Answer:
None
Explanation:
The OSI model is one of two network models ( with TCP/IP as the second), it has seven layers and they are mostly ranked from the PDU entry point. PDU is the data format of a layer as encryption information of the layer is added to it.
Starting from the last or seventh layer;
- Application layer: In this layer, data is created and manipulated by a user. At this point, the PDU is just data as it is where creation of data to be sent and receiving of data to manipulated is done.
- Presentation layer: Encryption of the data takes place here and is dependent on the application layer.
- Session layer: the session between the communicating computers occurs here.
-Transport layer: the data to be transferred is for a specific application in the computer, so a transport header which contains a port number to identify the application is given. The PDU of the combined transport header and data is called a "segment".
- Network layer: The segment moves to this layer and a network header containing an IP address and subnet mask is added. This new pdu is called a "packet".
- Data-link layer:Here, a header and trailer is added containing the MAC address and error checking information and this new pdu is called "Frame".
_ physical layer: this layer is responsible for delivering and accepting PDUs from the medium (wired or wireless). The frame is encoded to the PDU called bits and are sent to the other computer through a wired medium.
Summary: PDU
( Application to session) - Data
Transport. - Segment
Network. -. Packet
Data-link. -. Frame
Physical. -. Bit
