| Ports Data Encapsulation |
| TCP/IP DoD Model Network |
1. TCP/IP History
The TCP/IP model originated in the 1970s and became the official ARPAnet standard in 1983. Developed under IETF guidance, it laid the foundation for today’s Internet.
2. DoD Model vs. OSI Model
- Process/Application: Equivalent to OSI’s Application, Presentation, and Session layers
- Host-to-Host: Corresponds to the OSI Transport layer
- Internet: Maps to OSI’s Network layer
- Network Access: Covers OSI’s Data Link and Physical layers
3. Application Layer Protocols
- FTP (TCP 20,21), SFTP/SSH (TCP 22)
- Telnet (TCP 23), SMTP (TCP 25), DNS (TCP/UDP 53)
- DHCP (UDP 67/68), TFTP (UDP 69), HTTP/HTTPS (TCP 80/443)
- POP3 (TCP 110), IMAP (TCP 143), SNMP (UDP 161/162)
- LDAP (TCP 389), LDAPS (TCP 636)
- MySQL (TCP 3306), RDP (TCP 3389)
- SIP (TCP/UDP 5060/5061), RTP (UDP/TCP 5004/5005)
4. Host-to-Host Layer Protocols
| Feature | TCP | UDP |
|---|
| Sequencing | Yes | No |
| Reliability | Yes | No |
| Connection-Oriented | Yes | No |
| Overhead | High | Low |
| Acknowledgment | Yes | No |
| Flow Control | Yes (Windowing) | No |
5. Port Numbers
| Protocol | Port | Transport Layer |
|---|
| FTP | 20, 21 | TCP |
| DNS | 53 | TCP/UDP |
| HTTP | 80 | TCP |
| HTTPS | 443 | TCP |
| SMTP | 25 | TCP |
| DHCP | 67, 68 | UDP |
| RDP | 3389 | TCP |
6. Internet Layer Protocols
- IP: Logical addressing and routing
- ICMP: Error messaging and network diagnostics
- ARP: Resolves IP to MAC address
- RARP: Resolves MAC to IP address
- GRE: Tunneling various protocols
- IPSec: Secure communication via AH and ESP
7. Data Encapsulation Process
Application Layer → User Data
Transport Layer → Segment (TCP/UDP Headers)
Network Layer → Packet (IP Headers)
Data Link Layer → Frame (MAC + CRC)
Physical Layer → Bits transmitted
8. Conclusion
TCP/IP delivers scalable, secure, and reliable communication. Understanding its layered architecture enables network management, troubleshooting, and design of robust infrastructures across varied platforms.
