Mnemonic (Top to Bottom)
All People Seem To Need Data Processing
Mnemonic (Bottom to Top)
Please Do Not Throw Sausage Pizza Away
7
Application
PDU: DataProvides network services directly to end-user applications. Handles high-level protocols, representation, and user interface.
Protocols
Devices
Examples
Troubleshooting
Data Encapsulation
Application Data
TCP/UDP Header Segment
IP Header Packet
Frame Header Frame FCS
Bits: 10110110101001...
Quick Reference
| Layer | Name | PDU | Key Protocols | Devices |
|---|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, FTP, SMTP | Firewalls (L7), Load Balancers |
| 6 | Presentation | Data | SSL/TLS, JPEG, GIF, PNG | Gateways |
| 5 | Session | Data | NetBIOS, RPC, PPTP, SAP | Gateways |
| 4 | Transport | Segment / Datagram | TCP, UDP, SCTP, DCCP | Firewalls (L4), Load Balancers |
| 3 | Network | Packet | IP (IPv4/IPv6), ICMP, OSPF, BGP | Routers, L3 Switches |
| 2 | Data Link | Frame | Ethernet, Wi-Fi (802.11), PPP, HDLC | Switches, Bridges |
| 1 | Physical | Bits | Ethernet (physical), USB, Bluetooth, DSL | Hubs, Repeaters |