Although buffering handles the disp

Although buffering handles the disparity between the speed of the producing and consuming processes, we need one more step before we can send data. The IP layer, as a
service provider for TCP, needs to send data in packets, not as a stream of bytes. At the
transport layer, TCP groups a number of bytes together into a packet called a segment.
TCP adds a header to each segment (for control purposes) and delivers the segment to
the IP layer for transmission. The segments are encapsulated in an IP datagram and
transmitted. This entire operation is transparent to the receiving process. Later we will
see that segments may be received out of order, lost, or corrupted and resent. All of these
are handled by the TCP sender with the receiving application process unaware of TCP’s
activities