An interactive reference for the OSI 7-layer model, the Protocol Data Units that travel through it, and the protocols — HTTP, DNS, QUIC, TCP, UDP, and IP — that keep every request and reply moving.
Click any layer to see its job, the data unit it works with, and the real protocols that live there.
Every layer wraps what it receives in its own header (and sometimes a trailer) before handing it down. That wrapping — and unwrapping on the way back up — is called encapsulation and decapsulation.
Filter by OSI layer or by connection profile, then open a card to see its handshake, header fields, and behavior.