UNIT 3 : Internet: Overview, Architecture, Functioning, Basic Services

 

Internet: Overview, Architecture, Functioning, Basic Services

Overview of the Internet:

The Internet is a global system of interconnected computer networks that communicate using standard protocols, primarily the Internet Protocol (IP) and Transmission Control Protocol (TCP). It allows for the exchange of data and resources between devices, including computers, smartphones, and various other connected devices. The Internet has revolutionized communication, commerce, education, and entertainment.

Architecture of the Internet:

The Internet's architecture is structured in layers to manage the flow of data and services:

1. Physical Layer:
   • This includes the hardware components such as routers, switches, fiber optic cables, wireless signals, etc.
2. Data Link Layer:
   • This layer is responsible for the error-free transmission of data between devices connected to the same physical medium.
3. Network Layer (IP Layer):
   • The Internet Protocol (IP) operates at this level, ensuring that data packets are routed and delivered between devices, across networks.
4. Transport Layer:
   • This layer is responsible for ensuring reliable data transfer between devices. The Transmission Control Protocol (TCP) is used for error checking and data flow control. For faster, less reliable transmission, User Datagram Protocol (UDP) is used.
5. Application Layer:
   • The topmost layer where end-user services reside. Protocols such as HTTP, FTP, SMTP, DNS, etc., operate here to provide the final services to users.

Functioning of the Internet:

The functioning of the Internet involves multiple components working together to enable communication and data sharing:

1. Data Transmission:

   • Data on the Internet is broken down into small packets. These packets contain the destination IP address, which ensures that the data reaches the correct location.
   • Routers and switches direct the packets through the most efficient path to the destination.

2. IP Addressing:

   • Every device connected to the Internet is assigned a unique IP address that acts as its identifier in the global network.
   • IPv4 and IPv6 are the two versions of IP addresses. IPv6 is the newer version designed to provide more address space.

3. Domain Name System (DNS):

   • DNS translates user-friendly domain names (like www.google.com) into IP addresses that computers understand.

4. Web Browsing:

   • Users access the Internet via web browsers (e.g., Chrome, Firefox), which retrieve web pages using the HTTP (Hypertext Transfer Protocol).

Basic Services on the Internet:

1. World Wide Web (WWW):

   • The WWW is a vast collection of interlinked hypertext documents accessed through the Internet using web browsers. It is based on the HTTP protocol.
   • Users can access text, images, videos, and other multimedia content hosted on web servers.

2. File Transfer Protocol (FTP):

   • FTP is a protocol used to transfer files between computers over the Internet. It allows for the downloading and uploading of files between a client (user) and a server.
   • Types of FTP:
     • Active FTP: Initiates a connection from the server to the client.
     • Passive FTP: Initiates the connection from the client to the server (more commonly used in firewalls).

3. Telnet:

   • Telnet is a network protocol that allows users to remotely access and manage devices over the Internet or a local network. It provides a text-based command-line interface to control servers or routers.
   • It is considered insecure and has largely been replaced by more secure protocols like SSH (Secure Shell).

4. Gopher:

   • Gopher was an early Internet protocol for organizing and distributing documents and information, pre-dating the WWW. It was text-based and primarily used to browse directories of files.
   • It has been largely replaced by HTTP and the WWW.

5. Search Engines:

   • Search engines like Google, Bing, and Yahoo index the vast amount of content available on the web, allowing users to search for information quickly using keywords.
   • They use algorithms to rank pages based on relevance, backlinks, and other factors.

6. E-mail:

   • E-mail is a method of exchanging digital messages between users over the Internet. It typically includes an email address, subject, body text, and attachments.
   • Common protocols for email are SMTP (Simple Mail Transfer Protocol) for sending messages, and POP3 (Post Office Protocol) or IMAP (Internet Message Access Protocol) for retrieving messages.

7. Web Browsers:

   • A web browser is a software application used to access and display content from the Internet, including websites, videos, and multimedia.
   • Popular browsers include Google Chrome, Mozilla Firefox, Microsoft Edge, and Safari.
   • Browsers use HTTP/HTTPS to request and receive data from web servers and present it to users.

