TCP / IP Layers & Protocols

Packet Switching Recap

  • Large messages divided into small, numbered packets.

  • Packets routed independently; reassembled at destination using sequence numbers.

TCP/IP Stack Overview

  • Communication is based on a four-layer TCP/IP model.

  • Layers (bottom to top): Network (Link), Internet, Transport, Application.

  • Each layer performs a specific task and interacts with adjacent layers.

Layer Responsibilities

  • Network (Link)

    • Manages physical transmission (signals, MAC addresses).

  • Internet

    • Handles logical addressing (IP addresses) and routing.

  • Transport

    • Manages end-to-end connection and data reliability (segmentation, sequencing, port info).

  • Application

    • Provides services for user programs (e.g., web, email) and prepares data.

Core Protocols by Layer

  • Application: HTTP / HTTPS, FTP, SMTP, IMAP, POP.

  • Transport: TCP, UDP.

  • Internet: IP (IPv4 / IPv6).

  • Network (Link): Ethernet family, Wi-Fi family.

Data Encapsulation Flow

  1. Application layer formats data.

  2. Transport layer adds segments, sequence, and port info.

  3. Internet layer adds IP headers.

  4. Network layer adds MAC addresses and transmits.

  5. Recipient decapsulates data layer by layer.

Advantages of Layered Architecture

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