Chapter 8 Hardware Acceleration : NP4 Acceleration : NP4 traffic shaping offloading
  
NP4 traffic shaping offloading
Accelerated Traffic shaping is supported with the following limitations.
NP4 processors support policy-based traffic shaping. However, fast path traffic and traffic handled by the FortiGate CPU (slow path) are controlled separately, which means the policy setting on fast path does not consider the traffic on the slow path.
The port based traffic policing as defined by the inbandwidth and outbandwidth CLI commands is not supported.
DSCP configurations are supported.
4QoS in general is not supported.
You can also use the traffic shaping features of the FortiGate unit’s main processing resources by disabling the NP4 acceleration. See “Disabling CP offloading”.