TCP/IP Model Cheatsheet

The TCP/IP model is a concise, four-layer framework used to understand and implement network communication.

1. Application Layer

  • Purpose: Interfaces between the network and user applications.
  • Functions:
    • Provides network services to user applications.
    • Handles high-level protocols.
  • Protocols:
    • HTTP, HTTPS (Web Browsing)
    • SMTP, IMAP, POP3 (Email)
    • FTP, SFTP, TFTP (File Transfers)
    • SNMP (Network Management)
    • DNS (Domain Name Resolution)
    • Telnet, SSH (Remote Access)

2. Transport Layer

  • Purpose: Ensures reliable communication between devices.
  • Functions:
    • End-to-end communication.
    • Flow control and error handling.
    • Multiplexing and session management.
  • Protocols:
    • TCP (Transmission Control Protocol): Reliable, connection-oriented.
    • UDP (User Datagram Protocol): Fast, connectionless.

3. Internet Layer

  • Purpose: Handles logical addressing and routing.
  • Functions:
    • IP addressing.
    • Routing and forwarding of packets.
    • Packet fragmentation and reassembly.
  • Protocols:
    • IPv4, IPv6 (Addressing and Routing)
    • ICMP (Error Reporting and Diagnostics)
    • ARP (Address Resolution Protocol)
    • IGMP (Multicast Management)

4. Network Access Layer

  • Purpose: Interfaces with physical network hardware.
  • Functions:
    • Encapsulation of IP packets into frames.
    • Physical addressing (MAC).
    • Access to physical transmission medium.
  • Technologies/Protocols:
    • Ethernet, Wi-Fi (LAN Technologies)
    • PPP (Point-to-Point Protocol)
    • Frame Relay, ATM (WAN Technologies)
    • MAC Addressing

TCP/IP Model vs OSI Model Comparison

TCP/IP LayerCorresponding OSI Layers
ApplicationApplication, Presentation, Session
TransportTransport
InternetNetwork
Network AccessData Link, Physical

Key Characteristics

  • Layer Independence: Each layer operates independently while passing data to/from adjacent layers.
  • Protocol Suite: Flexible and adaptable for various applications.
  • Connection Types:
    • TCP: Ensures reliability through acknowledgments and retransmissions.
    • UDP: Optimized for speed, no error recovery.

Visualization

[ User Data/Application ]
↕
[ Transport Layer (TCP/UDP) ]
↕
[ Internet Layer (IP/ICMP/ARP) ]
↕
[ Network Access Layer (Ethernet/Wi-Fi) ]