請問設定switch的trunk有無switchport trunk encapsulation dot1q的差別

假設要在fa0/1安裝vlan99的trunk
請問有無多switchport trunk encapsulation dot1q
除了native
這一行文字的差別是什麼
----------------指令1號--------------------
Switch>en
switchx#confgure terminal
switchx(congog)#interface fa0/1
switchx#(confg-if)#switchport mode trunk
switchx#(confg-if)#switchport trunk native vlan 99
----------------指令2號--------------------
Switch>en
switchx#confgure terminal
switchx(congog)#interface fa0/1
switchx#(confg-if)#witchport trunk encapsulation dot1q
switchx#(confg-if)#switchport mode trunk
switchx#(confg-if)#switchport trunk native vlan 99