18 Installing the SoftwareAssign Interfaces to a VLANOnly interfaces in Layer 2 mode can be assigned to a VLAN using the taggedand untagged commands. Use the switchport command to place an interface inLayer 2 mode.These Layer 2 interfaces can further be designated as tagged or untagged. Whenan interface is placed in Layer 2 mode by the switchport command, theinterface is automatically designated untagged and placed in the Default VLAN.To view which interfaces are tagged or untagged and to which VLAN theybelong, use the show vlan command. To view just the interfaces that are inLayer 2 mode, enter the show interfaces switchport command in the EXECPrivilege mode or EXEC mode.To tag frames leaving an interface in Layer 2 mode, you must assign thatinterface to a port-based VLAN to tag it with that VLAN ID. To tag interfaces,use these commands in the following sequence:Use the untagged command to move untagged interfaces from the DefaultVLAN to another VLAN:Step Task Command Syntax Command Mode1 Access theINTERFACE VLANmode of the VLAN towhich you want toassign the interface.interface vlan vlan-id CONFIGURATION2 Enable an interface toinclude the IEEE802.1Q tag header.tagged interface INTERFACEStep Task Command Syntax Command Mode1 Access theINTERFACE VLANmode of the VLAN towhich you want toassign the interface.interface vlan vlan-id CONFIGURATION