Alabourre.com

Sur Switch

configure terminal
  interface fa0/20
    description CONNECTION TO ROUTER-ON-A-STICK
    switchport trunk encapsulation dot1q
    switchport mode trunk

Sur Routeur

configure terminal
  interface fa0/0
    no ip address
    exit
  interface fa0/0.10
    description ROUTER INTERFACE FOR VOICE VLAN
    encapsulation dot1q 10
    ip address 172.16.1.1 255.255.255.0
    ip helper-address 172.16.2.5
    exit
  interface fa0/0.50
    description ROUTER INTERFACE FOR DATA VLAN
    encapsulation dot1q 50
    ip address 172.16.2.1 255.255.255.0