Network Layer of OSI Reference Model

 while TCP/IP is the newer model, the Open Systems Interconnection (OSI) model is still referenced a lot to describe network layers. The OSI model was developed by the International Organization for Standardization. There are 7 layers:

Physical (e.g. cable, RJ45)
Data Link (e.g. MAC, switches)
Network (e.g. IP, routers)
Transport (e.g. TCP, UDP, port numbers)
Session (e.g. Syn/Ack)
Presentation (e.g. encryption, ASCII, PNG, MIDI)
Application (e.g. SNMP, HTTP, FTP)
People have come up with tons of mnemonic devices to memorize the OSI network layers. One popular mnemonic, starting with Layer 7, is “All People Seem To Need Data Processing.” But one that I’m partial to, which starts with Layer 1, is “Please Do Not Throw Sausage Pizza Away.”

The TCP/IP model is a more concise framework, with only 4 layers:

Network Access (or Link)
Internet
Transport (or Host-to-Host)
Application (or Process)

Also read : network levels

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