Untagged ingress packets are destined to the native VLAN. An interface can be configured in one of two native modes - native untagged or native tagged.
A native untagged port accepts any untagged or tagged (with native VLAN ID) traffic on ingress.
Packets that egress on a native untagged port in the native VLAN will not have an 802.1Q header.
A native tagged port accepts only tagged traffic (with native VLAN ID) on ingress.
Any untagged packet ingress on a native tagged port is always dropped.
Packets that egress on a native tagged port in the native VLAN will always have an 802.1Q header.
(switch(config-if)#) Configure a VLAN as native:
vlan trunk native VLAN
(switch(config)#)
show vlan [VLAN]
(switch(config)#)
vlan 100
no shutdown
end
interface 1/1/1
no shutdown
no routing
vlan trunk native 100
exit
show vlan
Example output:
--------------------------------------------------------------------------------------
VLAN Name Status Reason Type Interfaces
--------------------------------------------------------------------------------------
1 DEFAULT_VLAN_1 down no_member_port default
100 VLAN100 up ok static 1/1/1