- The Transmission Control Protocol Internet Protocol suite
better known as TCPIP, was designed and implemented
by the US Department of Defense,
to ensure and preserve data integrity
as well as maintain communication
in the event of catastrophic war.
If designed and implemented correctly, a TCPIP network
can be secure, dependable and resilient.
I'll begin by exploring the DOD's version of TCPIP
then I'll compare that version and it's protocols
with the OSI reference model that we discussed earlier.
The DOD Model is basically a condensed version
of the OSI model that's comprised of four
instead of seven layers.
The four layers are Process/Application, Transport,
Internet and Link.
This graphic offers 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.
I'll focus on a few of the most important applications
found in the season objectives.
First, it's worth noting that CISCO sometimes uses multiple
names for the same layer.
The transport layer is also referred to as Host-to-Host,
while Network Access and Link are used to the describe
the Physical and Data Link layers.
A vast array of protocols join forces
in the DoD Process/Application layer.
These processes combine the OSI Model's top three layers.
Application, Presentation and Session.
In short, the Process/Application layer defines
protocols for node-to-node application communication
and controls user interface specifications.
The DoD Transport layer parallels
the functions of the OSI's Transport layer.
Define protocols for setting up the levels
of transmission service for applications.
It tackles issues like creating reliable
end-to-end communication
and ensuring error-free delivery of data.
It handles Packet Sequencing and maintains data integrity.
The internet layer corresponds to the OSI's network layer,
designating the protocols relating
to the logical transmission of packets
over the entire network.
It takes care of host addressing
by giving them an IP address
and handles the routing of packets among multiple networks.
At the bottom of the DoD Model, the Network Access layer
or Link layer implements the data exchange
between the host and the network.
The equivalent of the Data Link
and Physical layers of the OSI Model,
the Network Access layer oversees hardware addressing
and defines protocols for the physical transmission of data.
TCPIP became so popular,
because there are no set Physical layer specifications.
So it can run on any existing or future physical network.