| OSI Layers | TCP/IP | X.25 | X.400 | X.500 |
| 7. Applications | SMTP, FTP, TELNET,DNS | Create directory | ||
| 6. Presentation | ||||
| 5. Session | ||||
| 4. Transport | TCP | |||
| 3. Network | IP | Packet Layer Protocol | ||
| 2. Data Link | Protocols defined by underlined network | Link Access Protocol | ||
| 1. Physical | EIA-232 |
