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Chapter 3
Internet Protocols
The
Host-to-Host layer
parallels the functions of the OSI's Transport
layer, defining protocols for setting up the level of transmission service for
applications. It tackles issues like creating reliable end-to-end communica-
tion and ensuring the error-free delivery of data. It handles packet sequenc-
ing 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 the addressing of hosts by giving them an IP (Internet
Protocol) address, and it handles the routing of packets among multiple
networks. It also controls the communication flow between two hosts.
At the bottom of the DoD model, the
Network Access layer
monitors 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 over-
sees hardware addressing and defines protocols for the physical transmission
of data.
While the DoD and OSI models are alike in design and concept and have
similar functions in similar places,
how
those functions occur is different.
Figure 3.2 shows the TCP/IP protocol suite and how its protocols relate to
the DoD model layers.
F I G U R E 3 . 2
The TCP/IP protocol suite
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