Connections:

Connections:

    The reliability and flow control mechanisms described above require    that TCPs initialize and maintain certain status information for    each data stream.  The combination of this information, including    sockets, sequence numbers, and window sizes, is called a connection.    Each connection is uniquely specified by a pair of sockets    identifying its two sides.

    When two processes wish to communicate, their TCP’s must first    establish a connection (initialize the status information on each    side).  When their communication is complete, the connection is    terminated or closed to free the resources for other uses.

    Since connections must be established between unreliable hosts and    over the unreliable internet communication system, a handshake    mechanism with clock-based sequence numbers is used to avoid    erroneous initialization of connections.

  Precedence and Security:

    The users of TCP may indicate the security and precedence of their    communication.  Provision is made for default values to be used when    these features are not needed.