ABSTRACT
As previously described in Chapter 2, a datagram is composed of transport layer data (segment), to which an IP header is added. ˆis is the basic concept of encapsulation, where, at the transmitter side, the upper layer data (segment) is transferred to an adjacent lower layer (datagram) and added with overhead (source and destination IP address, sequence numbers, etc.). ˆe opposite operation, called de-encapsulation, is performed at the destination side, where a lower layer removes its layer’s header (e.g., IP header) before the data (IP payload) is transferred to an upper layer (as a segment).
