7-tier network architecture

Reference article

Understand the seven-layer network protocol/OSI seven-layer model in one article

7-layer network architecture

1. Physical layer: It mainly defines the physical equipment standards, such as the interface type of the network cable, the interface type of the optical fiber, and so on. Its main function is to transmit bit stream (that is, it is converted from 1, 0 to current strength for transmission, and after reaching the destination, it is converted to 1, 0, which is what we often call analog-to-digital conversion and digital-to-analog conversion).
2. Data link layer: Mainly carry out MAC address (network card address) encapsulation and decapsulation of data received from the physical layer. This layer of data is often called a frame. The equipment working at this layer is a switch, and data is transmitted through the switch.
3. Network layer: mainly encapsulate and decapsulate the IP address (for example, 192.168.0.1) of the data received from the lower layer. The devices working at this layer are routers, and the data at this layer are often called packets.
4. Transport layer: defines some data transmission protocols and port numbers (WWW port 80, etc.), such as: TCP (transmission control protocol, low transmission efficiency, strong reliability, used for high reliability requirements, large data volume data) , UDP (User Datagram Protocol, on the contrary with TCP characteristics, used to transmit data with low reliability requirements and small data volume, such as QQ chat data is transmitted in this way). The main purpose is to segment the data received from the lower layer for transmission, and reorganize it after reaching the destination address. This layer of data is often called a segment.
5. Session layer: The data transmission path is established through the transport layer (port number: transmission port and receiving port). Mainly initiate sessions or accept session requests between your systems (devices need to know each other, which can be IP, MAC, or hostname)
6. Presentation layer: mainly for interpretation, encryption and decryption, compression and decompression, etc. of the received data (that is, converting what the computer can recognize into what an adult can recognize (such as pictures, sounds, etc.))
7. The application layer is mainly for some terminal applications, such as FTP (various file downloads), WEB (IE browsing), QQ and the like (you can understand it as what we can see on the computer screen. It is the terminal application. ).

Finally, I will give you a horizontal comparison of the differences between the TCP/IP 4-layer model, the 5-layer model, and the OSI seven-layer model.

Interactive machine and router function