Introduction to Computer Networks

 What is a Computer Network?

• Computer Network is a group of computers connected with each other through wires, optical fibers, or optical links so that various devices can interact with each other through a network.
• The aim of the computer network is the sharing of resources among various devices.
• In the case of computer network technology, there are several types of networks that vary from simple to complex level.

 

Components of Computer Network:

The major components of a computer network are:

NIC (National interface card)

NIC is a device that helps the computer to communicate with another device. The network interface card contains the hardware addresses, and the data-link layer protocol uses this address to identify the system on the network so that it transfers the data to the correct destination.

There are two types of NIC: wireless NIC and wired NIC.

• Wireless NIC: All modern laptops use the wireless NIC. In Wireless NIC, a connection is made using the antenna that employs radio wave technology.
• Wired NIC: Cables use the wired NIC to transfer the data over the medium.

Hub: Hub is a central device that splits the network connection into multiple devices. When a computer requests information from a computer, it sends the request to the Hub. Hub distributes this request to all the interconnected computers.

Switches: A switch is a networking device that groups all the devices over the network to transfer the data to another device. A switch is better than Hub as it does not broadcast the message over the network, i.e., it sends the message to the device for which it belongs to. Therefore, we can say that switch sends the message directly from source to the destination.

Cables and connectors: A cable is a transmission media that transmits the communication signals. There are three types of cables:

• Twisted pair cable: It is a high-speed cable that transmits the data over 1Gbps or more.
• Coaxial cable: Coaxial cable resembles like a TV installation cable. Coaxial cable is more expensive than twisted pair cable, but it provides the high data transmission speed.
• Fibre optic cable: Fibre optic cable is a high-speed cable that transmits the data using light beams. It provides high data transmission speed as compared to other cables. It is more expensive as compared to other cables, so it is installed at the government level.

Router: Router is a device that connects the LAN to the internet. The router is mainly used to connect the distinct networks or connect the internet to multiple computers.

Modem: Modem connects the computer to the internet over the existing telephone line. A modem is not integrated with the computer motherboard. A modem is a separate part on the PC slot found on the motherboard.

 

Uses of Computer Network

• Resource sharing: Resource sharing is the sharing of resources such as programs, printers, and data among the users on the network without the requirement of the physical location of the resource and user.
• Server-Client model: Computer networking is used in the server-client model. A server is a central computer used to store the information and maintained by the system administrator. Clients are the machines used to access the information stored in the server remotely.
• Communication medium: Computer network behaves as a communication medium among the users. For example, a company contains more than one computer has an email system which the employees use for daily communication.
• E-commerce: Computer network is also important in businesses. We can do the business over the internet. For example, amazon.com is doing their business over the internet, i.e., they are doing their business over the internet.

 

Features of Computer network

A list of Computer network features is given below.

• Communication speed
• File sharing
• Back up and Roll back is easy
• Software and Hardware sharing
• Security
• Scalability
• Reliability

Communication speed: Network provides us to communicate over the network in a fast and efficient manner. For example, we can do video conferencing, email messaging, etc. over the internet. Therefore, the computer network is a great way to share our knowledge and ideas.

File sharing: File sharing is one of the major advantage of the computer network. Computer network provides us to share the files with each other.

Back up and Roll back is easy: Since the files are stored in the main server which is centrally located. Therefore, it is easy to take the back up from the main server.

Software and Hardware sharing: We can install the applications on the main server, therefore, the user can access the applications centrally. So, we do not need to install the software on every machine. Similarly, hardware can also be shared.

Security: Network allows the security by ensuring that the user has the right to access the certain files and applications.

Scalability: Scalability means that we can add the new components on the network. Network must be scalable so that we can extend the network by adding new devices. But, it decreases the speed of the connection and data of the transmission speed also decreases, this increases the chances of error occurring. This problem can be overcome by using the routing or switching devices.

Reliability: Computer network can use the alternative source for the data communication in case of any hardware failure.

Goals of Computer Networks

The following are some important goals of computer networks:

Resource Sharing: Many organization has a substantial number of computers in operations, which are located apart. Ex. A group of office workers can share a common printer, fax, modem, scanner etc.

High Reliability: If there are alternate sources of supply, all files could be replicated on two or, machines. If one of them is not available, due to hardware failure, the other copies could be used.