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Internet of Things (IoT): Definition, Sensors, Features, Smart Cities, and Industrial IoT

Definition of IoT:

The Internet of Things (IoT) refers to the network of physical objects (devices, vehicles, appliances, etc.) that are embedded with sensors, software, and other technologies, enabling them to connect and exchange data over the Internet. IoT allows objects to collect and share data autonomously, improving efficiency and enabling smarter decision-making.

Sensors in IoT:

Sensors play a critical role in IoT, as they collect real-time data about the environment or the device itself. These sensors convert physical information into digital signals that can be transmitted over the network.

1. Types of Sensors:

   • Temperature Sensors: Measure temperature variations (e.g., thermocouples).
   • Pressure Sensors: Detect pressure changes (e.g., barometers).
   • Motion Sensors: Detect movement (e.g., passive infrared sensors).
   • Proximity Sensors: Sense the presence or absence of objects (e.g., capacitive, ultrasonic sensors).
   • Light Sensors: Measure light intensity (e.g., photoresistors).
   • Gas Sensors: Detect gases like CO2, methane, etc.
   • Humidity Sensors: Measure moisture in the air.
   • GPS Sensors: Provide geographical location data.

2. Features of IoT:

   • Connectivity: IoT devices need to be connected to networks (Wi-Fi, Bluetooth, ZigBee, 5G) to exchange data.
   • Automation and Control: IoT allows for automation of tasks, such as turning off lights when not in use or adjusting temperature settings in a smart home.
   • Data Processing: IoT devices can process data locally (on-device) or send it to a centralized system (cloud computing) for further analysis.
   • Real-time Monitoring: IoT devices provide continuous real-time data collection and monitoring, making systems smarter and more responsive.
   • Scalability: IoT networks can scale easily by adding new devices or sensors without major infrastructure changes.

Smart Cities:

A Smart City uses IoT technology to enhance urban living, reduce costs, and improve efficiency. The IoT applications in smart cities include:

1. Smart Traffic Management: IoT-enabled traffic lights and sensors monitor traffic flow and adjust light timings in real-time to reduce congestion.

2. Smart Waste Management: IoT sensors in waste bins alert authorities when they are full, ensuring timely collection and optimizing waste collection routes.

3. Smart Water Systems: IoT devices monitor water usage and leakages, ensuring efficient water management and conservation.

4. Energy Management: IoT sensors optimize energy usage in buildings, public spaces, and street lights, reducing overall consumption.

5. Public Safety: IoT-based surveillance cameras and emergency response systems provide real-time monitoring to improve public safety.

6. Healthcare: IoT devices in hospitals can monitor patient vitals and send alerts to healthcare providers, improving care and reducing emergency response times.

Industrial Internet of Things (IIoT):

The Industrial Internet of Things (IIoT) refers to the application of IoT in industries like manufacturing, energy, transportation, and agriculture. IIoT connects machines, sensors, and systems to streamline operations, improve safety, and enable predictive maintenance.

1. Predictive Maintenance: IIoT sensors monitor the health of machines and predict when they are likely to fail, allowing for preemptive repairs and reducing downtime.

2. Supply Chain Optimization: IIoT tracks goods and materials across the supply chain, improving inventory management, logistics, and reducing waste.

3. Automation and Control: IIoT enables automated control of machines, such as adjusting production lines based on real-time data or optimizing energy consumption.

4. Remote Monitoring: IIoT enables operators to remotely monitor industrial machinery, reducing the need for on-site inspections and improving safety.

5. Smart Manufacturing: IIoT connects different stages of production, enabling flexible manufacturing processes, real-time quality checks, and optimized resource utilization.

IoT Challenges:

• Security: IoT devices can be vulnerable to cyberattacks, as they often have limited computing resources to implement strong security measures.
• Interoperability: Different IoT devices and platforms may not always work together seamlessly, creating challenges in integrating various systems.
• Data Privacy: With the vast amount of data generated by IoT devices, privacy concerns around data collection and usage arise.
• Scalability: As IoT networks grow, managing the vast number of devices and the data they generate can become complex.