The first layers: the physical
Physically defined by a network device for transmitting data; as an interface between the network media and equipment; defined optical, electrical and mechanical characteristics
Second layer: data link layer
Program defines a communication connection; encapsulated packet data frame; detecting and correcting errors packet transmission
The third layer: The network layer
How to transfer data between network devices is defined; according to the unique device address of the network to route packets; providing a flow and congestion control to prevent loss of network resources
Fourth layer: the transport layer
Management information transmission network end opening; providing a reliable and orderly packet transfer through error correction and flow control mechanisms; transport packet provides connectionless
The fifth layer: Session Layer
Manage user sessions and dialogue; to establish control and hang up the logical connection between the user; a layer error occurred on the report.
Sixth Layer: The presentation layer
Masking the different data formats of different systems; designated data transmission format independent mechanism; data encoding and decoding; encryption and decryption; compression and decompression.
Seventh layer: Application Layer
It defines an interface for network communication and data transmission - the user program; standard services, such as transmission and processing of the virtual terminal, and the task file.