The OSI model breaks networking into seven distinct layers, each responsible for a specific function.
| Layer | Name | Purpose | Example Technologies |
|---|---|---|---|
| 7 | Application | Interfaces with end-user applications (HTTP, FTP, email) | HTTP, HTTPS, FTP, SMTP |
| 6 | Presentation | Converts data formats, encryption/decryption | SSL/TLS, ASCII, JPEG |
| 5 | Session | Manages connections between applications | NetBIOS, RPC, SIP |
| 4 | Transport | Handles end-to-end communication and reliability | TCP, UDP |
| 3 | Network | Routes packets between different networks | IP, ICMP, BGP, OSPF |
| 2 | Data Link | Transfers frames within the same physical network | Ethernet, Wi-Fi, ARP |
| 1 | Physical | Deals with hardware, cables, and signals | Fiber optics, coaxial cables |
| Session (L5) is layer responsible for starting, maintaining and ending communication between devices. Like when you login to a remote server via SSH. | |||
| Examples include RDP, SSH, Websockets, streaming services, VoIP. |