Let’s start with a simple example.
Host A wants to transmit data through a network to the Host B.
Data from the Session Layer passes to the Transport Layer. There, a header
will be put in front of the data that will provide reliable or unreliable
delivery and perform error correction before retransmit. The data is now named Segment. Then the segment will go
to the Network Layer where a new header will be added that contains information
about the routing that will be needed in order the packet to reach the destination.
The segment is now named Packet/Datagram.
The next layer is the Data Link. The Data Link Layer encapsulates each packet
in a Frame, and the frame’s
header caries the hardware address of the source and the destination hosts. The
finally step is to put the frame on the network. Before this it must first be
put into a digital signal. Physical Layer is responsible for encoding these
digits into a digital signal. The frame now is called bits.
All this process is named Data Encapsulation.
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