Virtual LAN (VLAN) Support
Overview
Virtual LAN (VLAN) is a partitioned and isolated computer network at the data link layer (OSI layer 2). For ethernet network this refers to IEEE 802.1Q
In Zephyr, each individual VLAN is modeled as a virtual network interface. This means that there is an ethernet network interface that corresponds to a real physical ethernet port in the system. A virtual network interface is created for each VLAN, and this virtual network interface connects to the real network interface. This is similar to how Linux implements VLANs. The eth0 is the real network interface and vlan0 is a virtual network interface that is run on top of eth0.
VLAN support must be enabled at compile time by setting option
CONFIG_NET_VLAN and CONFIG_NET_VLAN_COUNT to reflect how
many network interfaces there will be in the system. For example, if there is
one network interface without VLAN support, and two with VLAN support, the
CONFIG_NET_VLAN_COUNT option should be set to 3.
Even if VLAN is enabled in a prj.conf file, the VLAN needs to be
activated at runtime by the application. The VLAN API provides a
net_eth_vlan_enable() function to do that. The application needs
to give the network interface and desired VLAN tag as a parameter to that
function. The VLAN tagging for a given network interface can be disabled by a
net_eth_vlan_disable() function. The application needs to configure
the VLAN network interface itself, such as setting the IP address, etc.
See also the VLAN sample application for API usage example. The source code for that sample application can be found at samples/net/vlan.
The net-shell module contains net vlan add and net vlan del commands that can be used to enable or disable VLAN tags for a given network interface.
See the IEEE 802.1Q spec for more information about ethernet VLANs.