TCP/IP and the DoD Model
Written on 05:48 by Ahmet Emir
The DoD archetypal is basically a abridged adaptation 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 2.1 shows a allegory of the DoD archetypal and the OSI advertence model. As you can see,
the two are agnate in concept, but anniversary has a altered cardinal of layers with altered names.
FIGURE 2 . 1
The DoD and OSI models
When the altered protocols in the IP assemblage are discussed, the layers of the OSI
and DoD models are interchangeable. In added words, the Internet band and
the Arrangement band call the aforementioned thing, as do the Host-to-Host band and the
Transport layer.
A all-inclusive arrangement of protocols amalgamate at the DoD model’s
Process/Application layer
to integrate
the assorted activities and duties spanning the focus of the OSI’s agnate top three
layers (Application, Presentation, and Session). We’ll be attractive carefully at those protocols in
the abutting allotment of this chapter. The Process/Application band defines protocols for node-to-node
application advice and additionally controls user-interface specifications.
The
Host-to-Host layer
parallels the functions of the OSI’s Transport layer, defining protocols
for ambience up the akin of manual account for applications. It tackles issues such as
creating reliable end-to-end advice and ensuring the error-free commitment of data. It
handles packet sequencing and maintains abstracts integrity.
The
Internet layer
corresponds to the OSI’s Arrangement layer, anecdotic the protocols relating
to the analytic manual of packets over the absolute network. It takes affliction of the acclamation of
hosts by giving them an IP (Internet Protocol) address, and it handles the acquisition of packets
among assorted networks.
At the basal of the DoD model, the
Network Access layer
monitors the abstracts exchange
between the host and the network. The agnate of the Abstracts Link and Concrete layers of the
OSI model, the Arrangement Access band oversees accouterments acclamation and defines protocols for
the concrete manual of data.
Introduction to TCP/IP
The DoD and OSI models are akin in architecture and abstraction and accept agnate functions in
similar layers. Figure 2.2 shows the TCP/IP agreement apartment and how its protocols chronicle to the
DoD archetypal layers.
FIGURE 2 . 2
The TCP/IP agreement suite
In the afterward sections, we will attending at the altered protocols in added detail, starting with
the Process/Application band protocols.
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