Data encapsulation
Data encapsulation can mean:
- Hidden information that cannot be seen without any call of them
- the wrapping of private data in classes in object-oriented programming languages: see information hiding and separation of concerns
- protocol layering in communications protocol design
When a host transmits data across a network to another device, the
data is encapsulated with protocol information at each layer of the OSI model.
Each layer communicates only with its peer layer on the receiving device.
To communicate and exchange information, each layer uses what are called
Protocol Data Units (PDUs). These hold the control information attached to
the data at each layer of the model, which is typically attached to the header
of the data field but can also be in the trailer, or end of the data field.
Each PDU is attached to the data by encapsulating it at each layer of the
OSI model. Each PDU has a specific name depending on the information
each header has. This PDU information is only read by the peer layer on the
receiving device and then is stripped off and the data is handed to the next
upper layer.
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