Chapter 17 Traffic Shaping for FortiOS 5.0 : Traffic shaping methods : Shared policy shaping : VLAN, VDOM and virtual interfaces
  
VLAN, VDOM and virtual interfaces
Policy-based traffic shaping does not use queues directly. It shapes the traffic and if the packet is allowed by the security policy, then a priority is assigned. That priority controls what queue the packet will be put in upon egress. VLANs, VDOMs, aggregate ports and other virtual devices do not have queues and as such, traffic is sent directly to the underlying physical device where it is queued and affected by the physical ports. This is also the case with IPsec connections.