I have two Fortigate 300C devices in two buildings. The connection is a layer 3 connection with static routes, as shown in the uploaded picture. The connection between the two Fortigates is configured on port 2. Also on Port 2 there is a tunnel interface with an IP address. The routing configuration between the Fortigates is static routing. On port 1 on both Fortigates is the connection to the local network of both buildings (connection to the main switches of the buildings).
Now I want to transport a second network from the Fortigate 1 over Port 2 to the Fortigate 2 device. This second network is connected on port 3 on the device Fortigate 1. The port on the Switch pointing to the Fortigate 1 is tagged, with one VLAN (VLAN ID 20). I want to transport this VLAN 20 tagged from port 3 (Fortigate 1) over the Port 2 to the other device Fortigate 2 and connect a switch on Port 3 on Fortigate 2. This switch will add this tagged VLAN 20 on his uplink port and then the other Ports will be untagged.
How can I configure the Fortigates, that the Layer 2 network will be transported over the Layer 3 network? I've tried to create a vlan subinterface on port 2 and then created a software switch, combing the vlan and the port 3, but it sadly didn't work.
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.