In a two-way conversation with confirm, the sending side issues
a confirmation request and must wait for confirmation from the receiving side
before transmitting any more information. Figure 2-4 “Two-Way Phone Conversation With Confirm” is
an illustration of a two-way conversation with confirm.
Figure 2-4 Two-Way Phone Conversation With Confirm
Confirmation ensures that the two sides of the conversation
remain synchronized, but it increases the amount of control information
and the number of transmissions necessary to transmit data.