Intro to networked devices and IP through NYU-NET

1. A packet's journey through NYU-NET
The Neverending
Story

2. WELCOME TO
NYU-NET
NYU-NET is NYU’s Internet-connected
network of computers, computer-related
equipment, and information resources. It
is a collection of hardware, software,
operating procedures, and policies. It
enables your devices to talk with other
devices in the network and out of the
network on the Internet. It is also how
you can get access to NYU online
resources, such as Albert, where you can
sign up for classes.

3. To understand this better,
let's take a journey as a data
packet and see what it takes
to go from the origin device
to the destination device.
You may ask, why are there so
many things just for my device to
connect to the Internet?
Like the rest of the Internet,
NYU-NET depends on hardware, such
as routers, switches, and cables,
to physically connect the
network, the software that is
used to program these networked
devices, and the policies that
dictate how data is sent between
devices in the network.

4. LET THE
JOURNEY
BEGIN

5. What's a data packet?
A data packet is data packaged
with information about where it
came from and where it's headed.
There are different data packet
types used for different types of
data, such as text data from an
email, streaming video or audio
data, or a request for
information, such as the ones you
make when you try to access a web
page in a browser.
What's a frame?
A frame wraps around the data
packet. It lets network devices
know information about the packet.
Why is the frame useful? We'll see
soon.
A data packet is born... on
a laptop connected to
NYU-NET through
ethernet cable.
My name is HTTPlz.
I’m a data packet
wrapped by a frame.
My mission is to
request for the
www.nyu.edu.

6. SERVER
where
www.nyu.edu is
hosted
LAPTOP
NYU-NET
???
???
??????
???
???
???
???
??????

7. HTTPlz leaves the laptop
and gets to another floor
in the building through
ethernet cable
Started from the
4th floor of the
Tisch building
What is this
on the 12th
floor?

8. THE SWITCH
HTTPlz: Hi, my
name is HTTPlz,
I'm requesting... Switch: I do not
understand. Where
are you from and
where are you
going?

9. SWITCH
HTTPlz: phew...I
have the MAC
addresses here on
my frame.
Switch: The device
you are looking
for is that way.
Pass through this
port.
What does a switch do?
A switch takes frames from all the
devices that are connected to it
and send them on the right way to
the next device. They can tell
where the packet is from by the
MAC address of the origin device,
in our case the laptop.
How about MAC addresses?
A device's MAC address uniquely
identifies it and is given by its
manufacturer. It's like the door
number of a house, if the laptop
is the house.

10. HTTPlz continues through
the cables along with
other packets
I’m on my way to
ping a server
somewhere...
I’m a streaming
video clip...

11. ROUTER
HTTPlz: phew...I have the MAC
addresses here on my frame.
HHTPlz: Here are the MAC addresses. Where should I go?
router: Hello friend, I need more information than that.
You are about to leave the Tisch subnet and get into the
main NYU-NET.
HHTPlz: What?! I thought I was already in NYU-NET?
router: Please step out of your frame.
HHTPlz: What??
router: I need to look inside your frame to know what type
of package you are and the IP address of where you are
from and where you are going.

12. router: I see that you came
from 128.122.151.2 and is
going to 128.122.119.202.
HTTPlz: I feel exposed.
router: Do not be afraid. I
do this all day. I've seen
everything.
What are subnets?
Subnets are smaller networks part
of a larger network. NYU has many
subnets for different schools and
programs. For a data packet to go
outside of the subnet, the device
sending it needs an IP address.
What does IP stands for?
IP stands for Internet Protocol.
Protocols are rules that dictate
how fast data can be sent and how
the data should be structured.
What’s an IP address?
IP address combines a network
address and the host address. Like
the address on a letter, it has the
the state and street address as
well as information of the
recipient of the letter.

13. HTTPlz: phew...I have the MAC
addresses here on my frame.
HHTPlz: Here are the MAC addresses. Where should I go?
router: Hello friend, I need more information than that.
You are about to leave the Tisch subnet and get into the
main NYU-NET.
HHTPlz: What?! I thought I was already in NYU-NET?
router: Please step out of your frame.
HHTPlz: Why?
router: I need to look inside your frame to know what type
of package you are and the IP address of where you are
from and where you are going.
router: What type of packet are you? Or, what kind
of data do you contain?
HHTPlz: I'm requesting for a web page.
router: Great. Then you are a TCP packet. Here's
your frame. I've changed the origin MAC address to
my MAC address. You can put your frame back on now.
Have a great journey.

14. HTTPlz continues the
journey

15. AS12
gateway: You are at the
edge of NYU-NET. You
should not be here. You
should stay in AS12.
HTTPlz: AS12?
gateway: Yeah. Where do
you think you've been
all along?

16. HTTPlz: OMG. I've been
in AS12 all along.
gateway: duh. Don't get
lost again. Head that
way to your destination.
What is an Autonomous
System?
An autonomous system is a
collection of IP routing prefixes
governed by an administrator with
clearly defined routing policy to
the Internet. AS12 is the NYU-
Domain autonomous system. The
governing body is NYU.
A large network with needs to
connect many devices can become an
autonomous system with multiple IP
address spaces. It's like being
its own country with multiple area
codes.

17. ARRIVED
server:
Welcome.
I am the
host to all
data for
www.nyu.edu.
HTTPlz: Yes, I made it!
HTTPlz2: Yes, you made it!
HTTPlz: huh? who are you?
HTTPlz2: I'm your other half. I
hold the rest of the request for
the web page. We were too big at
birth, so we were split into two
and traveled our own journeys to
the server.

18. server: Let
me look this
up. Wait a
moment
please...HTTPlz & HTTPlz2:
We are one again!
Here is our
request

19. server: Here is
www.nyu.edu
NEW PACKETS
ARE BORN
We are going to
the laptop!

20. img: diving into a
computer
LET THE
NEW
JOURNEYS
BEGIN