OSI & TCP/IP Models
The OSI (Open Systems Interconnection) model is a theoretical seven-layer framework for understanding network communication, while the TCP/IP (Transmission Control Protocol/Internet Protocol) model is a practical four-layer model that underpins real-world internet communication.
| Function | OSI | TCP/IP | Protocols | |||
|---|---|---|---|---|---|---|
| Data Generation | Host Layers | Application | 7 | Application | Software | HTTP, SMTP, POP, FTP, SSH, Telnet... |
| Encryption & formatting | Presentation | 6 | TLS, SSL, AFP, ICA, LPP, NCP, NDR... | |||
| Establish connection | Session | 5 | NetBIOS, SMB, NCP, F2F, RPC, SDP... | |||
| Delivery and Sequencing | Transport | 4 | Transport | Network | TCP, UDP, DCCP, SCTP, RSVP... | |
| Routing to Destination | Media Layers | Network | 3 | Internet | IP, NAT, ARP, BOOTP, ICMP... | |
| Local Network Host Delivery | Data Link | 2 | Interface | PPP, HDLC, DSL, ISDN, FDDI... | ||
| Access to Media | Physical | 1 | Ethernet, Wi-Fi, Modems... |
- Does it link? (Layer 1)
- Can you ping it? (Layer 3)
- Does it work? (Layer 7)
OSI Model Mnemonics: Public Discourse Nonsense That Suave Pranksters Appreciate