Inter-process Communication: Network users, located geographically apart, may converse in an interactive session through the network. In order to permit this, the network must provide almost error-free communications.

Flexible access: Files can be accessed from any computer in the network. The project can be begun on one computer and finished on another.

Other goals include Distribution of processing functions, Centralized management, and allocation of network resources, Compatibility of dissimilar equipment and software, Good network performance, Scalability, Saving money, Access to remote information, Person to person communication etc.,

 

Computer Networks Applications

Business Applications: Following are some business applications of computer networks:

1. Resource Sharing: The goal is to make all programs, equipment’s (like printers etc), and especially data, available to anyone on the network without regard to the physical location of the resource and the user.

2. Server-Client model: One can imagine a company's information system as consisting of one or more databases and some employees who need to access it remotely. In this model, the data is stored on powerful computers called Servers. Often these are centrally housed and maintained by a system administrator. In contrast, the employees have simple machines, called Clients, on their desks, using which they access remote data.

3. Communication Medium: A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail), which employees generally use for a great deal of daily communication

4. eCommerce: A goal that is starting to become more important in businesses is doing business with consumers over the Internet. Airlines, bookstores and music vendors have discovered that many customers like the convenience of shopping from home. This sector is expected to grow quickly in the future.

Home Applications: Some of the most important uses of the Internet for home users are as follows:

·         Access to remote information

·         Person-to-person communication

·         Interactive entertainment

·         Electronic commerce

 

Categories of Computer Network

A computer network is a group of computers connected with each other through a transmission medium such as cable, wire etc. In this guide, we will discuss the types of computer networks in detail.

Types of Computer Network: There are mainly three types of computer networks based on their size:

1. Local Area Network (LAN)

2. Metropolitan Area Network (MAN)

3. Wide area network (WAN)

1. Local Area Network (LAN)

1. Local area network is a group of computers connected with each other in a small places such as school, hospital, apartment etc.

2. LAN is secure because there is no outside connection with the local area network thus the data which is shared is safe on the local area network and can’t be accessed outside.

3. LAN due to their small size are considerably faster, their speed can range anywhere from 100 to 100Mbps.

4. LANs are not limited to wire connection, there is a new evolution to the LANs that allows local area network to work on a wireless connection.

2. Metropolitan Area Network (MAN)

MAN network covers larger area by connections LANs to a larger network of computers. In Metropolitan area network various Local area networks are connected with each other through telephone lines. The size of the Metropolitan area network is larger than LANs and smaller than WANs(wide area networks), a MANs covers the larger area of a city or town.

3. Wide area network (WAN)

Wide area network provides long distance transmission of data. The size of the WAN is larger than LAN and MAN. A WAN can cover country, continent or even a whole world. Internet connection is an example of WAN. Other examples of WAN are mobile broadband connections such as 3G, 4G etc.

Advantages of WAN:

Centralized infrastructure: One of the main advantage of WAN is the that we do not need to maintain the backup and store data on local system as everything is stored online on a data centre, from where we can access the data through WAN.

Privacy: We can setup the WAN in such a way that it encrypts the data that we share online that way the data is secure and minimises the risk of unauthorized access.

Increased Bandwidth: With the WAN we get to choose the bandwidth based on the need, a large organization can have larger bandwidth that can carry large amount of data faster and efficiently.

Area: A WAN can cover a large area or even a whole world though internet connection thus we can connect with the person in another country through WAN which is not possible is other type of computer networks.

Disadvantages of WAN:

Antivirus: Since our systems are connected with the large amount of systems, there is possibility that we may unknowingly download the virus that can affect our system and become threat to our privacy and may lead to data loss.

Expensive: Cost of installation is very high.

Issue resolution: Issue resolution takes time as the WAN covers large area, it is really difficult to pin point the exact location where the issues raised and causing the problem.

PAN(Personal Area Network)

Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters. Personal Area Network is used for connecting the computer devices of personal use is known as Personal Area Network. Thomas Zimmerman was the first research scientist to bring the idea of the Personal Area Network. Personal Area Network covers an area of 30 feet. Personal computer devices that are used to develop the personal area network are the laptop, mobile phones, media player and play stations.

Interconnection of Networks:

We have read LAN, MAN and WAN above, we also talked about internet. You can say that an internet is a combination of LAN, MAN and WAN.