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Introduction
This blog will mainly discuss all the types of network topologies we have discovered in computer networking. Before jumping on the types of network topologies, let’s first understand what a network is,
A network is a set of devices(often referred to as nodes) connected by communication links.
A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.
A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information.
Network Criteria
A network provided, must be able to meet a certain number of criteria, let’s discuss them one by one,
Performance
Performance depends on the network elements.
It can be measured in terms of transit time and response time.
It is evaluated by two networking metrics: Throughput and Delay.
Reliability
The failure rate of network components measures reliability.
It is measured in terms of availability/robustness.
Security
Data protection against corruption/loss of data due to errors and malicious users.
Physical Structure of a Network
Types Of Connection:
Point to Point Connection:- It is a dedicated link between two devices. These two devices share the capacity of this link. Generally, Point to point connections uses an actual length of wire/cable to connect the two devices. There are other options also, like, microwave links, satellite links, Infrared rays from television remote to television, etc.
Multipoint:- It is a connection in which more than two devices share a single link.
It is the way in which the network is laid out physically. Basically, it is the connection of devices. Two or more devices connect to a link, and two or more links form a topology. A topology in computer networking is a type of arrangement to connect computer systems and network devices.
There are various types of topologies that are possible and they are explained below in the blog.
Mesh Topology
In Mesh topology, each and every device has a dedicated point-to-point link to every other device. Now the term dedicated link means that it will carry the traffic only between the two devices that it connects. In a mesh topology, if there are ‘N’ nodes, then we need the ‘N * (N - 1)’ number of physical links.
Advantages:
The use of dedicated links in mesh topology guarantees that each connection can carry its own data load.
A mesh topology is robust.
There is the advantage of privacy and security.
Fault identification and fault isolation become easy with the help of a Point-To-Point connection.
Links with suspected problems can be avoided after routing the traffic.
Disadvantages:
The bulk of cabling and the total number of I/O ports are required in a mesh topology because each and every device must be connected to every other device, and installation and reconnection are difficult.
The sheer bulk of the wiring in mesh topology can be greater as compared to the available space to accommodate it.
The hardware in mesh topology required to connect each link (I/O ports and cable) can be prohibitively expensive.
Star Topology
In star topology, every device has a dedicated point-to-point link to some central controller, and we call this central controller a hub. These devices are not directly linked to each other, unlike mesh topology. In star topology, no direct traffic between the devices is allowed. In star topology, the hub acts as an exchange.
Advantages:
Star topology is cheaper than mesh topology. Here, each device needs only one link and one I/O port to connect it to any number of others.
Installation and reconfiguration are easy in a star topology. Far less cabling needs to be planted, and additions, moves, and deletions involve only one connection in the star topology: between the device and the hub.
Star topology is robust. If one link fails in the star topology, only that link is affected. All other links remain active.
Easy fault identification and fault isolation.
Disadvantages:
Star topology is dependent on one single point, the hub. If the hub goes down in the topology, the whole system is dead.
Star topology requires far less cable than mesh topology. Each node in star topology must be linked to a given central hub. To accomplish this, often more cabling is required in a star than in some other topologies (such as ring or bus).
Bus Topology
A bus topology is a multi-point connection. A long cable in bus topology acts as a backbone to all the devices in the network. These nodes/devices are connected to the main bus with the help of a drop line and tap. This drop-line is a connection that is running between the device, and the main cable, and this tap is the connector that pierces into the main cable or punctures into the main cable to create contact with the metallic core. There is a limit on the number of taps and the gap between the devices because of the heat generated by the traveling of signal from the single cable that is the main cable.
Advantages:
Bus topology is easy to install.
Bus topology uses less cabling than mesh or star topologies.
Disadvantages:
In a Bus topology, it is difficult to reconnect and fault isolation.
A bus in bus topology is usually designed to be optimally efficient at installation. Therefore, it can be difficult to add new devices.
The signal reflection at the taps in bus topology can cause degradation in quality.
A fault or break in the bus cable stops all the transmissions, even between devices on the same side of the problem.
In a ring topology, every device has a dedicated point-to-point connection with the two devices on either side of it. A signal is passed through the main cable in one direction only. In the ring topology, every device has installed a repeater. Now, when a device receives a signal from another device, it will regenerate the bits and pass the signal.
Advantages:
A ring in a ring topology is relatively easy to install and reconfigure.
Each device in a ring topology is linked to only its immediate neighbors (either physically or logically). In the ring topology, adding or deleting a device requires changing only two connections.
Disadvantages:
Unidirectional traffic in ring topology results as a disadvantage. A break in the ring in the ring topology can disable the entire network.
Tree Topology
In a tree topology, various secondary hubs are connected to a single central hub. This topology is the variation of star topology and is a multi-point connection. In this topology, data is flown from top to bottom with the path from the central hub to secondary hubs and then to the devices.
Advantages:
Tree topology is a combination of star and bus topology.
In tree topology, leaf nodes can contain more devices.
Failure of one node in tree topology will not affect other nodes.
Disadvantages:
In the tree topology, we need a large number of cables as compared to ring or star topology.
Implementation cost is high.
The network performance of tree topology is slightly slower because of the large number of nodes.
Hybrid Topology
A network can also be implemented in a hybrid way. In hybrid topology, we use two or more types of network topologies to implement a network. We can make a mixture of bus, mesh, star, and tree topologies all together to create a network.
Advantages:
Hybrid topology can be modified as per requirements.
We can get the advantages of different types of topologies in this hybrid topology.
Hybrid topology can handle a large amount of traffic.
Hybrid topology is mainly used to create large networks.
Disadvantages:
Hybrid topology is network expensive.
It has a complex design.
Installation of hybrid topology is a difficult process.
Lots of cables are required in the installation of hybrid topology.
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