CCNA®: Cisco® Certified Network Associate: Fast Pass, Third Edition

1.3. Use the OSI and TCP/IP models and their associated protocols to explain how data flows in a network

The Department of Defense (DoD) model is basically a condensed version of the OSI model—it's composed of four, instead of seven, layers:

• Process/Application layer

• Host-to-Host layer

• Internet layer

• Network Access layer

Figure 1.5 shows a comparison of the DoD model and the OSI reference model. As you can see, the two are similar in concept, but each has a different number of layers with different names.

Figure 1.5. The DoD and OSI models

NOTE

When the different protocols in the IP stack are discussed, the layers of the OSI and DoD models are ...