Confusion about VLANs

hi,

they work the same as in Cisco.

on the FortiGate you create a interface where you select the parent/physical interface and the vlan id to tag it ( subinterface ).

on the FortiSwitch you create the vlan and tag it on the port ( trunk interface ) - https://docs.fortinet.com/document/fortiswitch/6.4.6/administration-guide/146333/vlans-and-vlan-tagging#Configur

these 2 interfaces need to be directly connected between them and should work.

https://docs.fortinet.com/document/fortigate/7.0.0/ngfw-deployment/487675/lans-and-lan-segmentation 

On Fortinet it’s the same logic as Cisco, just split in two places, and that’s why it feels confusing at first.

- A VLAN on the FortiGate is like creating a sub-interface on a Cisco router (int g0/0.10 vlan 10).
- A VLAN on the FortiSwitch is like configuring the switchport VLANs on a Cisco switch (access or trunk with tags).

You connect the FortiGate port to the FortiSwitch uplink, tag the same VLAN IDs on both sides, and it works exactly like router-on-a-stick on Cisco.

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Configure-Inter-VLAN-Routing-on-the-FortiGate/ta-p/275524
https://pingmynetwork.com/network/ccna-200-301/intervlan-routing