De-encapsulation, the opposite of encapsulation, is
the process of passing information up the stack.
When a layer receives a PDU from the layer below,
it does the following:
1. It reads the control information provided by
the peer source device.
2. The layer strips the control information
(header) from the frame.
3. It processes the data (usually passing it up the
stack).
Each subsequent layer performs this same deencapsulation
process. To continue the preceding
example, when the plane arrives, the box of mail is
removed from the plane. The mailbags are taken
out of the boxes and are sent to the correct post
office. The letters are removed from the mailbags
and are delivered to the correct address. The
intended recipient opens the envelope and reads
the letter.