Open OSI seven-layer model:
First, the physical layer:
Original bit stream transport mechanism, electronics, timing interface communication channels;
Second, the data link layer:
Physical addressing, while the original bit stream into logical transmission lines;
Third, the network layer:
Control subnets, such as logical addressing, packet transmission, routing;
Fourth, the transport layer:
Receiving layer of the data, when necessary, the data is divided, and the data to the network layer, and ensures that the data arrive at the effective end;
Fifth, the session layer:
The establishment of several management sessions between users on different machines;
Sixth, the presentation layer:
Syntax and semantics and their associated information, such as encryption and decryption, translation conversion, compression and decompression;
Seventh, the application layer:
Message header resolution mode;