VLAN (802.1q)ΒΆ

IEEE 802.1q, often referred to as Dot1q, is the networking standard that supports virtual LANs (VLANs) on an IEEE 802.3 Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames. The standard also contains provisions for a quality-of-service prioritization scheme commonly known as IEEE 802.1p and defines the Generic Attribute Registration Protocol.

Portions of the network which are VLAN-aware (i.e., IEEE 802.1q conformant) can include VLAN tags. When a frame enters the VLAN-aware portion of the network, a tag is added to represent the VLAN membership. Each frame must be distinguishable as being within exactly one VLAN. A frame in the VLAN-aware portion of the network that does not contain a VLAN tag is assumed to be flowing on the native VLAN.

The standard was developed by IEEE 802.1, a working group of the IEEE 802 standards committee, and continues to be actively revised. One of the notable revisions is 802.1Q-2014 which incorporated IEEE 802.1aq (Shortest Path Bridging) and much of the IEEE 802.1d standard.

802.1a VLAN interfaces are represented as virtual sub-interfaces in VyOS. The term used for this is vif. Configuration of a tagged sub-interface is accomplished using the configuration command: set interfaces ethernet <name> vif <vlan-id>

To assign a vif 100 using the VLAN 100 tag to physical interface eth1 use:

set interfaces ethernet eth1 vif 100 description 'VLAN 100'
set interfaces ethernet eth1 vif 100 address ''
set interfaces ethernet eth1 vif 100 address '2001:db8:100::1/64'

Resulting in:

ethernet eth1 {
    address 2001:db8:100::1/64
    description INSIDE
    duplex auto
    hw-id 00:53:29:44:3b:19
    smp_affinity auto
    speed auto
    vif 100 {
        description "VLAN 100"

VLAN interfaces are shown as <name>.<vlan-id>, e.g. eth1.100:

vyos@vyos:~$ show interfaces
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface        IP Address                        S/L  Description
---------        ----------                        ---  -----------
eth0                     u/u  OUTSIDE
eth1                       u/u  INSIDE
eth1.100                  u/u  VLAN 100
lo                            u/u