Global Protocol Classifications
41
As you can see, both systems do a lot of communicating, aside from the
exchange of data. From the connection request to the termination acknowl-
edgment, every exchange is accompanied with control information that
keeps the data transfer reliable and error-free. Table 2.1 gives examples of
several connection-oriented protocols.
Connectionless Protocols
Now that connection-oriented protocols have been discussed, we'll move on
to connectionless protocols.
Connectionless protocols
differ from connec-
tion-oriented protocols because they do not provide for flow control.
Figure 2.7 shows you how connectionless protocols work. This figure
looks somewhat like Figure 2.3, except that there are no steps that involve a
connection setup or termination. It is also missing the flow and error control
information sent by the receiving system.
T A B L E 2 . 1
Connection-Oriented Protocols
Protocol Name
Protocol Description
ATM
ATM (Asynchronous Transfer Mode) uses virtual
circuits from one node to another. The permanent
virtual circuits, or PVCs, are established by using
connection-oriented procedures.
TCP
TCP (Transmission Control Protocol) was devel-
oped to overcome reliability problems. It uses flow
and error control extensively.
Novell SPX
Novell SPX (Sequenced Packet Exchange) is Nov-
ell's implementation of a network protocol that pro-
vides error-free and reliable data transport.
AppleTalk ATP
Apple uses ATP (AppleTalk Transaction Protocol)
to provide connectivity between two socket clients.
It is based on the request/response interaction of
the two clients.
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