工程师 - OSI model

OSI model Reference model The Open Systems Interconnection (OSI) model is a reference model from the International Organization for Standardization (ISO) that provides a common basis for the coordination of standards development for the purpose of systems interconnection.
Layers	Seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application
Purpose	Describes networked communication from physical transmission to application data representation
Development	Started in the late 1970s by the International Organization for Standardization (ISO)
Comparison	Less rigorous than the Internet protocol suite but widely accepted for teaching networking
Functionality	Each layer serves a class of functionality to the layer above and is served by the layer below