Networking · 03 · 3 min read

The TCP/IP model

The practical four-layer model the internet is built on.

Four layers

4ApplicationHTTP, DNS, SSH — OSI 5–7

3TransportTCP, UDP — OSI 4

2InternetIP, ICMP — OSI 3

1LinkEthernet, Wi-Fi — OSI 1–2

OSI vs TCP/IP

OSI is the detailed textbook map; TCP/IP is the real road system. They describe the same journey — TCP/IP just merges the top three and the bottom two OSI layers.