Day 10: Scaling and Performance

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.
• CSN-2.B: Describe benefits and challenges of parallel and distributed computing.

Essential Questions

• How do networks and systems handle growth in users and data?
• What challenges arise when scaling networks?
• How do technologies like CDNs improve performance at scale?

Materials Needed

• Presentation slides on network scaling and performance
• Network performance testing tools
• Case study materials on scaling challenges
• Performance bottleneck scenario cards
• Exit ticket templates

Vocabulary

• Scalability
• Vertical scaling
• Horizontal scaling
• Load balancing
• Content Delivery Network (CDN)
• Caching
• Latency
• Bandwidth
• Throughput
• Quality of Service (QoS)

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review fault tolerance and redundancy from previous lesson
   • Connect to today's focus on handling growth and maintaining performance

2. Warm-up Activity (5 minutes)

   • Ask students: "What happens to a website when it suddenly becomes popular?"
   • Discuss challenges that arise with rapid growth in users or data
   • Create a class list of potential scaling issues
   • Introduce the concept of scalability

Main Activities (32 minutes)

3. Lecture: Network Scaling Challenges (12 minutes)

   • Define scalability as the capacity for a system to handle growth
   • Explain key scaling approaches:
     • Vertical scaling: Adding more resources to existing systems
     • Horizontal scaling: Adding more systems
     • Geographic distribution: Placing resources closer to users
   • Discuss common scaling challenges:
     • Increased load on servers
     • Network congestion
     • Database bottlenecks
     • Single points of failure under stress
     • Coordination overhead
   • Explain technologies that enable scaling:
     • Load balancers: Distributing traffic across servers
     • Content Delivery Networks: Caching content closer to users
     • Distributed databases: Spreading data across multiple systems
     • Cloud computing: Flexible resource allocation
   • Discuss performance metrics:
     • Latency: Time for data to travel
     • Bandwidth: Maximum data transfer rate
     • Throughput: Actual data transfer rate
     • Response time: Time to complete a request

4. Exploration: Content Delivery Networks (8 minutes)

   • Explain how CDNs work:
     • Distributed servers across geographic locations
     • Caching static content
     • Routing users to the closest server
     • Absorbing traffic spikes
   • Demonstrate CDN benefits with examples:
     • Before/after page load times
     • Traffic handling during peak events
     • Protection against certain attacks
   • Show how CDNs use DNS and routing to direct users
   • Discuss how major websites and services use CDNs

5. Activity: Analyzing Performance Bottlenecks (12 minutes)

   • Divide class into small groups
   • Provide each group with a case study of a scaling challenge
   • Groups analyze the scenario to:
     • Identify performance bottlenecks
     • Determine root causes
     • Propose scaling solutions
     • Consider trade-offs of different approaches
   • Groups create a brief presentation of their analysis
   • Share and discuss different approaches to scaling

Closing (10 minutes)

6. Discussion: Future Internet Challenges (5 minutes)

   • Lead a discussion on emerging challenges for Internet scaling:
     • Growing number of connected devices (IoT)
     • Increasing video and streaming traffic
     • Cloud gaming and virtual reality
     • Global connectivity in developing regions
   • Discuss potential solutions and technologies
   • Address any misconceptions about network capacity

7. Exit Ticket: Performance Improvement (5 minutes)

   • Present students with a network performance scenario
   • Students propose solutions to improve performance
   • Students explain the benefits of their approach
   • Students identify potential trade-offs or new challenges
   • Collect responses before students leave

Assessment

• Formative: Quality of performance bottleneck analysis
• Exit Ticket: Appropriateness of performance improvement solutions

Differentiation

For Advanced Students

• Ask them to analyze more complex scaling scenarios
• Have them research and explain specific scaling technologies in detail
• Challenge them to consider economic factors in scaling decisions

For Struggling Students

• Provide more structured analysis templates
• Focus on the most essential scaling concepts
• Use more visual aids and concrete examples

Homework/Extension

• Research how a major website or service handles scaling
• Compare different CDN providers and their features
• Create a diagram showing how a system scales from small to large

Teacher Notes

• Use analogies to help students understand scaling (e.g., highway traffic, restaurant service)
• Be prepared to address questions about specific scaling technologies
• Make connections to students' experiences with slow websites or services
• Consider discussing real-world examples of scaling failures (e.g., website crashes during major events)
• Emphasize that understanding scaling helps with designing systems that can grow
• This concludes Week 2 of the unit