one direction and forms an endless single loop, and has no termination point. This network is referred to as a half-duplex network. This is also referred as a single ring topology.
In bi-directional ring topology, two rings are formed and in this data, flow happens in both directions ( in one ring it will be clockwise and the other will be anticlockwise ) making it a full-duplex network. This is also referred as a dual ring topology.
Advantages of Ring Topology
- Data flow happens is in a circular direction due to which the chance of packet collision gets minimized.
- The ring topology provides very high speed.
- Ring topology provides better performance than bus topology, even when the devices are more.
- Ring topology network is robust & can handle high numbers of nodes/devices.
Troubleshooting in the ring network is much easier because cable faults can be easily located. - Ring network is comparatively less costly than the other topologies such as mesh, hybrid, or tree topology.
Disadvantages of Ring Topology
- single break in the cable can cause disturbance in the entire network
- In Uni-directional Ring, a data packet (token) must pass through all the nodes.
- The addition and removal of any node in a network is difficult and can cause an issue in network activity.
- Ring network is much slower than Ethernet network under normal load conditions.
Mesh Topology
Mesh topology is an arrangement where the nodes and devices are interconnected through multiple connections. Since the node will be having multiple paths to connect this gives network redundancy to each node.
Mesh topology is mainly used in WAN implementation where redundancy is a key concern due to the huge network. In Wireless Network also mesh topology is used. The Internet is one of the best examples of mesh topology. Mesh topology network can be either full mesh or partial mesh. In partial Mesh topology, few nodes will be connected via two-three connections while in Full mesh topology, the number of redundant connections can be Huge.
Advantages of Mesh Topology
- Mesh topology is very stable & reliable as a single breakdown will not make the network down as multiple redundant connections/paths are there.
- Communication is very fast between the nodes.
- The addition of a new device is very easy as it won’t disturb the existing setup.
Disadvantages of Mesh Topology
- Installation and configuration are difficult.
- The cost of a mesh topology network is high as the cabling requirement will be huge due to multiple cabling paths.
- Maintenance cost is high as it contains a large number of connected devices such as a router and more transmission media than other topologies.
- Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.
- In this topology, redundant connections are high that reduces the efficiency of the network.
Tree Network Topology
Tree topology is a combination of the characteristics of bus topology and star topology & inherits properties of bus topology. In tree topology has a hierarchical structure like a tree where the top-most node will know as the root node and below other nodes will be descendants of the root node. This is one of the common forms of network topology in use nowadays.
Advantages of Tree Network Topology
- It’s easily manageable as the network is divided into multiple segments.
- Expansion in a tree topology network is easy as we can easily add new node in the network.
- Troubleshooting is easy in a tree topology network as it can be easily identified and rectified.
Disadvantages of Tree Network Topology
- The entire network is dependent on the health of the root node in a tree topology & if the root node fails then respective node branches will get impacted.
- Cost is one of the factors if this is being considered for WAN implementation.
- If backbone connectivity gets impacted, it will result in a major outage.
Hybrid Network Topology
Hybrid topology is a combination of two or more different topologies. Like the branch of one office is having star topology and another branch is having bus topology and both are connected with Head Office or Data Center for communication.
Hybrid topology is usually found in a larger enterprise setup where multiple departments are there. Based on the requirements different network topologies can be integrated.
Advantages of Hybrid Network Topology
- In a hybrid topology network, scalability is very easy and can be expanded by adding new devices as per requirement.
- As the name says hybrid, it has the flexibility of merging or adapting different topologies in the existing network.
- Reliability is another advantage in hybrid topology as we can consider the best feature of each topology to increase the reliability & enhance the performance
Disadvantages of Hybrid Network Topology
- Complexity gets increased when we design a network in Hybrid topology as multiple different topologies are used.
- Cost becomes another factor as additional cabling & devices are required which should support multiple topologies.
Which is the best network topology ?
There is no specific rule which can define any particular topology as best network topology. But based on the business requirement & other factors one can decide which one is the best suitable topology.
How to decide or choose network topology while setting up a network?
We can choose which topology is the best suitable for our specific setup based on various facgtors. Below are the few key points that can be used to factor.
- Distance
- Cost
- Reliability
- Scalability
- Time required
Ref. : Wikipedia
Frequently Asked Questions
Q. Which LAN topology is best?
A. In current days, star topology is considered to be the most common and easy to setup.
Q.Which topology is used in schools?
A. In school depending on the size of the network, Star topology & hybrid topology are considered most suitable for schools.
Q. What topology does a home network with a single wi-fi router use?
A. In a home where all the computers/devices are connected to Wi-Fi router will be referred as star topology. Here computer can communicate with each other through Wi-Fi router only.
Q. When you connect four computers with one printer which topology is used?
A: It depends how the computers are interconnected.
- If all the four computers are connected to one network switch & printer is connected to one computer and shared with other computers then its star topology.
- If all the four computers are connected in line with other & printer is connected with one computer and shared with other computers then its BUS topology.
- If all the four computers are connected to one network switch & printer is also connected directly to the same switch then also its star topology.
Q. Which topology is the highest reliability?
A. Mesh topology is considered the most reliable topology as it provides multiple redundant path.
Q. What is the central device in star topology?
A. In LAN network, Switch or Hub is will be the central device.
Q. Which network topology is most used today?
A. IN LAN, Star topology is the most commonly used topology.
Q. What is a topology diagram?
A. Topology diagram where we visually represent the devices, their connections, and paths to help us in understanding now nodes are connected and communication is happening with each other.
Q. When you connect four computers with one printer which topology is used?
A. Assuming all four computers & printer is connected to a network Switch, this topology will be called as Star Topology.
Q. What topology does a home network with a single router?
A. Star Topology as at home all the computers/devices will be connected to Wi-Fi router.
Q. What is a network topology in simple words?
Network topology is a structure or pattern defining the connectivity of nodes in the network which helps in managing, maintenance, and expansion of the network. Network topology can be segregated into two – physical topology and logical topology. Various types of topologies are Point to Point, Bus, Ring, Star, Mesh, Tree, and Hybrid.
Q. What is physical and logical network topology?
A. Physical topology refers to the actual connections (wires, cables, etc.) between nodes & their arrangement in the network. Logical topology refers to a high-level view for understanding the design of the network setup, sites, and location of the network.