The Department of Defense (DoD) model is basically a condensed version of the OSI model, It includes four rather than seven, layers:
- Process / application layer
- Host-to-host layer
- Internet layer
- Network access layer
Figure 1.5 shows the comparison of Defense and the OSI reference model model. As you can see, These two similar concepts, but each has a different number of layers with different names.
A variety of protocol at the U.S. Department of Defense combined model process / application layer integration Grate the various activities and responsibilities covered by OSI’s corresponding top three focus Layer (applications, demos and meetings). We will pay close attention to these protocol In the next part of this chapter. Process / application layer protocol definition of node-to-node Communications and applications also control the user interface specifications.
The host-to-host layer parallel functions, OSI’s transport layer to determine the protocols established by the application of transmission services. It solves the problem, such as set up end-to-end reliable communications, and to ensure error-free data. It Deal with packet sequence, and maintain data integrity.
Internet layer corresponds to the OSI network layer protocol specified related Law logic packet transmission across the network. It take care of address Mainframe technology, give them an IP address (Internet Protocol), which deal with the routing Between multiple network packets.
At the bottom of the Defense Department model, the network access layer to monitor the data exchange Between hosts and networks. Equivalent to the data link and physical layer OSI model, the network access layer of the hardware deal with the supervision and to identify protocol Physical transmission of data.
The United States Department of Defense and the OSI model at the design and concept and with similar features, Similar layer. Figure 1.6 shows the TCP / IP protocol suite and its protocols and how to relate to Department of Defense model layer.
In the following sections, we will look at the different protocols in more detail, starting with the Process/Application layer protocols.
