Routing and Switching

Active learning works for routing and switching because these concepts are abstract and spatial. When students manipulate virtual devices, build subnets, and compare address types, they turn theory into tangible experience. This hands-on approach clarifies how traffic moves through networks and reduces confusion between local and global forwarding decisions.

• 12th Grade
• Computer Science
• 3 activities
• 20 min–50 min

Learning Objectives

1. Analyze the decision-making process a router uses to forward a packet based on its routing table.
2. Compare and contrast the primary functions of network switches and routers in directing data traffic.
3. Design a simple network topology, illustrating how IP addresses and subnet masks facilitate communication.
4. Calculate appropriate subnet masks and network addresses for a given set of network requirements.
5. Evaluate the impact of a critical node failure on network traffic and explain potential rerouting strategies.

Simulation Game

⏱ 40 min·Whole Class

Simulation Game: Router Decision Tables

Give each student a routing table card listing two or three destination networks and which port leads to them. Students arrange themselves as nodes in a simple network drawn on the whiteboard. The teacher sends a message to a specific IP address, and the class routes the message hop by hop, each router consulting their card to decide where to forward it next.

Prepare & details

What happens when a critical node in a global network fails and how is traffic rerouted?

Facilitation Tip: For the Router Decision Tables activity, assign each group a different subnet mask so their tables look distinct, making it easier to spot patterns during the debrief.

Setup: Flexible space for group stations

Materials: Role cards with goals/resources, Game currency or tokens, Round tracker

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Inquiry Circle

⏱ 50 min·Small Groups

Inquiry Circle: Subnetting Challenge

Groups receive a scenario: a school district needs to divide one Class C network block into subnets for five departments of different sizes. They calculate subnet masks, determine valid host ranges, and verify their work does not leave address conflicts. Groups present their design and explain the trade-offs they made between subnet size and number.

Prepare & details

Differentiate between the functions of routers and switches in a network.

Facilitation Tip: In the Subnetting Challenge, provide colored cards or markers so students can visually separate subnets on their whiteboards before writing the final configuration.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Think-Pair-Share

⏱ 20 min·Pairs

Think-Pair-Share: IPv4 vs. IPv6

Present the fact that IPv4 supports about 4.3 billion addresses , a number that seemed impossibly large in the 1980s but became exhausted in the 2010s. Students individually brainstorm what caused the shortage, then pair up to compare ideas and share with the class. The discussion leads naturally into how IPv6's 128-bit addressing solves the problem.

Prepare & details

Design a simple network topology and explain how data would be routed between devices.

Facilitation Tip: During the IPv4 vs. IPv6 discussion, assign roles like 'IPv4 defender' or 'IPv6 advocate' to push students into defending their positions with evidence.

Setup: Standard classroom seating; students turn to a neighbor

Materials: Discussion prompt (projected or printed), Optional: recording sheet for pairs

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

Teaching This Topic

Teach routing and switching by starting with the physical building metaphor. Use analogies like mail rooms for switches and postal services for routers to ground abstract addressing in familiar systems. Avoid overwhelming students with binary math early. Instead, let them experience address calculation through guided steps before introducing formulas. Research shows that students grasp subnet masks better when they see how changing one octet directly alters host capacity.

What to Expect

By the end of these activities, students will confidently explain the difference between switches and routers using MAC and IP addressing. They will calculate subnets based on real-world host requirements and justify IPv4 vs. IPv6 decisions with technical reasoning. Look for accurate labeling on diagrams and precise calculations in their work.

Watch Out for These Misconceptions

Common Misconception

During Simulation: Router Decision Tables, watch for students who group all devices under one forwarding table, assuming routers and switches operate identically.

What to Teach Instead

Use the router decision tables to show that switches use MAC tables to forward frames within a single network, while routers consult IP tables to forward packets between different networks. Ask students to physically separate their tables into 'Local Delivery' and 'Remote Routing' sections.

Common Misconception

During Collaborative Investigation: Subnetting Challenge, watch for students who assume all subnets must be equal in size.

What to Teach Instead

Direct students to the unequal subnetting scenario in the challenge materials. Have them calculate host capacity for subnets sized 126 and 14 addresses and compare the subnet masks. Ask them to explain why the mask 255.255.255.128 allows 126 hosts but 255.255.255.240 only allows 14.

Assessment Ideas

Quick Check

After Simulation: Router Decision Tables, present students with a network diagram showing two switches connected to a router. Ask them to label which devices use MAC addresses, which use IP addresses, and to identify the router’s role in forwarding traffic between networks.

Discussion Prompt

During Collaborative Investigation: Subnetting Challenge, ask groups to share their unequal subnetting solutions. Then facilitate a class discussion on how subnet masks control host capacity, using their examples to correct the idea that subnets must be equal halves.

Exit Ticket

After Think-Pair-Share: IPv4 vs. IPv6, give students an exit ticket with two IP addresses, one IPv4 and one IPv6. Ask them to explain which protocol each address belongs to and one advantage of using IPv6 in modern networks.

Extensions & Scaffolding

• Challenge: Ask students to design a network for a school with 3 departments needing 200, 50, and 150 devices respectively, requiring them to subnet a /24 network without using 255.255.255.0.
• Scaffolding: Provide a partially completed subnet table with missing network or broadcast addresses for students to fill in before calculating their own.
• Deeper: Have students research how dynamic routing protocols like OSPF or BGP handle route selection during real-world failures and present their findings to the class.

Key Vocabulary

IP Address	A unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It identifies the host and its network.
Subnet Mask	A number that defines the range of IP addresses available within a network. It separates the network portion from the host portion of an IP address.
Router	A networking device that forwards data packets between computer networks. Routers perform traffic directing functions on the Internet.
Switch	A networking device that connects devices together on a computer network, using packet switching to receive, process, and forward data to the destination device.
Routing Table	A data table stored in a router or networked computer that lists the routes to particular network destinations or the addresses of neighboring routers.