Computer Networking has seen significant evolution, especially in the last 10years. In the late 1950s, the computers were considered as huge complex machines and are operated by trained people. But now, things have changed, and advanced technologies have come into existence. Even a small kid can connect with the world to explore new technology using Computer Networks. It has evolved to be a user-friendly device, and that made things very easy for the users to understand the behaviour of Computer Networks. 

What is Computer Networking?

A computer network is a set of two or more interlinked computer systems through a wired or wireless media to send or receive data. It is a digital telecommunication network that allows the nodes to allocate resources. Every network involves hardware and software that connects computers and tools. Multiple devices help in communication between two or more different devices which are known as Network devices such as Router, switch, hub, bridge, etc.

A Computer Network is not only to meet the connectivity between the computers to share data but also it has to meet the network criteria such as 

Performance: It can be measured with two terms one is Transmit time is a time taken for a message to travel from one device to another, and the other is Response time which is the elapsed time between query and response. The performance depends on the following factors:

• Type of transmission medium used.
• Number of users
• The efficiency of software, and
• The capability of connected network

Reliability: It is measured in terms of

• Recovery from failures
• Frequency of failures
• Robustness during disaster

Security: It has to ensure data from unauthorized access. When the data is flowing in a network, it has to flow through various network layers. So, it has a chance of data breach by unwanted users. That is why Data security is the most crucial part of the Computer Network.

Basics of Computer Network

The Computer Network components consist of both hardware devices and the software devices that are required to install. There are a few essential Computer Network components that are discussed below:

• Servers: The server is a computer that handles the shared files, programs, and the network operating system. It allows access to network resources for all the users in the network.
• Routers: A route is networking devices that enable to share a single internet connection with multiple devices, thus saves money.
• Switches: Switches works as a controller that connects computers, printers, and other hardware devices to a network.
• Modem: It allows the computers to connect with the network over a telephone line.
• Transmission media: It is a carrier used to interconnect computers in a network through cables and connectors such as twisted pair cable, coaxial cable, and fibre optic cable.
• Hub: It is a device that splits the network connection into multiple computers.  

Goals of Computer Network

Computer Network is a means of interconnection of computers for sharing the data through the network from person to person. There are a few essential goals of the Computer Network. They are as follows:

• Flexibility: Easy access to sharing data from any computer on the network.
• High reliability: If there is an external source of supply, all the files should make a copy on two or more machines. If any of them gets troubled with some hardware issues, the other copies can be used. 
• Resources sharing: In an organization, numerous computers are working and located apart. E.g. A group of workers can share an ordinary scanner, modem, printer, etc.
• Inter-process communication: It is a mechanism that allows processes to communicate with each other and synchronize their actions. It is used for exchanging data between multiple threads.

Apart from these goals, it also includes excellent network performance, scalability, centralized management, access to remote information, etc.

Basic Communication model

Over several years ago, the basic communication model has been evolved that represents various elements of communication processes. They are as follows:

• Sender: The person or an organization that has information to share with other person or an organization
• Message: A message is data or information to be delivered
• Medium: It is a channel through which the communication travels from sender to receiver
• Receiver: The person who receives the message sent by the sender
• Noise: It refers to a factor that can interface with adequate comprehension. It occurs when the message or the data subject to noise
• Feedback: It is a part of the receiver’s response that communicates back to the sender

This model supports all kinds of data, such as text, voice, or even a video. It is very fast and takes a fraction of a second to communicate the message, and yet it provides a highly secured medium of communication; thus, it was easy to access.

Line configuration of Computer Network

Line configuration refers to the way of connecting two or more communication devices through a link. A link is a communication pathway that sends data from one device to another. The devices can be a PC, Laptop, printer, etc. that can send and receive data. To connect with the devices, they are two methods to follow:

• Point-to-point Connection
• Multipoint Connection

Point-to-point Connection: The point-to-point is a convention that is used as a communication link between two devices. It is easy to establish and understand. The point-to-point connection uses an actual length of wire to connect the two devices, or the other satellite links are also possible. It is considered to be the most straightforward and conventional network topology.

E.g., The Point-to-point connection between Television and the remote to control the Television.

Multipoint Connection: It is used to connect two or more devices with a single shared link. It is also called the Multidrop configuration. It has the capability of sharing the link with more than two devices. Depending on that capacity, the ways of configuration are of two kinds. They are discussed below:

• Spatial sharing: If a link is used between many devices concurrently, then it is known as Spatial shared configuration
• Temporal sharing: If the user takes turns while using the link, then it is known as Temporal shared line configuration.

