Join Telegram Study Group ▷
The Term encapsulation is used to describe the process of adding a header and a tail around some data. The four-tier TCP / IP model can be used to explain this process, and each step describes the role of the layer. For example, when you use your favorite e-mail program, such as Outlook or Thunderbird, to send an e-mail message, the following occurs:
the email is sent from the Application layer to the Transport layer.
The Transport layer encapsulates the data and adds its own header with its own information, such as which port will be used and passes the data to the Internet layer
the Internet layer encapsulates the received data and adds its own header, usually with information about the source and destination IP addresses. The Internet layer than passes the data to the Network Access layer
The network access layer is the only layer that adds both the header and the end of the header. The data is then sent over a physical network link.
Here is a graphical representation of how each layer adds its own information:
encapsulation
Each packet (header + encapsulated data) defined by a particular layer has a specific name:
Frame – encapsulated data defined by the network access layer. A frame can have both a title and a tail.
Packet – Encapsulated data defined by the network layer. The header contains the source IP address and the destination IP address.
The segment is encapsulated data defined by the transport layer. The header contains information such as a source port and a destination port or sequence number and an acknowledgment number.
NOTE
The term "unencapsulation" refers to the process of removing the header and tail as the data is passed from the lower level to the higher level. This process occurs on the computer on which the data is being received.
Data encapsulation in the OSI model
Like the TCP / IP layer, each OSI layer requests services from the next lower layer. The lower layer encapsulates the higher data between the header (the data link protocol also adds a tail).
Although the TCP/ IP model uses terms such as segments, data packets, and frames to reference data packets defined by a particular layer, the OSI model uses different terms: protocol data units (PDUs). The PDU represents a data unit having a header and a header for a particular layer and data of the package. Since the OSI model has seven layers, the number of the PDUs is from 1 to 7 and the physical layer is the first. For example, the term "Layer 3 PDU" refers to data encapsulated at the network layer of the OSI model.
Here is a graphical representation of all the PDUs in the OSI model:
Note: if you are interested in the technology Encapsulation, and you can follow SPOTO.
More you may be interested:
1. New Cisco Certifications Are Coming: 5 Big Changes to Expect
2. Switching Base -VLAN TRUNK VTP
4. A Major Point of CCIE Lab Exam: NAT - Network Address Translation
