What is Computer Network? Defination &Types of Computer Network.

 

What is Computer Network? Defination &Types of Computer Network.

A computer network is a system of interconnected computers that enables computers to communicate with each other and share their resources, data, and applications. The physical location of each computer is more for personal and organizational needs. A network may include only personal computers or a mix of PCs, minis, and mainframes spread over a specific geographic area. Computer networks that are commonly used today can be classified as follows:

Based on geographic area:

1. Local Area Network (LANS)
2. Wide Area Network (WANS)
3.Metropolitan Area Networks (MANs)
4. International Network (Internet)
5. Intranet

Based on how the computer node is used:

1.Client Server Networks (CSNs)
2. Peer-to-Peer Networks (PPNs)
3. Value Added Network (VAN)

 

Local Area Network (LAN)
A LAN is a group of computers, as shown in Figure 14.4, that are connected in a small area such as building a house. LAN is generally used to connect two or more personal computers through some medium like twisted pair, coaxial cable etc. Although the number of computers connected to a LAN is limited, data is transferred at extremely high speeds.

Wide Area Network (WAN)

A WAN is a group of computers connected over a large area such as a continent, country, etc. WAN is generally used to connect two or more LANs such as leased telephone lines, microwaves, etc. Data is transferred over the WAN. in slow motion.

Metropolitan Area Network (MAN)
A MAN is a network of computers covering an area as large as a city. The size of MAN is usually between LAN and WAN, usually covering a distance of 5 Km to 50 Km. Geographical area covered by MAN is relatively larger than LAN but smaller than WAN. MAN is usually owned by private companies. MAN is usually connected by means of optical fiber, copper wire etc. The most common example of a MAN is the cable television network within a city as shown in Figure 14.6. A network device known as a router is used to connect LANS together.

Internet
The Internet is a global area network that allows computers connected through a network to share resources and information using various protocols. It is essentially a network of networks worldwide. Users in different locations can easily communicate with each other through the Internet. They can access data and information from other computers if they are allowed to do so. The Internet basically uses a set of protocols such as Transmission Control Protocol/Internet Protocol (TCP/IP) to transfer data over the network. Following are the various services provided to internet users:

E-mail: E-mail is a widely used service on the Internet through which users can send and receive messages in an efficient manner. It allows one person to send messages even if the other person is offline. E-mail messages are sent from a unique e-mail address. A series of characters in the form of username@hostname to send a message to a person is known as an e-mail address.

• Online ChatOnline chat usually allows one-to-one communication between individuals over the Internet. Users can communicate directly with fellow friends there by sending and receiving messages. Online chat is only possible when both sender and receiver are online.

• Online Shopping Internet has become popular through online shopping of various products. Now, it is very easy and simple to buy products from other parts of the country or anywhere in the world. A user can purchase an item using a personal computer, the Internet and specialized software such as shopping carts and e-cash. Shopping cart is used to select items online while e-cash is used for online payment of purchased items.

• Usenet Usenet is an Internet-based newsgroup that allows individuals to share their opinions about a particular subject or topic over a network. People accessing Usenet can receive these comments via private or public e-mail.
There are various advantage of using the Internet:

• Information Internet allows users to access large amounts of information efficiently. Information can be related to any subject, such as law, marketing, finance, science, technology, etc.

• Availability Continuously available to internet users without any delay. Users can access information anytime from the internet.

• Cost Internet provides various benefits to users at low cost. Users can access any website over the internet completely free. Sending messages via e-mail is also cheaper than postal messages

Following are some disadvantages of internet usage:

• Hacking The process of illegally accessing personal information stored on the Internet is called hacking. A person who engages in this activity is called a hacker.

A virus is a software program that activates itself in our computer system and destroys the stored data. Viruses usually infect resources connected to the Internet.

. Bulk E-mail This is one of the most common problems in the Internet where users receive unwanted bulk messages such as subscription mails, advertisement mails, job alert mails etc. in their accounts. These messages are sometimes frustrating and annoying for the users because the user simply does not need these mails.

Intranet
An intranet is a private network, limited to only one organization. This type of organization allows only internal users to share resources. However, users outside the computer network organization can also access the intranet but only if they are authorized to do so. The concept of intranet was used to share company information among employees. Certain protocols such as TCP/IP, HTTP, etc. are used by intranets to enable communication between computer systems. Organizations that use intranets to transfer messages typically use tunneling, a technique used to send private messages. Intranet websites are protected by firewalls. which is a layer that helps ensure the security of information and resources. The only disadvantage of intranet is that it is relatively insecure compared to other networks. Following are the various advantages of using intranet:

It allows employees of an organization to access company information easily and quickly.
• Intranet users can easily communicate with each other within the organization.

• Intranets are relatively easier to maintain and implement than the Internet.

 

Client Server Network (CSN)
CSN basically formation  of two computers, client computer and server computer. Client computers are dummy computers, which only send requests to server computers, whereas server computers receive them in a client-server architecture.
This architecture is a two-tier architecture, which is divided into two levels. The first layer consists of the user interface located on the client's desktop. On the other hand, the second layer is the database management layer, which is located on the server machine to provide services to the clients. In CSN, a client computer sends a request for data processing to the server. The server receives requests from client computers and processes the data. It sends the output obtained after processing the data to the client computer in response to its request. Benefits of CSN are as follows:

★ There is a proper distribution of computing work. The client computer's job is to send requests to the server for data processing. The server receives the client computer's request, processes the data, and sends the result back to the client computer.

★All important information is stored on the server and only authorized persons are allowed to access the data from the server. As a result, data in a CSN has greater security.
   ★ Data updates are easy to manage as data is stored in a centralized manner on a server.

★Multiple client computers of different hardware configurations are able to interact
with a server.
Following are the disadvantages of CSN:
★ When the server crashes, the entire network breaks down.

★ Server load on a CSN increases as multiple clients send some requests to a server. As a result, network traffic increases and network congestion occurs.

Peer-to-Peer Network (PPN)

In PPN, there is no separate category as client and server. Every computer in the PPN is treated equally and can send and receive messages directly. PPN architecture cannot work under heavy load.Computers connected to this network can easily share their resources with other computers PPN is used in various fields like business, education, telecommunication, military etc. The advantages of PPN are as follows: • PPN is relatively cheaper than CSN, as centralized servers are not required.

• PPN is simpler than CSN because computers connected to the network can communicate with each other efficiently.

Disadvantages of PPN are as follows:

• PPN is less secure because messages flow freely between computers.

• PPN is decentralized because there is no fixed location for storing files.

• PPN is less expandable because network performance and speed decrease when more computers are added.

Value Added Network (VAN)
VAN is a network typically used by companies privately for Electronic Data Interchange (EDI), a standard used for exchanging business data. In other words, a WAN is a network that adds value to the information transmitted, usually by providing value-added services. An example of a value-added service would be the conversion of data in Extensible Markup Language (XML) to EDI provided to certain companies through VAN.

In addition to providing value-added services, VAN also provides automatic error detection and correction and protocol conversion services for data changes. Error detection and correction is a technique used to detect and then correct errors in transmitted data. On the other hand, protocol conversion is basically used to convert a message, which has been transferred using a particular protocol to another protocol with the help of a protocol converter.

FAQ

  
What are the 4 types of networks?
1.Personal Area Network (PANS)
2. Local Area Network (LANS)
3. Wide Area Network (WANS)
4.Metropolitan Area Networks (MANs)