Introduction to Computer Networks

A computer network is a group of computers linked to each other that enables the computer to communicate with another computer and share their resources, data, and applications.

A computer network can be categorized by their size. A Computer Network is mainly of four types:

1. LAN (Local Area Network)
2. PAN (Personal Area Network)
3. MAN (Metropolitan Area Network)
4. WAN (Wide Area Network)

1. LAN (Local Area Network)

Local Area Network is a group of computers connected to each other in a small area such as a building, office. LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc.

• It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables.
• Data is transferred at an extremely faster rate in Local Area Network.
• Local Area Network provides higher security.

2. PAN (Personal Area Network)

Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters.

• Range: Covers an area of 30 feet.
• Devices: Laptops, mobile phones, media players, and play stations.

Thomas Zimmerman was the first research scientist to bring the idea of the Personal Area Network. Personal computer devices that are used to develop the personal area network are the laptop, mobile phones, media player and play stations.

Types of Personal Area Network

1. Wired Personal Area Network: Created using USB.
2. Wireless Personal Area Network: Developed using wireless technologies such as Wi-Fi, Bluetooth. It is a low range network.

Examples of Personal Area Network

1. Body Area Network: A network that moves with a person. For example, a mobile network moves with a person.
2. Offline Network: Created inside the home, so it is also known as a home network. A home network is designed to integrate devices such as printers, computers, television but they are not connected to the internet.
3. Small Home Office: Used to connect a variety of devices to the internet and to a corporate network using a VPN.

3. MAN (Metropolitan Area Network)

A Metropolitan Area Network covers a larger geographic area by interconnecting different LANs to form a larger network. Government agencies use MAN to connect to the citizens and private industries.

• In MAN, various LANs are connected to each other through a telephone exchange line.
• The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN, OC-3, ADSL, etc.
• It has a higher range than Local Area Network (LAN).

Uses of Metropolitan Area Network

1. Communication between banks in a city.
2. Airline Reservation.
3. Colleges within a city.
4. Military communication.

4. WAN (Wide Area Network)

A Wide Area Network extends over a large geographical area such as states or countries. It is a larger network than LAN and not limited to a single location. It spans over a large area through telephone lines, fiber optic cables, or satellite links.

• Examples: Internet, Mobile Broadband (4G), Last Mile connections, Private Networks.
• Uses: Business, government, and education.

Advantages of Wide Area Network

1. Geographical Area: Provides a large geographical area. Suppose if the branch of our office is in a different city then we can connect with them through WAN.
2. Centralized Data: Data is centralized, reducing the need for multiple servers.
3. Get Updated Files: Software companies work on live servers, ensuring updated files.
4. Exchange Messages: Messages are transmitted fast via web applications like Facebook, WhatsApp, Skype.
5. Sharing of Software and Resources: We can share software and resources like hard drives, RAM.
6. Global Business: Enables global business operations.
7. High Bandwidth: Leased lines provide high bandwidth, increasing productivity.

Disadvantages of Wide Area Network

1. Security Issue: More security issues compared to LAN and MAN.
2. Needs Firewall and Antivirus Software: Protection against hackers and viruses.
3. High Setup Cost: Installation cost is high due to routers and switches.
4. Troubleshooting Problems: Difficult to fix problems over large areas.

Internetwork

An internetwork is defined as two or more computer network LANs or WANs or computer network segments connected using devices and configured by a local addressing scheme. This process is known as Internetworking.

• Uses: Public, private, commercial, industrial, or government networks.
• Protocols: Internet Protocol (IP).
• Model: Open System Interconnection (OSI).

Types of Internetwork

1. Extranet: A communication network based on internet protocols. Access is restricted to users with login credentials.
2. Intranet: A private network based on internet protocols. Accessible only by an organization’s employees.

Advantages of Intranet

1. Communication: Provides cheap and easy communication.
2. Time-Saving: Real-time information sharing saves time.
3. Collaboration: Facilitates collaboration among employees.
4. Platform Independency: Neutral architecture compatible with different devices.
5. Cost-Effective: Reduces the cost of data distribution.