U2Ch1L5_ Packets

Purpose: Students will see that all information on the internet is broken into smaller chunks called packets and reassembled at the destination.
Vocabulary: TCP, UDP.

Journal: The school library is moving all its books to brand new facility on the other side of the campus. They have hired you to remove the books.

• Scenario #1:  You and your partner have one day to remove all the books and place them in storage. Develop a plan.
• Scenario #2: You and your partner have several days to remove all the books and then  check to make sure every book makes it to the new facility and place them on the same shelf they were on prior to the move. Develop a plan.

Activity: Log On to the Internet Simulator (U2Ch1L5_Packets)  

Lobby_Joining a Router:

• Join a Router different than your partner: “Add Router” / “Join”
• When you are on different routers, you will have to tell your classmates your IP number.

Send Message 1: Practice Round: 

• Enter the IP address of your partner and ask them a question (Favorite Food, Movie, etc.). o 
  • What Happened!! 
• Teacher: On the front screen (Promethean), View the following: Router tab / Log Browser / Show All Traffic (or by student/router). 
  • Students will notice that the Internet Simulator will cut the student’s message off at 8 letters and won’t send any additional letters or words beyond those first 8!
    • Solution: Break the message into smaller packets: “Add Packet!” – none longer than 8 bits. 
  • Also notice that the packets will arrive not in the correct order.

Send Message 2: Create Protocol

• Partners should write a Protocol to make transmission of the messages more efficient.
• Partners, send a message to each other and then reply to the message.
• Discuss & Refine Your Protocols.
• Since the Packets will most likely arrive out of order, what can you do to refine the protocol so that you will be able to at least read them in the intended order?

Send Teacher’s Message 3: Competition!

• The Teacher will hand a Partner #1 a post it with a question. Partner #1 will transmit it to Partner #2. Partner #2 will determine what the question is by using their protocol and reply with the answer.
• Partner 1 will receive the answer and must write it down.

Journal: We just experienced how frustrating it is to chop messages/files into smaller packets when sending them across the internet. Why is this such a valuable process for the success of the internet though? (pipes/rocks/sand)

Video: The Internet: Packets, Routing and Reliability.

Teacher Remark: Two protocols used to send data as packets are UDP and TCP. The User Datagram Protocol (UDP) simply sends all the packets. If some arrive out of order or are entirely missing there's no system to fix the errors. 

• In instances like live-streaming television or online gaming where speed is most important, UDP will be used since it is faster and there's less benefit to correcting errors. 

The Transmission Control Protocol (TCP) numbers packets before sending them so that the receiver can correctly reorder the packets and request missing packets be resent. 

• TCP takes longer than UDP because of the error-checking done to guarantee every packet was received. TCP is used to send information like emails, images, websites, and more where saving fractions of a second is less important than accuracy.