OSI Layer-7 Reference Model

 

(1) physical layer: transmits the original data bit stream over the communication channel.

 

(2) data link layer: Let the sender split the input data into data frames and then transmit these data frames in sequence. Then, a traffic adjustment mechanism is provided to let the sender know how much cache the receiver currently has to avoid a fast sender flooding out a slow receiver.

 

(3) network layer: how to determine whether a group is routed from the original end to the target end. The paths at both ends are based on static tables, blocking control, delay, and transmission time, jitter is also at the network layer (the transmission unit is packet grouping ).

 

(4) Transport Layer: Accept data transmitted from the previous layer to the network layer. If necessary, divide the data into small units and pass the data to the network layer to ensure that the data reaches the other end correctly.

 

(5) Session Layer: Allows users on different machines to establish sessions. The so-called session is usually a service that includes session control and Token management synchronization.

 

(6) Presentation Layer: Focus on the syntax and semantics of the transmitted information.

 

(7) Application Layer: including various protocols, which are usually applicable to user requirements, such as HTTP.