Assignment
Read
"The
Design Philosophy of the DARPA Internet Protocols" by Dave
Clark. The original paper was published in 1988; the copy of the
paper that we're using was published in 2013, and includes in-line commentary from Dave Clark.
Because networking is a new topic for many of you, we've put
together a
short guide to the
very basics of networking. It should help de-mystify some of the
vocabulary in the DARPA paper. Lecture 8 will also give you a nice
overview, but you need not wait for that lecture before reading this
paper.
We also
recommend this
guide (a bit longer, but still short), which goes into more
detail than ours. It's from 2002, but the concepts still apply
today.
If you are confused by any part of the DARPA paper, especially
terminology, those two guides should be your first resources.
A bit of background on the paper itself:
- This paper was written in 1988, before the Internet was
commercialized. (Prior to commercialization, the NSF controlled most of the Internet
the primary routes that make up the Internet. In the
early nineties, they sold their assets, which allowed private
corporations to gain control. As a result—of this, and of a few
other things—it became easier to do business on the Internet.)
- The paper makes occasional reference to "TCP". We will learn the
details of TCP in a future lecture. For now, you only need to know
that TCP provides reliable transport
(see the networking guide).
The paper starts by introducing the goals of the Internet's
architecture (Sections 1-3). It then dives into the details of some
of these goals (Sections 4-7) before discussing implementation
details and concluding.
As you read, you should think about:
- Why did the Internet architects decide to divide TCP and IP into
two separate protocols?
- How do datagrams help the Internet achieve two
of its goals: to connect existing networks and to survive
transient failures?
- If you could start from scratch, how would you redesign the
Internet today? Would you keep the same principles but change their
order? Would you use new principles?
Question for Recitation
Before you come to this recitation, write up (on paper)
a brief answer to the following (really—we don't need
more than a couple sentences for each question). If your TA has
requested that you email your answer to them, you may do that instead,
but it should still be handed in before your recitation begins.
Your answers to these questions should be in your own
words, not direct quotations from the paper.
- What were three of the most important goals of the early Internet?
- How was it designed to meet those goals?
- Why were those goals important (or, why does the author believe
that those goals were important)?
As always, there are multiple correct answers for each of these
questions.
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