===== Trunks =====
  * To configure a trunk between two switches:
    * Switch1(config)#** interface g1/0/20 **
    * Switch1(config-if)#** switchport trunk encapsulation dot1q **
    * Switch1(config-if)#** switchport mode trunk **
    * Switch1(config-if)#** switchport trunk allowed vlan 100,200 **
    * ---
    * Switch2(config)#** interface g1/0/20 **
    * Switch2(config-if)#** switchport trunk encapsulation dot1q **
    * Switch2(config-if)#** switchport mode trunk **
    * Switch2(config-if)#** switchport trunk allowed vlan 100,200 **

  * Optionally, you can change the native VLAN, which will VLAN will get tagged over the trunk link.
    * Switch(config-if)#** switchport trunk native vlan 99**