Types of Transmission Media

In network communications, the Transmission Media is a Physical connection or interface between a Transmitter and a Receiver. It is the channel through which data is transferred from one place to another. Transmission Media are classified into two types. They are discussed below:

Guided Media: It provides a conductor from one device to another and transmits signals through the cables that are directed and confined by the physical limits of the medium. It is also known as Bounded or Wired Transmission Media. It provided a high-speed transmission of data, Comparatively used for shorter distance cable connectors, and even more secure. There are three types of Guided Media. They are as follows:

• Twisted Pair Cable: These are widely used medium in networking because of its low cost, lighter, easy to fix and replace, and provides high speed than coaxial cables. Again these Twisted pair cables are of two types. They are
• Unshielded Twisted Pair: It has a four pair of copper wires that are present within a plastic sheath. The wires are twisted to avoid interference. It is widely used in telephonic applications. It provides a high-speed capacity with low cost and easy to fix the cable.
• Shielded Twisted Pair: It was widely used in high-speed networks. It makes the use of a metallic shield to wrap the wires to prevent interference better than UTP. It is highly expensive and provides better performance. It is used in voice and data channels of telephone lines.
• Coaxial cable: It consists of three layers for a central copper conductor surrounded by an insulating layer, a conducting shield and an outermost plastic jacket. There are two basic modes of data transmission in Coaxial cable. One is the broadband mode that has a distributed cable bandwidth, and the other is the baseband mode that has a dedicated cable bandwidth. It was mainly used in televisions and Cable TV. It provides high bandwidth with reasonable cost and easy to install. 
• Optical fibres: It uses the concept of light waves through a core made of glass or plastic. These cables are well suited for video, voice or data transmission. Optical fibres are the most secure of all the cable media and have excellent transmission speed, a signal can travel a longer distance when compared with other cables, and provides high bandwidth. Difficult to install and maintain and even expensive, but it can withstand electromagnetic interference.

Unguided Media: It has no visible medium that is used for the transmission of signals. The signals are broadcast through the air that was the only medium and can be used for long-distance communication. It was also known as Wireless or Unbounded transmission media. These are of three types. They are as follows:

• Radio Waves: These are easy to generate, and the frequency range is between 3KHz-1GHz. These waves are widely used for the transmission in AM and FM radio and cordless phones. 
• Microwaves: It is a line of sight transmission that means the sending and receiving antennas are required to align appropriately with each other. The distance covered by the signal is directly proportional to the height of the antenna. And the frequency range is between 1GHZ-300GHz. These are commonly used for television distribution and mobile phones.
• Infrared waves: It is used for short-distance communication, and it cannot penetrate through obstacles. The frequency range is between 300GHz-400THz. These are used in a wireless mouse, printer, keyboard, TV remote, etc.

Transmission modes in Computer Network

The Transmission mode refers to the mechanism of transferring the data between two devices connected over a network. It directs the flow of information. It was also known as Communication mode. These modes are of three types. They are:

Simplex mode: It is a unidirectional communication system that means the data can be sent only in one direction. We cannot send a message back to the sender.

Example: Loudspeaker, Television, Monitor, Keyboard, etc.

Half Duplex mode: It is a Bidirectional communication system that a data can be transmitted in both directions but not at the same time. That means when one device is sending, the other can only receive at that time, and vice versa. 

Example: The best example for Half Duplex mode is the Walkie-talkie in which the message can be transmitted in both the direction one at a time.

Full Duplex mode: The Full-Duplex mode is as same as Bidirectional communication. We can transmit and receive the data in both the directions simultaneously. In this system, there can be two lines, one for sending the data and the other for receiving the data.

Example: Telephone Network in which there is communication between two persons by a telephone line that can talk and listen at the same time.

Types of Area networks

The Geographical area that a network covers to connect and communicate with all the different computers through a medium. There are various types of Computer Networks are categorized depending on their capacity of the area covered and the numbers of systems connected in the network. 

The most widely used Area Networks are 

• Local Area Network(LAN) 
• Metropolitan Area Network(MAN)
• Wide Area Network(WAN). 

Apart from these types, there are other types of Computer Networks also like 

• Personal Area Network(PAN) 
• Storage Area Network(SAN)
• Enterprise Private Network(EPN)
• Virtual Private Network(VPN)

Local Area Network(LAN): A group of computers and devices are connected in a limited area such as Office building, School, etc. This type of network can connect 5000 interconnected devices across the building. It covers a small geographical area that limits to a few kilometres and is owned privately. It was easy to maintain, and the error and noise are minimal due to the short distance network. 

Metropolitan Area Network(MAN): It covers a larger geographical area than LAN and serves as an Internet Service Provider(ISP). It provides high-speed connectivity and covers over a 50km geographic range like towns and cities. The data rate is adequate for distributed computing applications. 

