The Open Systems Interconnection (OSI) model is a reference model created by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." 🔗
The OSI model is considered by some to be antiquated, but can be still used as a troubleshooting framework to start off with. It generally applies to basic networking, but no longer fits the modern networks. An explaination of this can be found at networkworld.com: Why it's time to let the OSI model die. Also, if you enjoy reading RFC's, you can find The Internet Model from the Internet Engineering Task Force.
| Type | Layer | Name | Function | Example |
|---|---|---|---|---|
| Upper Level | 7 | Application | High-level APIs, including resource sharing, remote file access | HTTP, SMTP, FTP |
| 6 | Presentation | Translation of data between a networking service and an application | SSL, TLS, JPEG, MPEG | |
| 5 | Session | Establishment, maintenance and termination of connections | NetBIOS, PPTP | |
| Transport Level | 4 | Transport | Segmentation and reassembly of data | TCP, UDP |
| 3 | Network | Routing of data | IP, ICMP | |
| 2 | Data Link | Physical addressing | MAC, ARP | |
| 1 | Physical | Media, signal and binary transmission | Ethernet, Wi-Fi |