A.Switch-3548(config-if)#switchport trunk encapsulation dotlq
Switch-3548(config-if)#switchport trunk allowed vlan 1,10,20,30
B.Switch-3548(config-if)#switchport mode trunk
Switch-3548(config-if)#switchport trunk encapsulation is1
Switch-3548(config-if)#switchport tnmk allowed vlan 1-30
C.Switch-3548(config-if)#switchport mode trunk
Switch-3548(config-if)#switchport trunk encapsulation negotiate
Switch-3548(config-if)#switchport trunk allowed vlan 1-30
D.Switch-3548(config-if)#switchport mode trunk
Switch-3548(config-if)#switchport trunk encapsulation dotlq
Switch-3548(config-if)#switchport trunk allowed vlan 1,10,20,30