Problem IEEE 802.1q Sub-Interface Misconfiguration

Verify the subinterface status using the show ip interface brief command

Router-on-a-stick configuration problems are usually related to subinterface misconfigurations

Verify which VLANs each of the subinterfaces is on using the show interfaces command

The command output can be reduced using IOS command filters

In this example, use the include keyword to identify that only lines containing the letters “Gig” or “802.1Q”