One root per VLAN
The switches carry VLAN 10 (Sales) and VLAN 20 (HR) on trunks. Share the load:
- Rapid PVST+ on every switch.
- SW1: root for VLAN 10, backup root for VLAN 20.
- SW2: root for VLAN 20, backup root for VLAN 10.
Then check that each VLAN blocks a different link.
How it works: this is VulnTech NetLab, a network simulator running in your browser. Click a device in the diagram to open its console and type commands, just like on real equipment (? shows help, Tab finishes a word). Click a cable to inspect it. Tasks tick themselves off as you complete them; questions are answered in the box under each task. Your work is kept if you reload; Reset starts the network over.
Solution explanation
PVST+ builds one tree per VLAN, so each VLAN can have its own root. In VLAN 10 SW3 reaches SW1 directly on Gi0/1 and blocks Gi0/2 (towards SW2); in VLAN 20 it's the other way round. Both of SW3's uplinks now carry traffic, one VLAN each, and each is the backup path for the other VLAN.
Show solution
[SW1]
enable
configure terminal
spanning-tree mode rapid-pvst
spanning-tree vlan 10 root primary
spanning-tree vlan 20 root secondary
end
[SW2]
enable
configure terminal
spanning-tree mode rapid-pvst
spanning-tree vlan 20 root primary
spanning-tree vlan 10 root secondary
end
[SW3]
enable
configure terminal
spanning-tree mode rapid-pvst
end
show spanning-tree vlan 10 | begin Interface
show spanning-tree vlan 20 | begin Interface