STUDY GUIDE
FOR LEARNING MODULE IV
AN OVERVIEW OF
TCP/IP, PROTOCOLS, and the OSI MODEL
Under construction!
Will be developed throughout the Summer, 1999.
INTRODUCTION
The fourth learning module is a rather ambitious attempt to help the learner
understand the complexities of the TCP/IP suite of protocols. To
say that the Internet is complex is the "mother of all understatements"!
Because it is such a complex interaction
of programs, each implementing subtly different protocols, it is useful
to compare the TCP/IP protocol suite to a theoretical model of communication
protocols, the "OSI model." However,
discussion of this model introduces more complexity.
I think there is a balance somewhere
between not mentioning the OSI model and covering it in detail. That
balance is what I try to reach with this learning model, enough OSI model
to help understand TCP/IP but not so much that would divert attention away
from the focus of this course, the Internet.
COMMENTS:
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It is risky to give analogies, but I'll run
that risk because if one wants to understand the mysteries of the Internet,
it
is critical to understand the idea of protocols. A data communication
protocol is a set of rules, defined on paper, that govern the transmission
of data between two devices; in the case of TCP/IP the devices are on a
network. It is thought provoding to think of the "communications
protocol" that you and I are using to communicate these ideas in this document.
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In class I ask this question and students
typically say that "English is our protocol", and I respond "You are on
the right track, but English really is a language, not a protocol."
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Then I continue, "However, English is our
means of communication, and the communications themselves implement
a protocol; in fact one could say (rather loosely) that these words
you are reading use English and implement the 'protocols of English'".
Then I ask, "From a simple viewpoint, what are
the 'protocols of English communication'?" You should
try
to answer this question, yourself, before reading the next item.
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After some guided discussion, the class agrees
that if there were "protocols of English", they would include the _________
of English words and the __________ which governs how the words are organized
into sentences. I think this is the best analogy that can give you
insight into the prococols governing communications between two network
devices. Remember, however, that the protocols (rules defined
on paper) must be "implemented", either in software or hardware, like
I implement the "protocols of English" in this document.
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