Router-on-a-Stick Fundamentals: Two VLANs, One Trunk

Bundle lab · $29.99

Configure inter-VLAN routing using router-on-a-stick with one router, one Layer-2 switch, and two hosts. Build VLAN 10 and VLAN 20, trunk the router uplink, create subinterfaces for each VLAN, and verify that hosts can now reach each other across VLANs.

Learning objectives

• Translate a two-VLAN addressing plan into router-on-a-stick subinterfaces
• Configure an 802.1Q trunk between a router and a Layer-2 switch
• Create VLANs on a Layer-2 switch and assign access ports correctly
• Verify inter-VLAN reachability from end hosts and with IOS show commands
• Recognize and correct trunk allow-list and access-port misconfiguration issues

Troubleshooting focus

• Detect a missing VLAN gateway (absent router subinterface)
• Identify a trunk that is not in 802.1Q mode or is pruned to the wrong allow-list
• Spot a host connected to the wrong access VLAN
• Confirm that the router physical interface carries no IP address and is up