Chapter 17 Traffic Shaping for FortiOS 5.0 : Examples : Example setup for VoIP
  
Example setup for VoIP
In this example, there are three traffic shaping requirements for a network:
Voice over IP (VoIP) requires a guaranteed, high-priority for bandwidth for telephone communications.
FTP bursts must be contained so as not to consume any available bandwidth. As such this traffic needs to be throttled to a smaller amount.
A consistent bandwidth requirement is needed for all other email and web-based traffic.
To enable this requirement, you need to create three separate shapers and three security policies for each traffic type.
For this example, the actual values are not actual values, they are used for the simplicity of the example.
See also 
Creating the traffic shapers
Creating security policies
QoS using priority from security policies
QoS using priority from ToS or differentiated services