In some cases, packets in a multicast traffic stream with fragmented packets can be forwarded by the FortiGate in the wrong order. This can happen if different CPU cores are processing different packets from the same multicast stream. If you notice this problem, on some FortiGates with NP6 processors you can use the following command to configure the FortiGate to send all traffic received by an interface to the same CPU core.
config system npu
set cpu-core <core-number>
<interface-name> is the name of the interface to map to a CPU core. You can map any interface connected to an NP6 processor to a CPU core.
<core-number> is the number of the CPU core to map to the interface. Use
? to see the list of available CPU cores. You can map one CPU core to an interface. The default setting is
all, which maps the traffic to all CPU cores.