The vlan node type multiplexes frames tagged according to the IEEE 802.1Q standard between different hooks.
Each node has two special hooks, downstream and nomatch, and an arbitrary number of "vlan" hooks, each associated with a particular VLAN tag.
An ETHERTYPE_VLAN frame received on the downstream hook with a tag that the node has been configured to filter is sent out the corresponding "vlan" hook. If it does not match any of the configured tags, or is not of a type ETHERTYPE_VLAN, it is sent out the nomatch hook. If the nomatch hook is not connected, the packet is dropped.
An Ethernet frame received on the nomatch hook is passed unmodified to the downstream hook.
An Ethernet frame received on any of the "vlan" hooks is tagged accordingly and sent out the downstream hook.
This node type supports the following hooks: