Service Manual
Typically, a Layer 3 physical interface processes only untagged or priority-tagged packets. Tagged packets that are received on Layer
3 physical interfaces are dropped. To enable the routing of tagged packets, the port that receives such tagged packets needs to be
congured as a switchport and must be bound to a VLAN as a tagged member port.
A lite subinterface is similar to a normal Layer 3 physical interface, except that additional provisioning is performed to set the VLAN
ID for encapsulation.
A physical interface or a Layer 3 Port channel interface can be congured as a lite subinterface. Once a lite subinterface is
congured, only tagged IP packets with encapsulation VLAN ID are processed and routed. All other data packets are discarded
except the Layer 2 and Layer 3 control frames. It is not required for a VLAN ID to be preserved (in the hardware or the OS
application) when a VLAN ID, used for encapsulation, is associated with a physical/Port-channel interface. Normal VLANs and VLAN
encapsulation can exist simultaneously and any non-unicast trac received on a normal VLAN is not ooded using lite subinterfaces
whose encapsulation VLAN ID matches with that of the normal VLAN ID.
You can use the encapsulation dot1q vlan-id command in INTERFACE mode to congure lite subinterfaces.
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