2.1 Open System Interconnection Reference Model
ISO(International Standards Organization)OSI(Open System Interconnection) Model
Arranged from high to low, with a total of 7 layers.
- Application: an operating system or network application.ProgramProvides interfaces.
- Presentation layer (Presentation): converts the transmitted content to a meaningful encoding for the user.
- Session Layer: creates, manages, and terminates a session.
- Transport: segments upper-layer data to provide end-to-end transmission and QoS ).
- Network: manage network addresses, select routes, and define data packets ).
- Data Link: Prepare the physical layer, correct transmission errors, and encapsulate data into frames ).
- Physical Layer (physical): Computer + network medium. convert data encoding into bit stream transmission.
2.2 TCP/IP protocol Overview
2.2.1
The TCP/IP model consists of four layers.
