Introduction to Computer Networks

Jul 15, 2024

Introduction to Computer Networks

Key Concepts

  • Computer Network: A collection of various computing devices to share data.
  • Purpose: To enable devices to share information, primarily data.

Basic Components

  • Sender and Receiver: Core entities in a network, which can be machines or users sending data via machines.
  • Connection Types:
    • Wired connection
    • Wireless connection

Data Transmission

  • Message Transmission:
    • Sender sends a message (e.g., message "M") to the receiver.
    • Receiver must be able to understand the message.
  • Protocols: Set of instructions running on both sender and receiver machines to ensure data is interpreted correctly.
    • Example: Analogous to needing a common language to understand a verbal message.

Communication

  • Proper Communication: Requires both a connection and protocol.
  • Client-Server Model: Common in network communication where the client and server can be on different machines.
  • Smooth Connection: Essential for seamless data transmission over long or short distances.
  • Abstraction: Users feel seamless interaction due to the network masking the physical separation.

Functionalities in Communication

  • Mandatory Functionalities:
    • Error Control: Ensures the integrity of the message received.
    • Flow Control: Manages the amount of data sent and prevents network congestion.
    • Multiplexing-Demultiplexing: Manages multiple processes sending and receiving data.
  • Optional Functionalities:
    • Encryption-Decryption (Cryptography): Secures data from unauthorized access, crucial for applications like banking.
    • Checkpoint: Useful in data downloading, allowing resumption from the last checkpoint if interrupted.

OSI Model

  • Open System Interconnect (OSI) Model: Standardized model for following protocols in data transmission.
  • Layers of OSI Model: 7 layers dividing network functionalities.
    1. Physical Layer
    2. Data Link Layer
    3. Network Layer
    4. Transport Layer
    5. Session Layer
    6. Presentation Layer
    7. Application Layer
  • Purpose: Ensures data passes through all layers for standard compliance.
  • Alternative Models: TCP/IP model, IEEE model (not detailed in lecture).

Conclusion

  • OSI model divides essential network functionalities into standardized layers, ensuring reliable data transmission between machines.
  • Future discussions will delve deeper into each OSI layer's specific functionalities.
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