9. TCP: reliable transport service

TCP (Transport Control Protocol ) is a reliable transport service; to achieve this functionality, TCP defines a number of characteristics:

• byte stream: exchanged data is seen as a stream of bits, divided into bytes, and bytes are received in the order in which they were sent;

• virtual circuit in connected mode: data transfer can only begin once a connection has been established between the two machines. During the transfer, both machines continue to check that the data is being transmitted correctly. The term virtual circuit is used because both application programs see the connection as a physical circuit, the reliability of the transmission being an illusion created by the transport service;

• packet transfer: application programs send their data over the virtual circuit, passing...