Evolution of Computer Networks

Evolution of Computer Networks

Early Communication Systems

• Telegraph (1830s-1840s):
  • First electrical communication system utilizing Morse code.
  • Enabled long-distance text messaging over wires.
• Telephone (1876):
  • Invented by Alexander Graham Bell.
  • Transmitted sound as electrical signals for voice communication.

ARPANET and the Birth of the Internet (1960s)

• Development:
  • ARPANET, funded by the U.S. Department of Defense, marked the beginning of networked communications.
• Packet Switching:
  • Introduced a method where data is split into packets, allowing independent transmission.
• First Message (1969):
  • The initial transmission attempted to send "LOGIN" but crashed after "LO."
  • Full successful transmission was completed later, laying the groundwork for future Internet communications.

Modern Internet (1990s-Present)

• TCP/IP Protocol Suite (1983):
  • Became the standard for ARPANET, consisting of TCP (Transmission Control Protocol) and IP (Internet Protocol).
• World Wide Web (1989):
  • Developed by Tim Berners-Lee, it allowed interlinked hypertext documents accessible via the Internet.
• Expansion and Growth:
  • 1990s saw rapid Internet expansion with web browsers like Mosaic and Netscape.
  • The current Internet connects billions of devices, including computers, smartphones, and IoT devices.

Goals of Computer Networks

Communication

• Email:
  • Early application for instant text communication involving attachments.
• Instant Messaging:
  • Enables real-time text conversations through platforms like WhatsApp and Slack.
• Voice and Video Calls:
  • Supported by technologies like VoIP, facilitating services such as Skype and Zoom.

Resource Sharing

• File Sharing:
  • Utilizes protocols like FTP and peer-to-peer networks for transferring files.
• Printer and Peripheral Sharing:
  • Multiple users can access shared hardware resources, leading to cost savings.
• Application Sharing:
  • Users can access software applications hosted on central servers.

Data Access

• Remote Databases:
  • Allows management and access to data from remote locations.
• Cloud Computing:
  • Provides on-demand access to computing resources and applications via platforms like AWS and Google Cloud.

Entertainment

• Streaming Services:
  • Delivers video and audio content through platforms like Netflix, YouTube, and Spotify.
• Online Gaming:
  • Supports real-time multiplayer gaming experiences via networks (e.g., Steam, Xbox Live).
• Social Media:
  • Facilitates content sharing and interaction among users on platforms like Facebook and Twitter.

Protocol Layering

Concept of Protocol Layering

• Definition:
  • Segregates network communication into layers, each fulfilling specific functions.
• Benefits:
  • Simplification: Makes network management and understanding easier.
  • Interoperability: Allows devices from different manufacturers to work together effectively.
  • Modularity: Enables independent development and updating of separate layers.

OSI Model

• Layers:
  • Physical Layer: Handles raw bitstream transmission through physical media.
  • Data Link Layer: Focuses on error detection, correction, and framing of data.
  • Network Layer: Responsible for routing and addressing of packets (e.g., IP addresses).
  • Transport Layer: Ensures reliable data transfer, utilizing protocols like TCP or UDP.
  • Session Layer: Manages sessions and dialogues between applications.
  • Presentation Layer: Prepares and translates data for the application layer.