interface FastEthernet0.20

encapsulation dot1Q 20
no ip route-cache
bridge-group 1
no bridge-group 1 source-learning
bridge-group 1 spanning-disabled

! Supports shortened versions of config words, too inter gi0.10 encap dot1q 10 native inter gi0

banner login # Authenticate yourself! #

! Supports #, $ and % to delimit banners, and multiline banner motd $ Attention! We will be having scheduled system maintenance on this device. $