It’s possible to implement 802.1Q VLAN tagging with FreeBSD (as long as the hardware supports it). The documentation is rather sparse on this. All the intricate details are hidden in the man pages for vlan(4) and rc.conf(5).
Possible application for this are:
- A Router-On-A-STick – for inter-VLAN routing via a switch’s trunk port.
- Distribution of NTP to isolated subnets via a switch’s trunk port.