A packet's journey through NYU-NET

The Neverending

Story

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.

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.

LET THE JOURNEY BEGIN

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.

SERVER

where www.nyu.edu is hosted

LAPTOP

NYU-NET

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???

??????

???

???

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???

??????

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?

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?

SWITCHHTTPlz: 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.

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...

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.

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.

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.

HTTPlz continues the journey

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?

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.

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.

server: Let me look this up. Wait a moment

please...

HTTPlz & HTTPlz2: We are one again!Here is our request

server: Here is www.nyu.edu

NEW PACKETS ARE BORN

We are going to the laptop!

img: diving into a computer

LET THE NEW JOURNEYS BEGIN