Bundle the uplinks
SW1 and SW2 are joined by two gigabit links, but spanning tree blocks one of them. Bundle Gi0/1 and Gi0/2 on both switches into Port-channel 1 using LACP (SW1 actively negotiating, SW2 only answering), and make the port channel a trunk on both sides.
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
LACP needs at least one active side; active + passive bundles. Configuring the trunk on the port-channel interface applies it to both members, so they stay identical. Spanning tree now sees one link, Po1, and nothing is blocked.
Show solution
[SW1]
enable
configure terminal
interface range g0/1 - 2
channel-group 1 mode active
exit
interface port-channel 1
switchport mode trunk
end
[SW2]
enable
configure terminal
interface range g0/1 - 2
channel-group 1 mode passive
exit
interface port-channel 1
switchport mode trunk
end
show etherchannel summary