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.
$