First of all, you must configure all 3 VLANs on all Switches. After that you can deploy the trunking ports configuration:<br/> Switch3: int fa0/5 <br/> Switchport mode trunk<br/> Switchport allowed vlan 1-3<br/> <br/> Switch2: int fa0/4 <br/> Switchport mode trunk<br/> Switchport allowed vlan 1-3<br/> Switch2: int fa0/1 <br/> Switchport mode trunk<br/> Switchport allowed vlan 1-3<br/> Switch1: int fa0/2 <br/> Switchport mode trunk<br/> Switchport allowed vlan 1-3<br/> I suppose that the Router R2 work like router on a stick ?<br/> Switch1: int fa0/3 <br/> Switchport mode trunk<br/> Switchport allowed vlan 1-3<br/> Cisco 2960 supports only IEEE 802.1Q trunking methods for sending VLAN traffic over Ethernet ports