What makes WiFi faster at home than at a coffee shop? How does Google order its search results from the trillions of webpages on the Internet? Why does Verizon charge $15 for every GB of data we use? Is it really true that we are connected in six social steps or less? These are just a few of the many intriguing questions we can ask about the social and technical networks that form integral parts of our daily lives. This course is about exploring the answers, using a language that anyone can understand. We will focus on fundamental principles like “sharing is hard”, “crowds are wise”, and “network of networks” that have guided the design and sustainability of today’s networks, and summarize the theories behind everything from the social connections we make on platforms like Facebook to the technology upon which these websites run. Unlike other networking courses, the mathematics included here are no more complicated than adding and multiplying numbers. While mathematical details are necessary to fully specify the algorithms and systems we investigate, they are not required to understand the main ideas. We use illustrations, analogies, and anecdotes about networks as pedagogical tools in lieu of detailed equations. All the features of this course are available for free. It does not offer a certificate upon completion.
Networking Principles Without "Calculus"
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En provenance du cours de Princeton University
Networks Illustrated: Principles without Calculus
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Introduction
An introduction to what this course is about: the fundamentals behind social and technical networks.
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Christopher BrintonLecturer
Electrical Engineering
Mung ChiangProfessor
Electrical Engineering
Hello and thanks for waiting. Welcome to our course titled Networks
Illustrated, Principles without Calculus. My name is Chris Brinton.
I'm a third year PHD candidate at Princeton University and I'll be teaching
this course along with my adviser, Professor Mung Chiang of Electrical
Engineering at Princeton University. In this lecture I want to give an
overview of what we will be learning in this course and how we will go about
learning. So the first thing that probably comes to
your mind is What is a network? Well, if you look that in the dictionary,
you come up with some pretty complicated definition.
For instance, an openware fabric or structure in which cords, threads or
wires cross at regular intervals. So, we would have some wires [SOUND]
maybe that are crossing [SOUND] at some regular intervals.
Or another one, a group of interconnected via cable and/or wireless, computers and
peripherals that is capable of sharing software and hardware resources between
many users. So there are many complicated terms
there, we heard, you know, users Like you or me, that are connected over maybe
wireless, or long cables. So those two definitions are pretty
complicated, and they probably leave you with a big question mark.
So now let;s discuss something simpler. What about a group of people like you and
me or things like smartphones, laptops, desktops, or tablets that are all
connected in some way. Now those connections might be over
wireless or cables or they might be overt the air over a wireless interface or they
could be social connections, for instance on Facebook.
Facebook if you and I are connected and become friends.
[SOUND] So, hopefully this makes a little more sense.
[SOUND] You may have a nice light bulb on your head right now.
So, these definitions on the left-hand side will become clearer to you as we go
throughout this course but we'll stick to this definition for now.
Now, where are these networks? Well, simply put, they're everywhere.
We have social networks like Facebook, Twitter or YouTube.
Now Facebook we have networks of friends, friend relationships.
On Twitter we have networks of following relationships, who you're following, who
is following you. Now, on YouTube, we have networks of
people who are talking, or we have networks of movies, videos.
We also have technological networks like cellular or 3G, maybe 4G that you might
use on your smartphone. We have WiFi, for instance, on your
smartphone or on your laptop device. And we also have the internet, which is
basically where all of these tasks run on top of.
So, you see Here we have a wide variety of of technological networks, starting
off with 3G, Wi-Fi or the Internet just being three examples.
And we also have economic networks, which is basically how we're priced for all the
services that we use and we have to pay for the Internet.
And that determines how we pay and how much we have to pay.
So if you think about it, our lives would be a lot different if we didn't have all
of these networks. So what do you need to know for this
course? You probably saw a similar course, which
is called, Networks, Friends, Money, and Bytes, that we have had on course to us
already. In that one we had a prerequisite of
calculus and linear algebra, where we're dealing with a lot of matrices.
So we may have written some complicated equation that looked something like this.
Pi of T, sequence of gamma I over SIR i of t times pi of t minus 1.
So we have a lot of symbols, for instance this p here.
We have a lot of subscripts, for instance that i, and things like sir and t for
time, which make it mathematically convenient to write down, but it doesn't
help the fact that it's pretty confusing. So in this course, we thought a lot about
how to present the material. And now we have two different
prerequisites. The first one is chalkboard math if you
will, like addition, multiplication, subtraction and division.
And the second one is just a desire to learn.
So we realized we can take this equation right here and write it in its English
form, a lot simpler. So we have, here, the next power, which
your cellphone will transmit it at is equal to this thing called the ratio
times the current power. So now all we need to do is multiply
these two things and we'll get the next power.
That looks a lot simpler than this equation right here, so we'll be using
chalkboard math rather than calculus and linear algebra [SOUND] and hopefully that
makes a lot more sense. Now how are these lectures presented?
Well we thought about what the best teaching style would be, or, pedagogy, if
you will, is for this type of material. And we summarize that in three As.
The first one, is analogies. Networks lend themselves very well to
analogies, things like transportation networks or the postal system.
For instance, we can relate congestion in the internet to what happens when you sit
in a traffic jam. And we can relate how Pieces of data get
through the internet. So, what happens when you send email to
someone and how it goes to all intermediate post offices along the way.
The second A is anecdotes. So, a lot of times best way to explain
some of these networking concepts is to tell stories and history about how they
came to be in the first place. And the third A is animations.
That's probably the most important. So Indeed, they say that a picture is
worth a thousand words and networks are no exception to that.
So, we'll be using a lot pictures to explain a lot of these tools.
So, now, each of these lectures revolves around a few key principles, namely we
have eight of them, which we call 8P. And these principles are simple phrases
that could probably fit within these two quotation marks right here.
So they're three or four words each, and they summarize a vast amount of network
ideas. And so we'll go through some of these
principles. Specifically we'll go through five out of
the eight of them. And we'll go through some of the topics
involved in them. The reason we're only going to do five is
because we only have six weeks together. So we'll just do as much as we can.
Now the question is, what are these principles.
So let's briefly go through them
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