Wide Area Network(WAN): It covers over a large geographical area and is confined within the boundaries of the state or country. The WAN connects with LAN by linking to other LAN’s through telephone lines and radio waves and thus limited to an organization or a company to be accessible to the public. 

Types of Network Topologies

The arrangement of a network that comprises nodes and connecting lines through sender and receiver is known as network topology. Various kinds of Network Topologies are discussed below:

Bus Topology: It is a kind of network in which every computer and network device is connected to a single cable and transmits data only in one direction. It is easy to understand and requires very less cable when compared to other topologies. It is used to build small networks. The nodes are connected to the channel through drop lines.

Star Topology: In this kind of topology, all the systems are connected to a single network device through the cables. The network device can be a Hub, server, router, or switch the network devices acts as a central node that connects all the systems. High cost but easy to maintain. If the one system fails, the whole network doesn’t interrupt, but if the central node fails, the entire system gets interrupted.

Mesh Topology: In this mesh topology, every system is connected to another system through a specific channel. There are two ways to transfer data over Mesh topology. One is routing, which is the nodes accompany a routing logic according to the network required to guide the data from source to destination. The other method is flooding, which is the same data is transmitted to all the nodes of the network, and hence it has no logic. The network is robust in case of flooding, and it is hard to lose any data. It was an expensive and highly secure network. It also detects the faults very easily.

Ring Topology: In this ring topology, each computer is connected to another computer in the form of a ring that connects the last system to the first system. It is a unidirectional data flow system, but, with the use of the dual connection, it can also be used for bidirectional data flow. It was easy to install and expand and used for transmitting huge data traffic. 

Tree Topology: It consists of one root node that connects all the sub-nodes in the form of tree representations. In general, it has three levels of hierarchy, and it expands depending on the requirement. It detects faults quickly and easy to maintain.

Hybrid Topology: It is the combination of two or more topologies. These topologies can be a mix of Bus topology, Mesh topology, Star topology, Tree topology and Ring topology. The use of Hybrid topology depends on the requirement of business, users, etc. It is scalable and reliable at the same time it is the most expensive among all other Topologies.

Applications of Computer Networks

Following are some of the business applications of computer networks:

Sharing Resources: The main aim of Computer networks is to make all the programs, data, devices, available to everyone on the network irrespective of the location of the resources and the user.

Communication Medium: Computer networks provide a reliable setup of communication medium among the employees in an office. Every organization will have two or more computers using an e-mail function that all the employees are used for day-to-day communication.

Server-client model: Imagine a system in which a firm’s data is stored on a system that is highly secured with firewalls and is situated in the company office. A person who works in that organization needs to access data remotely with the desktop. In this model, the data is stored on computers in the firm called servers, and the employee desktop will be the Client.

E-commerce: Doing business with consumers over the internet has become an essential goal in e-commerce. Online shopping, online library, online trading, and many more were come under E-commerce and thus expected to grow in future to a great extent. It is the most convenient way of dealing with things and even saves time and money.

Advantages of Computer Network

Let’s see the main advantages of Computer networks: 

Data storage: Data can be stored in the server that can be shared and available to every user in the organization

Highly flexible: It offers users the opportunity to explore everything about computer networks such as software without affecting their functionality.

Cost efficiency: with the use of computer networks, you can use a lot of software products available in the market that can be installed into your system or server.

Data backup: Due to some damage to the devices or the system, the data can get inaccessible on one PC, another duplicate of similar data is accessible on another system for future use. So backing up the data helps in further handling without interruption.

Increases storage capacity: The shared data, files, and resources have to ensure that the data is properly stored in the system. With the help of Network technology, you can get the required data space to store.

Disadvantages of Computer Network

The disadvantages of Computer Network are as follows:

• Security issues: Lots of people share the network to transmit and receive data, so an individual user’s security will be at stake. Lack of security leads to Data breach.
• Lack of robustness: If the main server breaks down, the entire system will become interrupted. Also, if the central linking server fails, the whole network gets distracted. 
• Presence of virus and malware: If the system infected with a virus, then the data in the system gets corrupted. So the regular inspection has to be done to ensure safe Data storage in the system.
• Expensive setup: Cost of installation depends on the number of systems to be connected in the network. Use of costly devices such as servers, routers, hubs, etc. adds cost and also requires the Network Interface Cards for the workstations.

Conclusion

In this tutorial, we have learned all the necessary and core concepts of Computer Networks that results in better performance with high speed of processing. We have learned Types of transmission model, Configuration lines, Types of Area networks, Network Topologies, and Applications of Computer Network.