 |
Figure 16.1 |
The historic ISO 7-Layer Reference Model. A layering model is a tool
to help protocol designers construct a suite of protocols that solves
all communication problems.
|
|
|
Figure 16.2 |
The conceptual path of data as it travels from an application on
computer 1 across a network to an application on computer 2.
|
|
|
Figure 16.3 |
Examples of older protocol stacks that have been replaced by
TCP/IP protocols. Although the stacks shared many general concepts, the
details differed, making them incompatible.
|
|
|
Figure 16.4 |
The nested protocol headers that appear in a frame as the
frame travels across a network if the full ISO stack is used. Each
layer of protocol software adds a header to an outgoing frame.
|
|
|
Figure 16.5 |
The layering principle applied at each layer of the old ISO model.
If protocol software on the sending computer changes the message, the
change must be reversed by the corresponding protocol software on the
receiver.
|
|
|
Figure 17.4 |
The five layers of the TCP/IP reference model.
|
|
|
Figure 19.8 |
Illustration of the type field in an Ethernet header used to
specify the frame contents. A value of 0x806 informs the receiver
that the frame contains an ARP message.
|
