Open the lab

[ YOUR LAB FILE ]

Download the starting topology, then work through the lesson in SwitchLab.

Download SwitchLab Lab (.swlab)

  1. Save the .swlab file without renaming its extension.
  2. Open SwitchLab. Import and export controls currently require a desktop-width window. On a smaller screen, Tools → Fit brings the topology into view.
  3. Select Import Sandbox (folder icon), choose the downloaded file, and confirm the device and cable counts below.
  4. Select a device, then choose Open device on desktop or its name in the bottom bar on smaller screens. Select CLI for switches/routers or Desktop → Terminal for PCs. Enter enable only when the prompt ends in >.
  5. Follow this page beside the simulator. Use a free account to export your work. Reimport the original download to restart; export any work you want to keep first.

Prerequisites

  • Complete the VLAN and trunking progression.
  • Understand that redundant Layer 2 paths need loop prevention.

Follow the CCNA study path · Browse all SwitchLab labs

Topology

Design a Redundant Rapid-PVST Campus: starting network imported into the SwitchLab sandbox.
Starting topology captured in SwitchLab. Select the image to view it at full size.

7 devices · 7 links

Scenario

A small campus carries Users and Staff across a redundant triangle. Assign each VLAN to its preferred distribution root, keep a backup preference, and prove both departments survive a controlled link removal.

Objectives

  • Determine the root from operational spanning-tree output.
  • Verify explicit bridge priorities and converged host forwarding.

CCNA blueprint

200-301 v1.1 objectives — this lab covers the following specific skills, not every subtopic in the domain.

  • 2.5 — Interpret Rapid PVST+ root election, port roles and steady-state redundancy.

Starting information

  • VLAN 10 priorities: SW1=0, SW2=4096, SW3=32768. VLAN 20 priorities: SW2=0, SW1=4096, SW3=32768.
  • PC1/PC2 use VLAN 10; PC3/PC4 use VLAN 20 on g0/2 of SW2/SW3. All trunks carry both VLANs.
  • Use rapid-pvst mode already configured. This exercise proves steady-state roles and reachability, not real-time convergence speed.
HostIPv4 addressMaskGateway
PC1192.168.10.10255.255.255.0None
PC2192.168.10.20255.255.255.0None
PC3192.168.20.30255.255.255.0None
PC4192.168.20.40255.255.255.0None
Device / portDevice / port
SW1 / g0/7SW2 / g0/7
SW1 / g0/8SW3 / g0/8
SW2 / g0/8SW3 / g0/7
PC1 / eth0SW2 / g0/1
PC2 / eth0SW3 / g0/1
PC3 / eth0SW2 / g0/2
PC4 / eth0SW3 / g0/2

Tasks

  1. Audit both VLAN instances and write down the required primary and backup bridge for each.
  2. Apply the approved per-VLAN priorities while preserving trunks and access ports.
  3. Verify both roots and each department’s traffic. Explain why one physical switch can be root for one VLAN and not another.
  4. Shut g0/7 on both SW1 and SW2 to model that link unavailable. Inspect both spanning trees and test both departments. Restore both interfaces, verify again, then save/export.

Useful commands

show spanning-tree vlan 10
show running-config
show spanning-tree vlan 20
copy running-config startup-config

Progressive hints

Hint 1

Check the bridge priority before using MAC addresses to break an election tie.

Hint 2

A working ping proves delivery but does not tell you whether the intended switch is the root.

Hint 3

Use show spanning-tree vlan 10 on each switch; set only the priorities specified in the approved plan.

Verification

  • The intended root reports This bridge is the root for its assigned VLAN.
  • Configured bridge priorities match the approved primary and backup design.
  • Both directions of each department’s traffic succeed after the final restoration.

Solution / walkthrough

Show Solution

Use enable only from a > prompt; if already at #, begin with configure terminal.

SW1

Set a distinct primary and backup preference for each VLAN; preserve rapid-PVST and the existing trunk carriage.

enable
configure terminal
spanning-tree vlan 10 priority 0
spanning-tree vlan 20 priority 4096
end
copy running-config startup-config

SW2

Set a distinct primary and backup preference for each VLAN; preserve rapid-PVST and the existing trunk carriage.

enable
configure terminal
spanning-tree vlan 10 priority 4096
spanning-tree vlan 20 priority 0
end
copy running-config startup-config

SW3

Set a distinct primary and backup preference for each VLAN; preserve rapid-PVST and the existing trunk carriage.

enable
configure terminal
spanning-tree vlan 10 priority 32768
spanning-tree vlan 20 priority 32768
end
copy running-config startup-config

Run every verification check above after the changes. A saved configuration alone does not prove packet delivery.

Previous lab

Repair an Unintended STP Root Election

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