U1Ch2L10_Routers and Redundancy

Purpose: Students will learn how internet traffic is managed.
Vocabulary: Routers, Network Redundancy, DNS, IP Address

Video: The Internet – IP Addresses and DNS
An explanation on how computers/servers are able to find each other and connect.
https://www.youtube.com/watch?v=5o8CwafCxnU
(Show the students how to connect from the class laptop to the class printer using the IP address and DNS protocols.)

Journal: Tracking a Postal Package.

1. At the end of class yesterday, we saw that the Internet uses the Internet Protocol and IP Addresses to communicate across the shared Internet. How is this system similar to how we send letters in the mail? How is it different?
2. Select a friend or relative that lives outside of the Bay Area, hopefully somewhere else in the US.
   Pretend you would like to send them a package. Right now in your journal, address the package as though you were going to mail it to your friend – if you don’t know the exact address, that ok, make it up.
   Starting with you leaving your house, write in your journal each time the package would change hands in order to reach its destination. Please feel free to make educated guesses as to how you think the package gets there. When you are done, please count the number of times a person, post office, computer, must make a decision about where to send the letter next.

State: In a network of computers, certain computers called “routers” do the same thing, directing messages towards the target computer based on the IP addresses included in the message. (Share with class)
IP Address: 32 Bits – 4 Billion Addresses.

Activity: New Version of the Internet Simulator – Routers And Redundancy
Go to the Internet Simulator at Code Studio
Choose a Router:
Add a router if you need more space. Then join a router with a few of the people sitting closest to you. Ideally, you’ll have 3-4 classmates with you on your router.

• Send a quick test message:
  • Send a simple “hello” to a friend who is connected to the same router.
• Find friend’s (small) IP address
  • Send a message to that address
  • Friend should send a response
• Continue to communicate.
  • What is your favorite food?
  • What is your favorite type of animal?
  • What is your favorite color?
  • Note: Be sure to also respond to questions you get from people on other routers!

Journal: Answer These Questions…
Read The Network Traffic! (Go To: Router Tab, then Log Browser button.) As a class, open the router logs and view the messages across all router logs. There should now be examples of messages appearing multiple times. Ask students to find one of their own messages and see how many times it appears. Our messages are being sent from router to router, bouncing between different routers in the network. Not all messages take the same path to get to their destination - in fact, even when sending multiple messages to the same person, messages may take different paths.

• How many total messages passed over your router?
• About what percent of those messages did you actually receive?
• Did all the messages get through? Why might a message have been “Dropped”?
• Can you trace a full conversation between two of your classmates? What types of things are people talking about?

Find A Classmate on a Different Router – communicate with them.

• Send three separate messages with your top three favorite movies or TV shows.
  • How many total messages passed over this new router?
  • Can you trace the full conversation between two of your classmates? What did they say?
  • Is there anything different about the way messages are being sent this time? Why might that be the case?
  • Send multiple messages to the same person on a different router. Do your messages always take the same path? What is this simulating?

Journal

• Can you know in advance the path a message will take between you and another computer on the Internet? Explain.
• An ISP just purchased all the routers in your area. What types of things is this ISP capable of doing? Are you comfortable with this arrangement?

• DNS: Allows us to identify a webpage by its name –eg. “rlsbluedevils.org.” -> this is the Domain Name.
• Domain names are easy for humans to understand – IP Addresses are easy for computers to understand.