Computer Network Communication and Protocols

Jun 13, 2024

Lecture Notes: Computer Network Communication and Protocols

Introduction to Communication

  • Two people communicating need a common language.
  • Computers need a common message format for communication.
  • A common set of rules (protocols) are required for communication in networks.
  • Protocols ensure proper message formatting and transmission.

TCP/IP Protocol Suite

  • TCP/IP supports network communication.
  • Network: Two computers connected via LAN Cable.
  • Communication: Sending digital messages over a medium (wired/wireless).
  • Messages are broken into smaller data units for transmission.

TCP vs. UDP

  • TCP (Transmission Control Protocol)
    • Breaks messages into segments, reliable but slow.
    • Used for essential, error-free data transmission.
    • Phases: Connection Establishment, Data Transfer, Connection Termination.
    • Three-Way Handshake for connection setup.
  • UDP (User Datagram Protocol)
    • Faster, less reliable.
    • Used for streaming, DNS, DHCP, SNMP, and RIP.

Network Models

  • TCP/IP Model: Practical model, supports different manufacturers.
  • OSI Model: Used primarily for research.
  • Layers of TCP/IP: Application, Transport, Network, Data Link, Physical.

Layers Overview

  • Application Layer: Generates the message.
  • Transport Layer: TCP segments or UDP datagrams.
  • Network Layer: IP packets, logical addressing, routing, path determination.
  • Data Link Layer: Ethernet frames, MAC addressing, error checking.
  • Physical Layer: Actual communication, binary signals over media.

Data Link Layer

  • Divided into MAC and LLC sublayers.
  • MAC Sublayer:
    • Data encapsulation with headers and trailers.
    • CSMA/CD for media access.
  • LLC Sublayer:
    • Flow control to prevent overwhelming the receiver.
    • Error control (ARQ for retransmission).

Network Layer Functions

  • Adds logical (IP) addresses, uses routers for data delivery.
  • Path Determination: Choosing best path using OSPF, BGP, IS-IS.
  • Routing done by routers, ARP for intranet communication.

Transport Layer

  • Ensures error-free, ordered data transfer.
  • TCP:
    • Sequence numbers for ordered transfer.
    • Retransmission of lost data.
    • Connection-oriented with Three-Way Handshake.
  • UDP:
    • Unreliable, no segmentation support, faster.

Application Layer Protocols

  • DNS: Translates IP addresses to domain names.
  • DHCP: Assigns IP addresses automatically.
  • FTP: Transfers files on the internet.
  • HTTP/HTTPS: Web page transmission.
  • IMAP, POP3, SMTP: Email protocols for retrieval and transmission.
  • IRC: Internet chat protocol.

Conclusion

  • TCP/IP protocol suite comprises various protocols at different layers.
  • Key protocols ensure successful digital communication over networks.
  • Understanding these protocols is crucial for network communication.

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