Day 6: The Internet as a Network of Networks

Learning Objectives

• CSN-1.E: For fault-tolerant systems like the Internet: a. Describe the benefits of fault tolerance. b. Explain how a given system is fault-tolerant. c. Identify vulnerabilities to failure in a system.

Essential Questions

• How is the Internet structured as a network of networks?
• How does information travel across the global Internet?
• How is the Internet governed and standardized?

Materials Needed

• Presentation slides on Internet structure
• Large world map (physical or digital)
• String or yarn for mapping connections
• Internet route mapping tools (e.g., traceroute)
• Exit ticket templates

Vocabulary

• Internet
• Autonomous system
• ISP (Internet Service Provider)
• Backbone
• Peering
• IXP (Internet Exchange Point)
• BGP (Border Gateway Protocol)
• ICANN
• IETF
• Internet governance

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review parallel and distributed computing from previous lesson
   • Connect to today's focus on the Internet as the world's largest distributed system

2. Warm-up Activity (5 minutes)

   • Ask students: "When you access a website hosted in another country, how does your data get there?"
   • Have students sketch or describe their understanding of the Internet's structure
   • Create a class list of student ideas about Internet structure
   • Introduce the concept of the Internet as a "network of networks"

Main Activities (32 minutes)

3. Lecture: Internet Structure and Autonomous Systems (12 minutes)

   • Define the Internet as a global network of interconnected computer networks
   • Explain key components of Internet structure:
     • Autonomous systems: Networks under single administrative control
     • Internet Service Providers (ISPs): Tier 1, 2, and 3
     • Internet backbones: High-capacity data routes
     • Internet Exchange Points (IXPs): Where networks connect
     • Edge networks: Where end users connect
   • Discuss Internet governance and standards:
     • ICANN: Domain names and IP addresses
     • IETF: Technical standards and protocols
     • W3C: Web standards
     • No central authority controls the entire Internet
   • Explain how the Internet's distributed structure provides resilience
   • Discuss how the Internet has evolved over time

4. Exploration: How Data Travels Across the Internet (10 minutes)

   • Demonstrate tools that show how data travels across the Internet (e.g., traceroute)
   • Show the path data takes to reach various websites
   • Identify the different networks (autonomous systems) data passes through
   • Discuss how routing decisions are made between networks
   • Explain how Border Gateway Protocol (BGP) enables inter-network routing
   • Show how the path might change over time or for different destinations

5. Activity: Mapping a Route Across Multiple Networks (10 minutes)

   • Divide class into groups of 3-4 students
   • Provide each group with a world map and string/yarn
   • Assign each group a scenario with source and destination locations
   • Groups map potential routes data might take across the Internet
   • Groups should identify:
     • Local networks at source and destination
     • ISPs that might be involved
     • Internet exchange points data might pass through
     • Undersea cables or satellite links for international connections
   • Groups share their maps and explain their routing decisions

Closing (10 minutes)

6. Discussion: Internet Governance and Standards (5 minutes)

   • Lead a discussion on how the Internet is governed
   • Explain that no single entity controls the entire Internet
   • Discuss the role of standards organizations
   • Explain how open standards enable interoperability
   • Address any misconceptions about Internet control

7. Exit Ticket: Internet Structure Visualization (5 minutes)

   • Students create a visual representation of how the Internet connects networks globally
   • Visualization should include:
     • Different types of networks
     • Connection points
     • The path data might take between two points
   • Collect visualizations before students leave

Assessment

• Formative: Quality of route mapping activity
• Exit Ticket: Accuracy and completeness of Internet structure visualization

Differentiation

For Advanced Students

• Ask them to research and include more technical details about routing protocols
• Have them explore how content delivery networks optimize data delivery
• Challenge them to consider how IPv6 affects Internet structure

For Struggling Students

• Provide a partially completed map for the routing activity
• Focus on the most essential Internet structure concepts
• Use more visual aids and concrete examples

Homework/Extension

• Research the physical infrastructure of the Internet (undersea cables, satellites, etc.)
• Use traceroute to map paths to different websites and analyze the results
• Create an infographic explaining how the Internet connects globally

Teacher Notes

• Use analogies to help students understand Internet structure (e.g., postal system, highway system)
• Be prepared to address questions about specific Internet technologies
• Make connections to students' everyday experiences with the Internet
• Consider showing videos of Internet infrastructure (data centers, cable laying, etc.)
• Emphasize that understanding Internet structure helps explain both its resilience and vulnerabilities