Hi Christian,
in this case you have to configure a trunk port with a native vlan.
eg.
conf t
interface gig 1/1
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk native vlan 99
switchport trunk allowed vlan 100-105
Keep in mind: CIsco does not support Authentication (MAC or 802.1X) on a trunk port!
Best Regards
Michael